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Know about 3G Vs Wi-fi

sailjamehra — Thu, 08 Sep 2011 04:22:19 +0000

Know about 3G Vs Wi-fi

The two most important phenomena impacting telecommunications over the past decade have been explosive parallel growth of both the internet and mobile telephone services. The internet brought the benefits of data communications to the masses with email, the web, and ecommerce; while mobile service has enabled “follow-me anywhere/always on” telephony. The internet helped accelerate the trend from voice-centric to data-centric networking. Data already exceeds voice traffic and the data share continues to grow. Now these two worlds are converging. This convergence offers the benefits of new interactive multimedia services coupled to the flexibility and mobility of wireless. To realize the full potential of this convergence, however, we need broadband access connections.

Here we compare and contrast two technologies that are likely to play important roles: Third Generation mobile (“3G”) and Wireless Local Area Networks (“WLAN”) . The former represents a natural evolution and extension of the business models of existing mobile providers. In contrast, the WiFi approach would leverage the large installed base of WLAN infrastructure already in place. We use 3G and WiFi as shorthand for the broad classes of related technologies that have two quiet distinct industry origins and histories.

Speaking broadly, 3G offers a vertically -integrated , top -down , service – provider approach to delivering wireless internet access , while WiFi offers an end -user -centric , decentralized approach to service provisioning. We use these two technologies to focus our speculations on the potential tensions between these two alternative world views. The wireless future will include a mix of heterogenous wireless access technologies. Moreover, we expect that the two world views will converge such that vertically-integrated service providers will integrate WiFi or other WLAN technologies into their 3G or wire line infrastructure when this make sense. The multiplicity of potential wireless access technologies and /or business models provided some hope that we may be able to realize robust facilities – based competition for broadband local access services. If this occurs, it would help solve the “last mile” competition problem that has been deviled telecommunication policy.

SOME BACKGROUND ON WiFi AND 3G

3G:

3G is a technology for mobile service providers. Mobile services are provided by service providers that own and operate their own wireless networks and sell mobile services to and -users. Mobile service providers use licensed spectrum to provide wireless telephone coverage over some relatively large contiguous geographic service area. Today it may include the entire country. From a user’s perspective, the key feature of mobile service is that it offers ubiquitous and continuous coverage. To support the service, mobile operators maintain a network of interconnected and overlapping mobile base stations that hand-off customers as those customers move among adjacent cells. Each mobile base station may support user’s upto several kilometers away. The cell towers are connected to each other by a backhaul network that also provides interconnection to the wire line Public Switched Telecommunications Network (PSTN) and other services. The mobile system operator owns the end-to-end network from the base stations to the backhaul networks to the point of interconnection to the PSTN. Third

Generations (3G) mobile technologies will support higher bandwidth digital communications. To expand the range and capability of data services that can be supported by digital mobile systems, service providers will have to upgrade their networks to one of the 3G technologies which can support data rates of from 384Kbps up to 2Mbps.

WiFi

WiFi is the popular name for the wireless Ethernet 802.11b standard for WLANs . WiFi allows collections of PCs, terminals ,and other distributed computing devices to share resources and peripherals such as printers, access servers etc. One of the most popular LAN technologies was Ethernet.

HOW ARE WiFi AND 3G SAME

From the preceding discussion, it might appear that 3G and WiFi address completely different user needs in quiet distinct markets that do not overlap. While this was certainly more true about earlier generations of mobile services when compared with wired LANs or earlier versions of WLANs , it is increasingly not the case. The end- user does not care what technology is used to support his service. What matter is that both of these technologies are providing platforms for wireless access to the internet and other communication services.

Wifi

Wi-Fi ( /ˈ w aɪ f aɪ /) is a branded standard for wirelessly connecting electronic devices. A Wi-Fi device, such as a personal computer, video game console, smartphone, or digital audio player can connect to the Internet via a wireless network access point. An access point (or hotspot) has a range of about 20 meters (65 feet) indoors and a greater range outdoors. Multiple overlapping access points can cover large areas.

“Wi-Fi” is a trademark of the Wi-Fi Alliance and the brand name for products using the IEEE 802.11 family of standards. Wi-Fi is used by over 700 million people, there are over 4 million hotspots (places with Wi-Fi Internet connectivity) around the world, and about 800 million new Wi-Fi devices every year.^[^{citation needed}^] Wi-Fi products that complete the Wi-Fi Alliance interoperability certification testing successfully can use the Wi-Fi CERTIFIEDdesignation and trademark

Wi-Fi certification

See also: Wi-Fi Alliance.

The Alliance enforces its use to identify a range of connectivity technologies based on the IEEE 802.11 standards from the Institute of Electrical and Electronics Engineers including wireless local area network (WLAN) connections, device to device connectivity [such as Wi-Fi Peer to Peer AKA Wi-Fi Direct], Personal area network (PAN), local area network (LAN) and even some limited wide area network (WAN) connections. Derivative terms, such as Super Wi-Fi, coined by the U.S. Federal Communications Commission (FCC) to describe proposed networking in the UHF TV band in the US, may or may not be sanctioned by the alliance.

Not every Wi-Fi device is submitted for certification to the Wi-Fi Alliance. The lack of Wi-Fi certification does not necessarily imply a device is incompatible with Wi-Fi devices/protocols. If it is compliant or partly compatible, the Wi-Fi Alliance may not object to its description as a Wi-Fi device though technically only the CERTIFIED designation carries their approval.

Wi-Fi certified and compliant devices are installed in many personal computers, video game consoles, MP3 players, smartphones, printers, digital cameras, and laptop computers. Some of these devices can share their internet connection, becoming a hotspot or “virtual router”.^[1]

Wi-Fi technology builds on IEEE 802.11 standards. The IEEE develops and publishes some of these standards, but does not test equipment for compliance with them. The non-profit Wi-Fi Alliance formed in 1999 to fill this void — to establish and enforce standards for interoperability and backward compatibility, and to promote wireless local-area-network technology. As of 2010 the Wi-Fi Alliance consisted of more than 375 companies from around the world.^[2]^[3] Manufacturers with membership in the Wi-Fi Alliance, whose products pass the certification process, gain the right to mark those products with the Wi-Fi logo.

Specifically, the certification process requires conformance to the IEEE 802.11 radio standards, the WPA and WPA2 security standards, and the EAP authentication standard. Certification may optionally include tests of IEEE 802.11 draft standards, interaction with cellular-phone technology in converged devices, and features relating to security set-up, multimedia, and power-saving.^[4]

Most recently, a new security standard, Wi-Fi Protected Setup, allows embedded devices with limited graphical user interface to connect to the Internet with ease. Wi-Fi Protected Setup has 2 configurations: The Push Button configuration and the PIN configuration. These embedded devices are also called The Internet of Things and are low-power, battery-operated embedded systems. A number of Wi-Fi manufacturers design chips and modules for embedded Wi-Fi, such as GainSpan.^[5]

The name Wi-Fi

The term Wi-Fi suggests Wireless Fidelity, resembling the long-established audio-equipment classification term high fidelity (in use since the 1930s^[6]) or Hi-Fi(used since 1950^[6]). Even the Wi-Fi Alliance itself has often used the phrase Wireless Fidelity in its press releases^[7]^[8] and documents;^[9]^[10] the term also appears in a white paper on Wi-Fi from ITAA.^[11] However, based on Phil Belanger’s^{[note 1]} statement, the term Wi-Fi was never supposed to mean anything at all.^[12]^[13]

The term Wi-Fi, first used commercially in August 1999,^[14] was coined by a brand-consulting firm called Interbrand Corporation that the Alliance had hired to determine a name that was “a little catchier than ‘IEEE 802.11b Direct Sequence’”.^[12]^[13]^[15] Belanger also stated that Interbrand invented Wi-Fi as a play on words with Hi-Fi, and also created the Wi-Fi logo.

The Wi-Fi Alliance initially used an advertising slogan for Wi-Fi, “The Standard for Wireless Fidelity”,^[12] but later removed the phrase from their marketing. Despite this, some documents from the Alliance dated 2003 and 2004 still contain the term Wireless Fidelity.^[9]^[10] There was no official statement related to the dropping of the term.

The yin-yang Wi-Fi logo indicates the certification of a product for interoperability.^[9]

Non Wi-Fi technologies intended for fixed points such as Motorola Canopy are usually described as fixed wireless. Alternative wireless technologies include mobile phone standards such as 2G, 3G or4G.

]Uses

To connect to a WiFi LAN, a computer has to be equipped with a wireless network interface controller. The combination of computer and interface controller is called a station. All stations share a single radio frequency communication channel. Transmissions on this channel are received by all stations within range. The hardware provides no indication to the sender about whether the transmission was delivered and is therefore called a best-effort delivery mechanism. A carrier wave is used to transmit the data in packets, referred to as Ethernet frames. Each station is constantly tuned in on the channel, so each transmission is noticed. In order to determine whether the channel is free, the carrier wave can be sensed by the hardware; if not present the channel is free for transmission.

Internet access

A Wi-Fi enabled device such as a personal computer, video game console, smartphone or digital audio player can connect to the Internet when within range of a wireless network connected to the Internet. The coverage of one or more (interconnected) access points — called hotspots — can comprise an area as small as a few rooms or as large as many square miles. Coverage in the larger area may depend on a group of access points with overlapping coverage. Wi-Fi technology has been used in wireless mesh networks, for example, in London, UK.^[16]

In addition to private use in homes and offices, Wi-Fi can provide public access at Wi-Fi hotspots provided either free-of-charge or to subscribers to various commercial services. Organizations and businesses - such as those running airports, hotels and restaurants – often provide free-use hotspots to attract or assist clients. Enthusiasts or authorities who wish to provide services or even to promote business in selected areas sometimes provide free Wi-Fi access. As of 2008 more than 300 metropolitan-wide Wi-Fi (Muni-Fi) projects had started.^[17] As of 2010 the Czech Republic had 1150 Wi-Fi based wireless Internet service providers.^[18]^[19]

Routers that incorporate a digital subscriber line modem or a cable modem and a Wi-Fi access point, often set up in homes and other premises, can provide Internet access and internetworking to all devices connected (wirelessly or by cable) to them. With the emergence of MiFi and WiBro (a portable Wi-Fi router) people can easily create their own Wi-Fi hotspots that connect to Internet via cellular networks. Now iPhone, Android, Bada and Symbian phones can create wireless connections.^[20]

One can also connect Wi-Fi devices in ad-hoc mode for client-to-client connections without a router. Wi-Fi also connects places that would traditionally not have network access, for example kitchens and garden sheds.

City-wide Wi-Fi

In the early 2000s, many cities around the world announced plans for city-wide Wi-Fi networks. This proved to be much more difficult than their promoters initially envisioned with the result that most of these projects were either canceled or placed on indefinite hold. A few were successful, for example in 2005,Sunnyvale, California became the first city in the United States to offer city-wide free Wi-Fi,^[21] and Minneapolis has generated $1.2 million profit annually fortheir provider.^[22]

In May, 2010, London, UK Mayor Boris Johnson pledged London-wide Wi-Fi by 2012.^[23] Both the City of London, UK^[24] and Islington^[25] already have extensive outdoor Wi-Fi coverage.

In 2010 Mysore became India’s first Wi-fi enabled city and second in the world after Jerusalem. A company called WiFiyNet has setup hotspots in Mysore covering the complete city and a few villages nearby.^[^{citation needed}^]

Campus-wide Wi-Fi

Carnegie Mellon University built the first wireless Internet network using similar technology at their Pittsburgh campus in 1994, before Wi-Fi branding originated.^[26] Many traditional college campuses provide at least partial wireless Wi-Fi Internet coverage.

Drexel University in Philadelphia became the United States’ first major university to offer completely wireless Internet access across the entire campus in 2000.^[27]

Direct computer-to-computer communications

Wi-Fi also allows communications directly from one computer to another without the involvement of an access point. This is called the ad hoc mode of Wi-Fi transmission. This wireless ad hoc networkmode has proven popular with multiplayer handheld game consoles, such as the Nintendo DS, digital cameras, and other consumer electronics devices.

Disadvantage of this method is that vendors must not implement speeds greater that 11 Mbps(802.11b)^[28] and only WEP encryption is available, not WPA(2).^[^{citation needed}^]

Similarly, the Wi-Fi Alliance promotes a specification called Wi-Fi Direct for file transfers and media sharing through a new discovery- and security-methodology.^[29] Wi-Fi Direct launched in October 2010.^[30]

Future directions

As of 2010 Wi-Fi technology has spread widely within business and industrial sites. In business environments, just like other environments, increasing the number of Wi-Fi access points provides network redundancy, support for fast roaming and increased overall network-capacity by using more channels or by defining smaller cells. Wi-Fi enables wireless voice-applications (VoWLAN or WVOIP). Over the years, Wi-Fi implementations have moved toward “thin” access points, with more of the network intelligence housed in a centralized network appliance, relegating individual access points to the role of “dumb” transceivers. Outdoor applications may use mesh topologies.

Advantages and problems

Advantages

Wi-Fi allows cheaper deployment of local area networks (LANs). Also spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.

Manufacturers are building wireless network adapters into most laptops. The price of chipsets for Wi-Fi continues to drop, making it an economical networking option included in even more devices.^[^{citation needed}^]

Different competitive brands of access points and client network-interfaces can inter-operate at a basic level of service. Products designated as “Wi-Fi Certified” by the Wi-Fi Alliance are backwards compatible. Unlike mobile phones, any standard Wi-Fi device will work anywhere in the world.

Wi-Fi operates in more than 220,000 public hotspots and in tens of millions of homes and corporate and university campuses worldwide.^[31] The current version of Wi-Fi Protected Access encryption (WPA2) as of 2010 is widely considered secure, provided users employ a strong passphrase. New protocols forquality-of-service (WMM) make Wi-Fi more suitable for latency-sensitive applications (such as voice and video); and power saving mechanisms (WMM Power Save) improve battery operation.

Limitations

Spectrum assignments and operational limitations are not consistent worldwide: most of Europe allows for an additional two channels beyond those permitted in the U.S. for the 2.4 GHz band (1–13 vs. 1–11), while Japan has one more on top of that (1–14). Europe, as of 2007, was essentially homogeneous in this respect.

A Wi-Fi signal occupies five channels in the 2.4 GHz band; any two channels whose channel numbers differ by five or more, such as 2 and 7, do not overlap. The oft-repeated adage that channels 1, 6, and 11 are the only non-overlapping channels is, therefore, not accurate; channels 1, 6, and 11 do, however, comprise the only group of three non-overlapping channels in the U.S.

Equivalent isotropically radiated power (EIRP) in the EU is limited to 20 dBm (100 mW).

The current ‘fastest’ norm, 802.11n, uses double the radio spectrum compared to 802.11a or 802.11g. This means there can only be one 802.11n network on 2.4 GHz band without interference to other WLAN traffic.

The Internet protocol was designed for a wired network in which packet loss due to noise is very rare and packets are lost almost exclusively due to congestion. On a wireless network, noise is common. This difference causes TCP to greatly slow or break transmission when noise is significant, even when most packets are still arriving correctly.^[^{citation needed}^]

Reach

See also: Long-range Wi-Fi.

Wi-Fi networks have limited range. A typical wireless router using 802.11b or 802.11g with a stock antenna might have a range of 32 m (120 ft) indoors and 95 m (300 ft) outdoors. IEEE 802.11n, however, can exceed that range by more than two times.^[32] Range also varies with frequency band. Wi-Fi in the 2.4 GHz frequency block has slightly better range than Wi-Fi in the 5 GHz frequency block. Outdoor ranges, through use of directional antennas, can be improved with antennas located several kilometres or more from their base. In general, the maximum amount of power that a Wi-Fi device can transmit is limited by local regulations, such as FCC Part 15 in USA.

Due to reach requirements for wireless LAN applications, Wi-Fi has fairly high power consumption compared to some other standards. Technologies such as Bluetooth (designed to support wirelessPAN applications) provide a much shorter propagation range of <10m^[33] and so in general have a lower power consumption. Other low-power technologies such as ZigBee have fairly long range, but much lower data rate. The high power consumption of Wi-Fi makes battery life in mobile devices a concern.

Researchers have developed a number of “no new wires” technologies to provide alternatives to Wi-Fi for applications in which Wi-Fi’s indoor range is not adequate and where installing new wires (such as CAT-5) is not possible or cost-effective. For example, the ITU-T G.hn standard for high speed Local area networks uses existing home wiring (coaxial cables, phone lines and power lines). AlthoughG.hn does not provide some of the advantages of Wi-Fi (such as mobility or outdoor use), it’s designed for applications (such as IPTV distribution) where indoor range is more important than mobility.

Due to the complex nature of radio propagation at typical Wi-Fi frequencies, particularly the effects of signal reflection off trees and buildings, algorithms can only approximately predict Wi-Fi signal strength for any given area in relation to a transmitter.^[34] This effect does not apply equally to long-range Wi-Fi, since longer links typically operate from towers that broadcast above the surrounding foliage.

]Mobility

The very limited practical range of Wi-Fi essentially confines mobile use to such applications as inventory-taking machines in warehouses or in retail spaces, barcode-reading devices at check-out stands, or receiving/shipping stations. Mobile use of Wi-Fi over wider ranges is limited, for instance, to uses such as in an automobile moving from one hotspot to another. Other wireless technologies are more suitable.^[^{citation needed}^]

Data security risks

The most common wireless encryption-standard, Wired Equivalent Privacy (WEP), has been shown to be easily breakable even when correctly configured. Wi-Fi Protected Access (WPA and WPA2) encryption, which became available in devices in 2003, aimed to solve this problem. Wi-Fi access points typically default to an encryption-free (open) mode. Novice users benefit from a zero-configuration device that works out-of-the-box, but this default does not enable any wireless security, providing open wireless access to a LAN. To turn security on requires the user to configure the device, usually via a software graphical user interface (GUI). On unencrypted Wi-Fi networks connecting devices can monitor and record data (including personal information), but such networks may use other means of protection, such as a VPN or secure Hypertext Transfer Protocol (HTTPS) over Transport Layer Security.

Interference

For more details on this topic, see Electromagnetic interference at 2.4 GHz.

Wi-Fi connections can be disrupted or the internet speed lowered by having other devices in the same area. Many 2.4 GHz 802.11b and 802.11g access-points default to the same channel on initial startup, contributing to congestion on certain channels. Wi-Fi pollution, or an excessive number of access points in the area, especially on the neighboring channel, can prevent access and interfere with other devices’ use of other access points, caused by overlapping channels in the 802.11g/b spectrum, as well as with decreased signal-to-noise ratio (SNR) between access points. This can become a problem in high-density areas, such as large apartment complexes or office buildings with many Wi-Fi access points.

Additionally, other devices use the 2.4 GHz band: microwave ovens, ISM band devices, security cameras, ZigBee devices, Bluetooth devices and (in some countries) Amateur radio, video senders, cordless phones and baby monitors, all of which can cause significant additional interference. It is also an issue when municipalities^[35] or other large entities (such as universities) seek to provide large area coverage.

Hardware

USB wireless adapter

A wireless access point (WAP) connects a group of wireless devices to an adjacent wired LAN. An access point resembles a network hub, relaying databetween connected wireless devices in addition to a (usually) single connected wired device, most often an ethernet hub or switch, allowing wireless devices to communicate with other wired devices.

Wireless adapters allow devices to connect to a wireless network. These adapters connect to devices using various external or internal interconnects such as PCI, miniPCI, USB, ExpressCard, Cardbus and PC Card. As of 2010, most newer laptop computers come equipped with internal adapters. Internal cards are generally more difficult to install.

Wireless routers integrate a Wireless Access Point, ethernet switch, and internal router firmware application that provides IP routing, NAT, and DNSforwarding through an integrated WAN-interface. A wireless router allows wired and wireless ethernet LAN devices to connect to a (usually) single WAN device such as a cable modem or a DSL modem. A wireless router allows all three devices, mainly the access point and router, to be configured through one central utility. This utility is usually an integrated web server that is accessible to wired and wireless LAN clients and often optionally to WAN clients. This utility may also be an application that is run on a desktop computer, as is the case with as Apple’s AirPort, which is managed with theAirPort Utility on Mac OS X and Microsoft Windows.^[36]

Wireless network bridges connect a wired network to a wireless network. A bridge differs from an access point: an access point connects wireless devices to a wired network at the data-link layer. Two wireless bridges may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes.

Wireless range-extenders or wireless repeaters can extend the range of an existing wireless network. Strategically placed range-extenders can elongate a signal area or allow for the signal area to reach around barriers such as those pertaining in L-shaped corridors. Wireless devices connected through repeaters will suffer from an increased latency for each hop. Additionally, a wireless device connected to any of the repeaters in the chain will have a throughput limited by the “weakest link” between the two nodes in the chain from which the connection originates to where the connection ends.

Distance records

Distance records (using non-standard devices) include 382 km (237 mi) in June 2007, held by Ermanno Pietrosemoli and EsLaRed of Venezuela, transferring about 3 MB of data between the mountain-tops of El Águila and Platillon.^[37]^[38] The Swedish Space Agency transferred data 420 km (260 mi), using 6 watt amplifiers to reach an overhead stratospheric balloon.^[39]

Embedded systems

Embedded serial-to-Wi-Fi module

Increasingly in the last few years (particularly as of 2007), embedded Wi-Fi modules have become available that incorporate a real-time operating system and provide a simple means of wirelessly enabling any device which has and communicates via a serial port.^[40] This allows the design of simple monitoring devices. An example is a portable ECG device monitoring a patient at home. This Wi-Fi-enabled device can communicate via the Internet.^[41]

These Wi-Fi modules are designed^[^{by whom?}^] so that implementers need only minimal Wi-Fi knowledge to provide Wi-Fi connectivity for their products.

Network security

The main issue with wireless network security is its simplified access to the network compared to traditional wired networks such as ethernet.^[^{citation needed}^]With wired networking one must either gain access to a building (physically connecting into the internal network) or break through an external firewall. Most business networks protect sensitive data and systems by attempting to disallow external access. Enabling wireless connectivity provides an attack vector, particularly if the network uses inadequate or no encryption.^[42]

An attacker who has gained access to a Wi-Fi network router can initiate a DNS spoofing attack against any other user of the network by forging a response before the queried DNS server has a chance to reply.^[43]

Securing methods

A common but unproductive measure to deter unauthorized users involves suppressing the access point’s SSID broadcast. This is ineffective as a security method because the SSID is broadcast in the clear in response to a client SSID query. Another unproductive method is to only allow computers with knownMAC addresses to join the network.^[44] But, intruders can defeat this method because they can often (though not always) set MAC addresses with minimal effort (MAC spoofing). If eavesdroppers have the ability to change their MAC address, then they may join the network by spoofing an authorized address.

Wired Equivalent Privacy (WEP) encryption was designed to protect against casual snooping, but is now deprecated. Tools such as AirSnort or Aircrack-ngcan quickly recover WEP encryption keys. Once it has seen 5-10 million encrypted packets, AirSnort can determine the encryption password in under a second;^[45] newer tools such as aircrack-ptw can use Klein’s attack to crack a WEP key with a 50% success rate using only 40,000 packets.

To counteract this in 2002, the Wi-Fi Alliance approved Wi-Fi Protected Access (WPA) which uses TKIP as a stopgap solution for legacy equipment. Though more secure than WEP, it has outlived its designed lifetime and has known attack vectors.

In 2004, the IEEE ratified the full IEEE 802.11i (WPA2) encryption standards. If used with a 802.1X server or in pre-shared key mode with a strong and uncommon passphrase and uncommon SSID (Used to salt the password) WPA2 is still considered secure by many IT professionals.^[^{by whom?}^]

Piggybacking

Main article: Piggybacking (Internet access)

Piggybacking refers to access to a wireless Internet connection by bringing one’s own computer within the range of another’s wireless connection, and using that service without the subscriber’s explicit permission or knowledge.

During the early popular adoption of 802.11, providing open access points for anyone within range to use was encouraged^[^{by whom?}^] to cultivate wireless community networks,^[46] particularly since people on average use only a fraction of their downstream bandwidth at any given time.

Recreational logging and mapping of other people’s access points has become known as wardriving. Indeed, many access points are intentionally installed without security turned on so that they can be used as a free service. Providing access to one’s Internet connection in this fashion may breach the Terms of Service or contract with the ISP. These activities do not result in sanctions in most jurisdictions; however, legislation and case law differ considerably across the world. A proposal to leave graffiti describing available services was called warchalking.^[47] A Florida court case determined that owner laziness was not to be a valid excuse.^[48]

Piggybacking often occurs unintentionally, since most access points are configured without encryption by default and operating systems can be configured to connect automatically to any available wireless network. A user who happens to start up a laptop in the vicinity of an access point may find the computer has joined the network without any visible indication. Moreover, a user intending to join one network may instead end up on another one if the latter has a stronger signal. In combination with automatic discovery of other network resources (see DHCP and Zeroconf) this could possibly lead wireless users to send sensitive data to the wrong middle-man when seeking a destination (see Man-in-the-middle attack). For example, a user could inadvertently use an insecure network to log in to a website, thereby making the login credentials available to anyone listening, if the website uses an insecure protocol such as HTTP.

Health issues

A small percentage of Wifi users have reported adverse health issues after repeat exposure and use of Wifi,^[49] though there has been no publication of any effects being observable in double-blinded studies. The ubiquity of WiFi has led to calls for more research into the effects of “electronic smog”.^[50]

One study speculated that “laptops (WiFi mode) on the lap near the testes may result in decreased male fertility”.^[51] Another study found decreased working memory among males during Wi-Fi exposure.^[52]

In a BBC article,^[53] the World Health Organization (WHO) says “there is no risk from low level, long-term exposure to wi-fi networks” and the United Kingdom’s Health Protection Agency reports that exposure to Wi-Fi for a year results in “same amount of radiation from a 20-minute mobile phone call.”

How WiFi Phones Work

It’s a proverb that there’s nothing new under the sun, and the recent surge in inexpensive Wi-Fi wireless gateways that build clouds of wireless access that bridge to each other without a wire in sight proves the principle. The standard that allows this new integrated feature in cheap access points appears way back in the revised IEEE 802.11 specification from 1999, which helped start this current revolution.

Wireless bridging comes in two forms: the one we’re accustomed to talking about generically, in which a Wi-Fi signal is bridged via an internal router in an access point or gateway to a wired network. The wired network can be as plain as a connection to an external or internal dial-up, DSL, or cable modem. Although this is often called wireless bridging, it’s really wireless-to-wired.

The second form is the “new” flavor, however: wireless-to-wireless bridging using the Wireless Distribution System (WDS). WDS allows packets to pass from one wireless access point to another, just as if the access points were ports on a wired Ethernet switch. WDS bypasses the kind of magical kludgery that Linksys offered with its WET11 bridge or with the WAP11 in pairs or as a bridge/AP combination.

The original WAP11, and similar bridge/access points made by other companies for the consumer market, could provide point-to-point or even point-to-multipoint bridging, but had to be locked into a bridge-only mode. They couldn’t function as an access point and a bridge at the same time, a limitation that newer devices with WDS support have avoided. (It’s still an option if you just want to bridge without offering client access.)

The WET11 and even the newer WET54G work singly, by contract, and they can connect to any access point. They achieve their ability to bridge a number of wired devices—from 30 to 50—by masquerading the wired devices’ MAC (Media Access Control) addresses as their own. This can cause some network confusion, as MAC addresses are meant to be unique, typically.

WDS doesn’t use MAC masquerading nor does it require supporting devices to lock themselves into a bridge-only mode, although some makers are still choosing that option. WDS-enabled access points can service local clients while also bridging traffic to other, similarly enabled access points in a hierarchical tree. One unit can act as a master gateway or the “point” in a point-to-multipoint network; the master is the unit that is typically configured to be connected to the Internet or some sort of robust backbone. Other WDS-equipped gateways all point to each other in a star configuration.

WDS relies on a previously underused element of the Frame Control Field for IEEE 802.11b. With the distribution system (DS) bits both set to 1, the client can provide not just its source address (SA) and the destination address of a frame (DA), but also the addresses of the two intermediate wireless gateways (transmitting and receiving or TA and RA) that are bridging the connection. The WDS-enabled access points broadcast MAC messages across all connected nodes allowing all clients to see all adapters on all connected wireless and wired networks.

You can read more of the particulars on these framing details in “802.11 Wireless Networks: The Definitive Guide,” pages 56-60, or in section 7.1.3 of the specification, which is a free download.

Let’s take a typical example. Jim is using a laptop in Building A, while Jane administers a cable modem in Building B. Building A and B are linked by Access Point 1 and 2 via WDS. Access Point 2 is also a relay, which connects with Access Point 3, which is connected via Ethernet to the cable modem that Jane runs.

Jim tries to access the Internet. His wireless adapter transmits a frame with the destination address of Jane’s cable modem. Access Point 1 knows that Jane’s cable modem is on the other side of its bridge based on its MAC table. It rewrites the frame to include itself as the TA and Access Point 2 as the RA.

When Access Point 2, the relay, receives the frame, it knows that the destination is really on Access Point 3, so it rewrites the frame again, turning itself into the TA and Access Point 3 into the RA. The frame arrives at that final access point and hits the cable modem.

In a star configuration, each access point has a list of other WDS-equipped access points that it’s bridging with.

The excitement about this technology comes from three factors: a WDS gateway can act as an AP and a bridge in a single box; WDS is standard, although interoperability isn’t being tested by manufacturers yet; and WDS is cheap, with Buffalo offering its WLA-G54 for as little as $100 street price. In the past, expensive enterprise devices either involved standalone bridges or pricey combined units that worked only with other proprietary gear.

Apple also offers WDS in its AirPort Extreme Base Station ($200 or $250, depending on features); Linksys is using WDS in its revised bridging AP, the WAP54G, but the unit has to be locked into bridge mode even with WDS turned on. (Both the Buffalo and Apple units can be set to ignore local clients and just act as bridges.)

You might want to use WDS in a variety of common scenarios that would otherwise require expensive or unnecessary Ethernet cabling. If you needed two access points to serve your house, for instance, and didn’t want to run Ethernet between them, WDS is an able substitute.

It’s also a cheaper and simpler way to provide blanket coverage. Attach some sectorized antennas on opposite ends of an open courtyard or park and use WDS to avoid having to put backhaul or backbone between the two units, even while both of them can offer the optimum strength for client connections.

Remember, however, that the stronger the antenna’s signal, the more directional it becomes. If you wanted to use WDS to span a mile between your home and that of a friend, you could certainly do so, but the WDS devices wouldn’t be able to also serve up access to clients in their vicinity. WDS is more about building a cloud than a long-haul system, and stronger omnidirectional antennas could be part of that.

Still, a pair of Buffalo WLA-G54′s talking WDS might be easier to manage than a pair of WAP54Gs, and more easily swapped in and out if equipment problems emerge.

All of the current home gateways are single network interface devices, which means that the WDS backhaul subtracts from your pool of bandwidth. Even worse, WDS bridges and master units must work over the same Wi-Fi channel, which increases interference and reduces throughput. With enough local devices, you’re sacrificing a lot of bandwidth for routine traffic.

The 802.11g factor does help out, though. If you have the usual DSL speeds on your Internet backhaul, then cutting 20-odd Mbps of net throughput in an ideal 802.11g environment down to a third or fourth or a fifth still won’t hold up traffic upstream or downstream. It may be less ideal in offices, homes, or dorms in which local data needs exceed the equivalent of 10Base-T. (In that case, you could use back-to-back bridged connections in which you use a short wired backbone between two access points and set the back-to-back set to a different channel.)

Still, Wi-Fi traffic is usually in bursts, so even a solid stream of data that’s being relayed from one gateway to another via WDS and starting and ending at a wireless client should be able to achieve 5 to 10 Mbps.

A looming question with WDS is interoperability. WDS isn’t part of the Wi-Fi certification program, and it doesn’t appear as though access points made by different companies use the identical approach for configuration, nor is any maker guaranteeing their gear works with anyone else’s.

I was able to turn an Apple AirPort Extreme Base Station into a master WDS node (see Figure 1), and it automatically discovered a Buffalo WLA-G54 on the same network that had its WDS mode enabled (Figure 2). I entered the AirPort address into the Buffalo list of WDS access points, and selected the Buffalo on the AirPort’s list. After reboots, they both spoke to each other with no hiccups.

Figure 2: WLA-G54 Configuration

Mac users might find this information especially appealing, as they can use the WLA-G54 as a cheap alternative to the more expensive AirPort Extreme Base Station. The WLA-G54 is an access point with no gateway features like DHCP service, making it the perfect WDS extender.

WDS can pull some of the complexity, expense, and copper out of any new installation, and it’s worth thinking about whether when you’re building a home, office, or neighborhood network whether a WDS access point, bridge, or relay could fit the pieces together with less stress.

The next generation of WDS devices clearly need two radios, and some enterprise equipment has already taken that tack. Vivato recently announced a two-radio access point meant to fill in the gaps or edges of service that it can offer with its phased-array antenna design; they use WDS for the switch-to-access point communication. Tropos Networks has a mesh system for backhaul that relies on WDS, while an optional second radio offers client wireless access.

It might take a leap of faith for the consumer companies to add two radios, but with the cost of a gateway with WDS in the $100 range, a $175 device with two cards and separate antennas for back haul could be part of the next big expansion of wireless networks.

WiFi Phones

From their user interface to how they work, WiFi phones are a lot like cell phones . Like a basic cell phone, a WiFi phone has a printed circuit board (PCB) that connects:

A processor
A speaker and a microphone
A numeric keypad and other function keys
A lithium ion battery
A screen, usually a liquid crystal display (LCD)
An antenna
Memory

Both types of phones also send and receive signals as radio waves. The difference is that WiFi phones use different frequencies than cellular phones do. Cell phones use 824-MHz to 894-MHz frequency bands. WiFi phones that use the 802.11b or 802.11g standards transmit at 2.4 GHz. Phones that use the 802.11a standard transmit at 5 GHz.

When you make a call on a WiFi phone, you dial the number of the person you want to call, just like you would with a cell phone. If you’re calling another VoIP user, you may enter a VoIP address instead of a phone number, depending on the service provider’s requirements.

The phone translates the number you dial into packets of data. It uses radio waves to transmit the packets to a wireless receiver. The receiver passes the information over the Internet to the call processor like an ordinary VoIP call. When you begin your conversation, the phone transmits your voice in packets of data as well. Your voice travels just like it does in a VoIP call, although the specifics can differ from one provider to another.

· Does WiMAX Threat WiFi?

Abstract

WiFi (Wireless Fidelity) or often called as WLAN (Wireless Local Area Network) is one of wireless broadband technologies that has been mature. WiFi technology maturity proved by the standardization that has been agreed since long time ago (IEEE 802.11), many supports from vendor, and has been used by various groups.

WiFi network usage has been used by many companies or individuals both for private network and for public area or hotspot. Beside many vendors that can provide Access Point also supported by terminal vendor such as computer, note book, PDA, and handphone that has been completed with WiFi interface inside. Plus the price is reachable, so WiFi spread very quickly. Nowadays, almost in every corner in town or airport has been used WiFi device for hotspot service.

The next advanced of broadband wireless technology is WiMAX (Wireless Interoperability for Microwave Access). The technology almost similar with WiFi which added by capability in coverage area, QoS, NLOS (Non Line of Sight), Security, and the other features.

With the condition above, surely it will cause many questions from the observer and telecommunication player, will WiMAX be competitor for WiFi or can it used to support WiFi in field? The article will try to analyze from two points of view both WiMAX for supporting WiFi and the other side WiMAX with WiFi will give service together.

WiFi and WiMAX Application

With capabilities of WiFi (wireless LAN), user capable connect to the internet network wirelessly. The characteristic very suitable if it used by user in office area, hospital, campus, hotel, airport, and house.

Thereby, WiFi usage generally can be mapped such as below:

Picture 1. Various Wireless LAN applications

It is so different between WiFi and WiMAX. Various applications that can be reached by using WiMAX are:

- Backhaul application

For backhaul application, WiMAX can be used to backhaul WiMAX itself, backhaul hotspot, and the other technology backhaul.

Backhaul WiMAX

In WiMAX context as backhaul of WiMAX, the application resemble with BTS function as repeater. The aim is to widen coverage of WiMAX.

Backhaul Hotspot

Generally, hotspot many use ADSL lines as the backhaul to connect the internet connection. With limited cable network, WiMAX can be used as backhaul hotspot.

Backhaul for another technologies

Another technologies backhaul, WiMAX can be used for cellular backhaul. Picture 2 Illustrates WiMAX for connecting MSC/BSC to cellular BTS.

- Broadband Access

WiMAX can be used as Last Mile technology to serve broadband necessary of subscribers. With more capability in QoS (Quality of Service) WiMAX can be used to serve housing and business subscriber with different service.

- Personal Broadband

WiMAX as personal broadband service provider can be differenced into two target markets. There are nomadic and mobile. Detail illustration as follow:

� Nomadic

For nomadic solution, usually mobility level of WiMAX user is not high and if it moves, it will move in low speed. Usually the device is not as simple as mobile application.

� Mobile

For mobile application, user WiMAX better to use WiFi terminal such as notebook, PDA, or smart phone. The mobility levels equal with WiFi level. The difference is in WiMAX use will be used WiMAX card that put on the terminal. Picture 2 illustrates WiMAX for mobile application.

Integration or Overlay

Can be seen from description above about WiFi and WiMAX, the outline is both of them can be integrated and overlay. If they were integrated, it means between WiMAX and WiFi will support each other. Both of them will be synergized to serve bigger and many more subscribers. If they were overlay or overlap in coverage, so they can be functioned to support each other (if they were in one operator) and will be opponent if they were in different operators.

Various configurations that can be applied by WiMAX and WiFi operators if they were integrated as follow:

- as backhaul

The configuration shown as in picture 2. WiFi network will be cost effective than WiFi for the backhaul. By combining these two technologies, WiMAX functioned as backhaul while WiFi connected directly to the subscriber.

Picture 2. WiMAX as WiFi Mesh Network Backhaul (source: Intel).

- as backhaul inter WiFi Mesh Network

In this step, WiMAX has been used directly as part of WiFi Mesh Network. Subscriber Terminal of WiMAX put on Access Point WiFi Mesh Network so WiFi network automatically be more reliable in wider coverage area and reduce cost connection that caused by cable drawing in each AP installation. The configuration shown as picture 3. The solution principally can increase performance and robust of WiFi network.

Picture 4. WiFi and WiMAX Full Integration (source: Intel)

Combination of both technologies platform gives sufficient solution, especially for data communication system that still become problem nowadays. Access to internet network is profitable application. Various innovations can be created such as free internet to houses, connection service in cultural art community, social professions non profit, etc.

Beside integration concept above, between WiMAX and WiFi also can be competitive to get subscribers. It can be happened if WiMAX and WiFi in different operators and give services in one area. WIMAX Application as personal broadband that will cause competition with WiFi.

Thereby, for consumer it will be easier because they can view network appropriate with their needs. The illustration above describes the consumer notebook where it apparently network WiFi (Hotspot) with WiMAX.

For hotspot operator, WiMAX can be used to make penetration of hotspot implementation easy. Beside as customer loyalty, it also can add brand image for meant operator. But, if the operator is different, so the WiMAX will struggle hotspot market which based on WiFi technology. Quality, price, marketing, and the after sales service will determine where the subscriber will choose.

Conclusion

Some things that have to be concluded with description above as follow:

1. WiMAX can be applied for backhaul, broadband access (wireless DSL) and personal broadband while WiFi capable for private application and for public (hotspot).

2. WiMAX and WiFi can be scenario for synergy and can be threat each other if it operated in different operators.

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Filed under: varations of 3g and wi-fi

Precaution at Chat..!!!

sailjamehra — Tue, 23 Aug 2011 15:08:40 +0000

***Chat* *Precautions on Net***

..written by TejasviJain

Contents:

Gmail:-
Introduction to Gmail
How to create an id in gmail
How to start a chat in gmail
Yahoo:-
Introduction to Yahoo
How to create an id in Yahoo
How to start a chat in yahoo
Rediff:-
Introduction to Rediff
How to create an account in rediff
How to chat in Rediff
What is Network chat:-
Precautions to be taken while online chat
Internet Chat room safety tips
Conclusion

Introduction to Gmail:-

Gmail is a free, advertising-supported email service provided by Google. Users may access Gmail as secure webmail, as well via POP3 or IMAP protocols. Gmail was launched as an invitation-only beta release on April 1, 2004 and it became available to the general public on February 7, 2007, though still in beta status at that time. The service was upgraded from beta status on July 7, 2009, along with the rest of the Google Apps suite. As of November 2010, it had 193.3 million users monthly.

Gmail was a project started by Google developer Paul Buchheit several years before it was announced to the public. Initially the software was available only internally as an e-mail client for use only by Google employees. The project was known by the code name Caribou, [citation needed] a reference to a Dilbert comic strip about Project Caribou. Google announced Gmail to the public on April 1, 2004. IMAP support was added on October 24, 2007.

Gmail was ranked second in PC World’s “100 Best Products of 2005″, behind Mozilla Firefox. Gmail also won ‘Honorable Mention’ in the Bottom Line Design Awards 2005. In September 2006, Forbes magazine declared Gmail as the best webmail. In November 2006, Gmail received PC World’s 4 star rating. Gmail has drawn many favorable reviews from users for generous space quotas and unique organization.

Gmail was made available to the public by Google on 1 April 2004, after extensive rumors of its existence during testing. Owing to the April Fool’s Day release, the company’s press release aroused skepticism in the technology world, especially since Google had been known to make April Fool’s jokes in the past, such as Pigeon rank. However, they explained that their real joke had been a press release saying that they would take off shoring to the extreme by putting employees in a “Google Copernicus Center” on the Moon. Jonathan Rosenberg, Google’s vice-president of products, was quoted by BBC News as saying, “We are very serious about Gmail.” Gmail is built on the idea that email can be more intuitive, efficient, and useful.

With an initial storage capacity offer of 1 GB per user, Gmail significantly increased the webmail standard for free storage from the 2 to 4 MB its competitors such as Hotmail offered at that time. Individual Gmail messages, including attachments, may be up to 25 MB, which is larger than many other mail services support. Gmail has a search-oriented interface and a “conversation view” similar to an Internet forum. Gmail is noted by web developers for its pioneering use of AJAX. Gmail runs on Google GFE…

Gmail has changed the face not only of web email but of web applications in general. When Gmail was first shown in 2004 to a substantial audience of beta testers, it was quite different from what consumers had been conditioned to expect from a web application. It was the first time in history that an online email system didn’t require full page reloads every time that you clicked on a new page. You could easily sort and search your mail. Storage was virtually unlimited for most users – and all for free. It’s no wonder why Gmail has grown to become one of the most popular webmail applications.

Before its acquisition by Google, the gmail.com domain name was used by a free e-mail service offered by Garfield.com, online home of the comic strip Garfield. After moving to a different domain, that service has since been discontinued. As of 22 June 2005, Gmail’s canonical URL changed from http://gmail.google.com/gmail/ to http://mail.google. com/mail/. As of November 2010, those who typed in the former URI were redirected to the latter.

In January 2005, Security experts discovered a critical flaw in the handling of Gmail messages that would allow hackers to easily access private e-mails from any Gmail user’s account. This was posted with detailed information to popular technology site Slashdot at 9:23 a.m. PST on 12 January 2005. On 13 January 2005, developers at Gmail announced that they had fixed the problem and that the security flaw had been patched. Despite Gmail’s status as a beta application, concerns were raised among some users who were using Gmail as their primary mail account.

On 1 April 2005, Exactly one year after the initial release, Gmail increased the mailbox size to 2 GB, advertising it as 2GB plus and introduced some other new features, including formatted editing which gave users the option of sending messages in HTML or plain text. On 13 April 2005, Gmail became available in several languages: British English, Dutch, French, German, Italian, Japanese, Korean, Portuguese, Spanish, Russian and simplified and traditional Chinese.

In August 2005, Gmail started offering 100 invitations to some users.[citation needed] On 9 August 2005, Gmail became available in 12 new languages: Bulgarian, Croatian, Greek, Hungarian, Icelandic, Indonesian, Latvian, Serbian, Slovak, Slovenian, Ukrainian and Vietnamese.[citation needed] On 24 August 2005, Google offered a new method of signing up for a Gmail account via mobile phone text messaging. On 17 January 2006, Gmail added a delete button to the menu bar. This now allows users to easily delete their messages. On 7 February 2006, Gmail added the ability for users to chat with others on their contact list when logged into their account. Users have the option to save their chats in a Chat History.

How to create a gmail id:-

v Step 1 -Open the Gmail web site

To create your Gmail account you only need a web browser – the program you are using to read this page – and an internet connection.

Click on the Sign up for Gmail link that is circled in the screenshot and then proceed to the next page to get your free Gmail email address.

Step 2 – Enter all the required information in the “Create an Account” online form

You now need to start filling the form. Once you have entered your first and last names, it is time to choose a login name. This is important as your login name will decide the email address you will get, and in case of a Gmail account, would be your-chosen-login-name@gmail.com. So be sure to pick a login name, also called the username, with care.

v Step 3 – How to choose a login name or username for your email address

Choosing a login name is part art and part common sense. And because it determines what your email address will be, I suggest you spend a little time over it. Since, email addresses need to be unique which means no two people in the world can have the same address, there is no guarantee that your preferred login name would be available – more on this below. The following is my advice and suggestions on how to choose a login or username.

First check if you can get a login name of your name, firstname, lastname, as firstname-lastname or the more popular, firstname.lastname (yes, the period sign can be used in a login name). You can also try out firstnamelastname.. If your name doesn’t work out, seek to couple your name with your profession – such as john.webdeveloper.

Your login name needs to be catchy and at the same time describe you so people are able to recall it without much difficulty and associate it with you.

The availability of a login or user name can be verified by entering it first in the text field and hitting the check availability button.

v Step 4 – Choosing a password for your email

Secure your Gmail email account with a strong password . A combination of uppercase and lowercase letters with some digits thrown in would be a strong enough password. On the right of the text fields in which you enter your password a sort of meter would indicate the strength of the password. You need to enter the password twice and you can leave the “Remember me on this computer” box unchecked.

v Step 5 – Protecting your Gmail account with a security question

You now need to either select a security question from the drop down list or enter one – and you need to provide the answer. This additional security helps in getting your email account password if you forget it. You may also enter a secondary email address but this field is optional, i.e. you can leave it blank. And then after you have read the terms and conditions specified just click on.

How to chat in Gmail:

Steps:

First you have to create an account in gmail by filling all the necessary details after that sign in to gmail
See whether your friend is online. This is indicated by a green dot (yellow if they’re sort of busy, red if they want you to bug off already, and if they’re offline, they’re either really offline or invisible) or a green robot if you have the Android Lab feature installed.
Then, click on their name on the chat list. Sometimes people hide their chat list, so it could be anywhere in your layout. Just look for a box named “Chat”.
Type in anything you want to say. A nice “Hi!” or “Hello!” or “Hey there!” will start off your conversation. Don’t talk about the weather. That’s tacky.
Keep on chatting or do something else. To turn yourself invisible if someone is bugging you, click on your profile and then click “Invisible”. This means that you appear offline when you’re really not.
Enjoy your chat.

v Google Chat window:-

Introduction to Yahoo:-

Yahoo! was founded in January 1994, by Jerry Yang and David Filo. They were Electrical Engineering graduate students at Stanford University when they created a website named “David and Jerry’s Guide to the World Wide Web”. David and Jerry’s Guide to the World Wide Web was a directory of other web sites, organized in a hierarchy, as opposed to a searchable index of pages.

In April 1994, “Jerry’s Guide to the World Wide Web” was renamed “Yahoo!”. The yahoo.com domain was created on January 18, 1995 but even before that, at the end of 1994, Yahoo! had already received one million hits.

“Yahoo” had already been trademarked for barbecue sauce, knives (by EBSCO Industries) and human propelled watercraft (by Old Town Canoe Co.). Therefore, in order to get the trademark, Yang and Filo added the exclamation mark to the name.[12] However, the exclamation mark is often incorrectly omitted when referring to Yahoo! But many people believe that the name is inspired from a Indian song “Yahoo” featuring Shammi Kapoor.

Yahoo! grew rapidly throughout the 90s. Like many search engines and web directories, Yahoo! diversified into a Web portal. It also made many high-profile acquisitions. In the late 1990s, Yahoo!, MSN, Lycos, Excite and other Web portals were growing rapidly. Web portal providers rushed to acquire companies to expand their range of services, in the hope of increasing the time a user stays at the portal

Its stock price skyrocketed during the dot-com bubble; Yahoo! stocks closed at an all-time high of $118.75 a share on 3 January 2000. However, after the dot-com bubble burst, it reached an all-time low of $8.11.

In 2000, Yahoo! began using Google for search results. Over the next four years, it developed its own search technologies, which it began using in 2004. Yahoo! also revamped its mail service to compete with Google’s Gmail in 2007. The company struggled through 2008, with several large layoffs.

On August 27, 2007, Yahoo! released a new version of Yahoo! Mail. It added Yahoo! Messenger integration. (Which included Windows Live Messenger due to the networks’ federation) and free text messages (not necessarily free to the receiver) to mobile phones in the U.S., Canada, India and the Philippines.

In February 2008, Microsoft Corporation made an unsolicited bid to acquire Yahoo! for US$44.6 billion. Yahoo! subsequently formally rejected the bid, claiming that it “substantially undervalues” Yahoo! and was not in the interest of its shareholders. Carol Bartz replaced cofounder Jerry Yang in January 2009.

In July, Microsoft and Yahoo! agreed to a deal that will see Yahoo!’s websites use both Microsoft’s search technology and search advertising.[citation needed]Yahoo! in turn will become the sales team for banner advertising for both companies.[citation needed] While Microsoft will provide algorithmic search results, Yahoo! will control the presentation and personalization of results for searches on its pages.[citation needed]

On July 21, 2009, Yahoo! launched a new version of its front page, called Metro. The new page allows users to customize it through the prominent “My Favorites” panel on the left side and integrate third-party web services and launch them within one page. Such applications include pages of Netflix, E-trade, Facebook, and other sites.

On October 28, 2009 Ms. Bartz told PCWorld that she struggled with the question of what Yahoo is when she took over as CEO in January 2009. After talking to many users in about 10 countries, she said, Yahoo! concluded that users consider it their “home on the Internet. The first logo was used when the company was founded in 1995. It was red and had three icons on each side. Sometimes, the logo is abbreviated with Y!

How to create an account in Yahoo:-

To create a new ID, open the sign up page in a browser or click on the link- Yahoo login. Spot the “Sign up” button/ link and click on it

This loads the Yahoo registration form which is divided into three sections – Personal information, Making a new Yahoo ID and Security information. All fields in this form (except for one) are required to be filled.

Personal Information:

Type in your first and last names, select your gender from the drop down, tell Yahoo your birthday, country and postal code. It is very important that you enter correct information. Why? It may be used to get access to your account in case you forget the login details.

Create a Yahoo ID and choose a password for your account:- As mentioned above, a single ID will let you access all Yahoo services. All email addresses have the format [YOUR-CHOSEN-ID]@somewhere. In case of Yahoo, there are three options for the “somewhere” part – yahoo.com, ymail.com and rocketmail.com.

Yahoo IDs need to be unique – no two people can have the same. Remember, the Yahoo ID you are about to create should describe you in some manner. Ideally, the ID should be your name (first name, last name or a combination of the two), but with millions of Yahoo subscribers it is almost impossible to find such kind available unless, of course, you have an uncommon name. To create a new ID, enter it in the field and then click on the conveniently provided “Check” button to see if it’s available. A Yahoo ID can be 4 to 32 characters long, needs to begin with an alphabet and can include numbers, the underscore and one dot. Yahoo IDs are case-insensitive which means ‘John’, ‘JOHN’ or ‘JoHn’ are all the same.

Once a Yahoo ID has been chosen it’s now time for the password. Both the ID and password are required to access your Yahoo account. Make sure the password is not something people can guess outright and don’t make it so complex that it slips your mind. The password should be 6 to 32 characters and can have alphabet, numbers and symbols. Please bear in mind that Yahoo password is case-sensitive.

Security information:- To regain access to your Yahoo account

This section is VERY important! The password is the key to your account. However, it is not uncommon for people to forget it. I know this because I get tens of email daily from desperate people who have problems in login. The alternate email address and the two security questions will let you regain access to your Yahoo account. Obviously, if you don’t have another email address, leave this field blank and concentrate on the next two.

You need to either select or create two security questions. If you lose the Yahoo account password, you would be required to answer these. ensure the answers are not what people can guess easily.

Get your Yahoo

The last couple of steps are deciphering the wavy text and typing it in the blank field above the image and agreeing to the Yahoo Terms of Service and Privacy Policy. Click on “Create My Account” button to get your Yahoo ID.

How to Chat in Yahoo! :

Instant messaging is now available with Yahoo! email, so you don’t have to download a separate messenger program to chat. It’s convenient if you have an urgent question for a friend who is on your contact list. Smiley face icons show whether the person is online or offline. Send an instant message instead of an email if your friend happens to be online.

Ø Instructions:

Sign on to Yahoo! Mail with your user ID and password. Add the contacts to your list by clicking on Contacts. Then a dialog box will appear in that click on Add contacts in that type the details like email id of whom you want to add you can even add the mobile number of that person but that is optional and then click ok and that person will be added to your contact
Go to the “Contacts” list to see who is online. Find the name of the person you want to communicate with once you know who is online. Click on the name to start a chat session. Or press Ctrl+Shift+A
Wait for the conversation window to appear on your email page. Type your message in the input box at the bottom of the conversation window. Hit “Enter” or the “Send” button next to the input box.
See your messages in the main conversation area, which appears above the message input box in the same conversation window. Find your friend’s replies also in the conversation area.
Receive an incoming chat message while using Yahoo! email. An orange tab with the friend’s name appears, indicating that you have a new chat message. Click on the tab to start the instant conversation. Repeat Step 3 to reply to your friend’s message.
Switch to chat from email if the recipient goes online. A notice appears at the bottom of the email window to indicate that the contact is available to chat. Press the “Chat Now” link that appears with the notice, or click the “Chat” icon at the top of the email to convert it to chat mode. The email window converts to the chat window with your message.

Yahoo Chat window:-

Yahoo Messenger Window:-

Introduction to Rediff:

Rediff.com India is a news, information, entertainment, and shopping portal. It was founded in 1996 as “Rediff on the Net” and is headquartered in Mumbai, India with offices in New Delhi and New York City, USA.

According to Alexa, Rediff is the No. 9 Indian web portal . It has more than 316 employees. 89.1% of the millions of visitors to Rediff.com are from India, while the rest come primarily from the USA (3.4%) and China. In April 2001, Rediff.com acquired and began offering India Abroad. It is ranked 146 on Alexa. Rediff.com was the first website domain name registered in India in 1996. It was launched on February 8, 1997; 14 years ago

Rediffmail.Rediff.com is India’s premier online provider of news, information, communication, entertainment and shopping services with a mission to provide a world-class online consumer experience. Rediff has a registered user base of 45 million users and offers them a breadth of services like Rediff mail, Rediff BOL (Messenger service), Rediff Newshound and matchmaker. Additionally, rediff.com provides an ideal platform for Indians living abroad to connect with one another online through Rediff Connexions; Rediff I-land and Rediff blogs. The Rediff.com United States publishing business primarily consists of the India Abroad newspaper and the Rediff India Abroad website.

Rediff India Abroad website offers information and content and is targeted at the Indian-American community in North America. Rediffmail is the flagship product of Rediff.com. It is one of the most popular web eMail service used by Indians worldwide. Rediffmail offers users a complete outlook desktop experience with features like unlimited storage, instant mail preview, quick attachments of upto 10 MB It supports eleven Indian languages. Rediff Web Search provides a comprehensive directory of information adapted to provide relevant search results. Fare Search is the Rediff’s first vertical search product that allows users to search and compare airfares across domestic carriers for all destinations served. Job Search is vertical search product which allows users to search for jobs across various job sites in India under several categories and locations in India. Image Search is one of the popular search services offered by Rediff.com. Users can search from over 1 billion images share the images with their friends from the system itself. Rediff Product Search allows users to compare products across brands, features, price points, user ratings and check availability of the products in their city at local stores with complete contact details. The service covers more than 16 product categories under electronics Rediff Q & A is social media community platform which allows users to ask and answer questions posed by the Rediff community. The platform encourages participation through recognizing the top performers of the week by featuring them in the ‘Hall of Fame’ section. Rediff iLand: Rediff iLand is a social networking and a blogging platform that empowers users to share and express their views and form a community of like minded users. The platform supports eight Indian languages like Hindi, Marathi, Tamil, Teulgu, Malayalam, Kannada, Bengali and Gujarati, allowing users to blog in the language they are most comfortable in. Rediff Bol instant messenger is a free service that works even on low bandwidths. Users can make PC-to-PC voice phone calls; send SMS to mobile phones in India and create customized avatars and participate in chat rooms. Rediff Mobile offers mobile phone users in India a variety of value added services on the text messaging platform by sending a requesting SMS to 57333, which is the designated code number for Rediff.com as well as on the WAP platform by visiting mobile.rediff.com on the WAP browser.

When it re-launched its website in 2000, Rediff implemented the Akamai Media Delivery (AMD) solution, which provides streaming, download delivery, http content delivery, secure content delivery to address every aspect of Rediff’s business. Akamai has made Rediff’s sites stickier by enabling improved site performance and reliability, while providing a rich variety of relevant and engaging content that encourages users to stay longer at the Web site. According to a recent report, visitors spend an average of 97.7 minutes per month at Rediff.com in comparison to 87 minutes spent per month at Yahoo India. With a registered user base of 45 million, Rediff serves 4 million visitors—largely from India and the U.S.—effortlessly and seamlessly every day.

How to create an acoount in Rediff:-

To create a new ID, open the sign up page in a browser or click on the link- Rediff login. Spot the “Sign up” button/ link and click on it as shown above
This loads the Reidff registration form which is divided into three sections – Personal information, Making a new Rediff ID and Security information. All fields in this form (except for one) are required to be filled.

Personal Information:

Type in your first and last names, select your gender from the drop down, tell Rediff your birthday, country and postal code. It is very important that you enter correct information. Why? It may be used to get access to your account in case you forget the login details.

Create a Rediff ID and choose a password for your account:- All email addresses have the format [YOUR-CHOSEN-ID]@rediff.com.

Rediff IDs need to be unique – no two people can have the same. Remember, the Reidff ID you are about to create should describe you in some manner. Ideally, the ID should be your name (first name, last name or a combination of the two), but with millions of Rediff subscribers it is almost impossible to find such kind available unless, of course, you have an uncommon name. To create a new ID, enter it in the field and then click on the conveniently provided “Check” button to see if it’s available..

Once a Rediff ID has been chosen it’s now time for the password. Both the ID and password are required to access your Rediff account. Make sure the password is not something people can guess outright and don’t make it so complex that it slips your mind. The password should be 6 to 32 characters and can have alphabet, numbers and symbols. Please bear in mind that Yahoo password is case-sensitive.

Security information:- To regain access to your rediff account. This section is VERY important! The password is the key to your account. However, it is not uncommon for people to forget it. I know this because I get tens of email daily from desperate people who have problems in login. The alternate email address and the two security questions will let you regain access to your Yahoo account. Obviously, if you don’t have another email address, leave this field blank and concentrate on the next two.

You need to either select or create two security questions. If you lose the Reidff account password, you would be required to answer these. Ensure the answers are not what people can guess easily.

Get your Rediff ID

The last couple of steps are deciphering the wavy text and typing it in the blank field above the image and agreeing to the Rediff Terms of Service and Privacy Policy. Click on “Create My Account” button to get your Rediff ID.

Rediff Mail Window:

What is online chat (network chat):

Online chat may refer to any kind of communication over the Internet that offers an instantaneous transmission of text-based messages from sender to receiver, hence the delay for visual access to the sent message shall not hamper the flow of communications in any of the directions. Online chat may address as well point-to-point communications as well as multicast communications from one sender to many receivers.

Instrumentation

Online chat in a lesser stringent definition may be primarily any direct text-based one-on-one chat or one-to-many group chat (formally also known as synchronous conferencing), using tools such as instant messengers, Internet Relay Chat, talkers and possibly MUDs. The expression online chat comes from the word chat which means “informal conversation”.

History:

The first dedicated online chat service was the CompuServe CB Simulator in 1980, created by CompuServe executive Alexander “Sandy” Trevor in Columbus, Ohio. Ancestors include network chat software such as UNIX “talk” used in the 1970s.

Chatiquette:

The term chatiquette is a variation of netiquette (chat etiquette) and describes basic rules of online communication. To avoid misunderstandings and to simplify the communication between users in a chat these conventions or guidelines have been created. Chatiquette varies from community to community, generally describing basic courtesy; it introduces new user into the community and the associated network culture. As an example, it is considered rude to write only in upper case, because it looks as if the user is shouting. The word chatiquette has been used in connection with various chat systems (e.g. IRC) since 1995.

Cultural impact:

Despite being virtual, chat can spill into the outside world. There can also be a strong sense of online identity leading to impression of subculture. Compare Internet sociology.

Chats are valuable sources of various types of information, the automatic processing of which is the object of chat/text mining technologies.

Precautions to be taken while online chatting :

Some useful Tips to protect yourself when you use social networking sites

Tip 1: Use Strong Passwords:

Always use passwords that hard to guess (Mix of digits + letters in Upper case and lower case both) for your all accounts. the longer your password, the better.

Never use any common word, your name, spouse, parents, birthdate etc.

Explanation 1:

Week Passwords and be easily hacked using a Brute Force method which do combination of numbers and letters until the real password comes.

Common passwords containing name, birthdate can be easily guessed by your friends, any known to you.

Tip 2: Carefully Click on Links:

Always check the links carefully before clicking on that.

Explanation 2:

To explain the this tip, I am taking to examples. Read the examples carefully.

Ex. 1: Please verify your Account. login here ”http://okrut.com“

Ex. 2: Never or ever fill your account details on such link “http://softwareman21.my3gb.com/Gmail/index.html”.

Ex. 3:” we are upgrading our system. please verify your name, mail id, password etc. etc. before date blah blah here ”http://yahoo.com/“

Ex. 4: check this Link

http://www.softy.com/download/1124524/GmailHacker.exe.html

Did you get what is Wrong here in these 2 Examples? Ok let me explain you.

In Ex. 1: check the spelling of Orkut carefully in that link. It can take you on a Fake Orkut Login page. That is called Phishing attack. As soon as you login through that fake login page the hacker get the login name, password or complete information of your account.

In Ex. 2: This technique is called fishing … People usually used free hosting to do such things. You can notice its start with softwreamn21. (hostingname).com/(then gmail)Gmail/index.html so take care of such links.

In Ex. 3: is there anything wrong? All the spellings are correct. Dear ones, just click on the link, you will understand what’s wrong. Don’t afraid to click. You are safe. It’s just a tutorial to let you learn the things. So click the link.

Got my Point in ex. 3, It’s showing you the link of yahoo. But as you click on it, It redirect you to this site. So always check the link carefully. I recommend you to use “link preview addon” for your browser.

In Ex. 4: check the link carefully. In last the extension is html. But just before html its written exe. Html is written here just to make you fool. So that you click on link. But as soon as you will click, an executable file will be installed into your system.

Tip 3: Never Open Email Attachments without scanning:

Don’t open any email attachment from any unknown person. And if the person is known then also first scan the email attachment before open or download it.

Explanation 3:

Email Attachments can contain Executable Virus files, that can harm your system. These files usually come with extension .vbs, .bat, .exe.

Image files with extension .Jpeg or .gif can also contain virus. Beware, Virus can be integrated with those jpeg files that are also auto executable. As soon as you open the virus infected picture, the virus will be install into your system.

Sometimes the file extensions are hided to make you fool. You can get an attachment with .txt extension (as txt files never contain executables) but in actual extension could be .vbs, .exe, .bat etc… check here for eg:http://en.wikipedia.org/wiki/ILOVEYOU

Word files, Excel Files can also contain macro viruses that are very harmful.

Tip 4: Never get trapped into attractive ads….Download only from reputed Sites.

Attractive ads like:

Jackpot.”You have won $100000″, “You are the lucky member today”, “Free recharge”,

Free screen-savers, Free wallpaper, Free Mouse Icons, Free Smiles

Free computer scan

Free Software

Don’t download any software or anything else from just anywhere. Always check for reputed sites then download.

Explanation 4:

These ads are simply a way to attract you to steal your identity and personal information. As soon as you click

On it, the stealers get into your computer.

Stealers are that which store all the matter you type including your username, password and send the information to the Hacker. The worst thing is these stealers are not come into notice by your antivirus.

Tip 5: Surf Internet From a limited User Account:

Create a limited user account on your system that does not have administrator rights. And surf web only from that limited account.

Explanation 5:

As limited Account does not have administrators right. So if anything does get into your system, it will not change any main functions of your system.

Tip 6: Don’t tell Your IP to unknowns:

Explanation 6:

If you tell your IP to anyone then there may be chance that they can see Files in your system.

Tip 7: Turn off all java and java scripting by default:

Turn of java scripting for your browser by default and only enable it for sites that you know you can trust.

Explanation 7:

This can change your account details, passwords, and can simply hack you.

Tip 8: Never read an unsolicited e-mail:

Do spam unsolicited emails immediately without opening.

Explanation 8:

Coz just by opening mail, the sender can know your IP and probably can hack u!!!

Tip 9: Always use different different passwords:

Explanation 9:

Keep Password different for some important account like paypal or any online banking account, other then your social account’s passwords Try to use different passwords for your all accounts.

Tip 10: Keep your Antivirus Up to date:

Explanation 10:

Antivirus updates contain the definitions of Viruses till date. So if you don’t update it regularly, then there can be chance to get infected your system from a latest coming Virus

Tip 11: Know what you’ve posted about yourself:

Explanation 11:

A common way that hackers break into financial or other accounts is by clicking the “Forgot your password?” link on the account login page. To break into your account, they search for the answers to your security questions,such as your birthday, home town, high school class, or mother’s middle name. If the site allows, make up your own password questions, and don’t draw them from material anyone could find with a quick search.

Tip 12:Choose your social network carefully:

Explanation 12:

Evaluate the site that you plan to use and make sure you understand the privacy policy. Everything you put on a social networking site is permanent. Even if you can delete your account, anyone on the Internet can easily print photos or text or save images and videos to a computer.

Tip 13: Scams. How to protect yourself from scams?

Explanation 13:

When you read email or surf the Internet, you should be wary of scams that try to steal your personal information (identity theft), your money, or both. Scams that use the Microsoft name or names of other well-known companies they include fake email messages or websites that use the Microsoft name. The email message might claim that you have won a Microsoft contest, that Microsoft needs your logon information or password, or that a Microsoft representative is contacting you to help you with your computer. Try to avoid all these scams.

Tip 14: Phishing Scam:

Explanation 14:

Phishing scams often use the official logos of the companies they’re trying to spoof. If you think an email message is a phishing scam, delete it, or type the web addresses directly into your browser, or use your personal bookmarks. Phishing (pronounced “fishing”) is a type of online identity theft. It uses email and fraudulent websites that are designed to steal your personal data or information such as credit card numbers, passwords, account data, or other information. You can also use Microsoft tools to report a suspected phishing scam.

Here is an example of what a phishing scam in an email message might look like.

Tip 15: Use Smart screen Filter:

Explanation:

The Microsoft Smart Screen is designed to help protect you from fraudulent websites that try to steal your personal information. While you surf the Internet, Smart Screen Filter analyzes pages and determines if they have any characteristics that might be suspicious. If it finds suspicious web pages, it shows a yellow warning and advises you to proceed with caution.

Tip 16: Practical advice to increase your privacy online:

Explanation 16:

Think before you share personal information. First, read the website’s privacy policy. Privacy policies should clearly explain what data the website gathers about you, how it is used, shared, and secured, and how you can edit or delete it

Tip 17: Giving out your Personal information:

Explanation 17:

Give out personal information like your real name, phone number and location only when you are reasonably or completely sure what you are doing and who you are talking to. Do not do it right away. Even if they give you a real name and location they can still be totally conning you. Be aware that what you are doing may be involving other innocent people like their family members, spouses or children and may cause real damage without you knowing it. If you find out any of this is the case, cut your losses and walk away. Don’t communicate with them further. It is a no-win situation for you and you can become the cause of more problems

Tip 18: Find out if you suspect anything wrong:

Explanation 18:

Question someone if you suspect something is not right or you find information that doesn’t mesh. If they sound wonderful and perfect, heroic, exceptionally-talented but give you no real proof, be very suspicious. Don’t take their version of proof as the only answer either. Find out answers on your own. Don’t get pulled in. Be aware that online someone can say they are something they aren’t or claim to have skills they don’t. Anyone can do research to make themselves sound convincing.

Tip 19: Cyber bulling:

Explanation 19:

Cyber bulling refers to cruel or bullying messages sent to you online. These might be from former friends or other people you know. They can be irritating and, in some cases, even frightening. If you get these bullying messages online, it’s often better to ignore them rather than answer them. Cyberbullies, just like other bullies, may be angry or disturbed people — and may be looking for attention or a reaction.

Tip 20:-Be skeptical:

Explanation 20:- Don’t believe everything you read online. People may post false or misleading information about various topics, including their own identities. This is not necessarily done with malicious intent; it could be unintentional, an exaggeration, or a joke. Take appropriate precautions, though, and try to verify the authenticity of any information before taking any action.

Tip 21:- Evaluate your settings

Explanation 21:- Take advantage of a site’s privacy settings. The default settings for some sites may allow anyone to see your profile, but you can customize your settings to restrict access to only certain people. There is still a risk that private information could be exposed despite these restrictions, so don’t post anything that you wouldn’t want the public to see. Sites may change their options periodically, so review your security and privacy settings regularly to make sure that your choices are still appropriate.

Internet ‘Chat Room’ Safety Tips

Follow all of the above guidelines, and:

Don’t include any part of your name, date of birth, location, or anything sexually suggestive in your ‘chat’ name.
Don’t go in to private chat rooms.
When choosing an online chat room, be cautious of the chat room name. Stick to chat rooms created by the online service, rather than ‘member created’ rooms.
Don’t say anything in a chat room that you wouldn’t say in public, in front of your parents or friends.
If you start to chat regularly with someone, let an adult or parent know.
Remember, you are in control. If a conversation starts to get strange or make you feel uncomfortable, then leave. Leave the chat room, and log off.
Never meet anyone face to face that you met on the Internet unless you tell a parent or adult first, and they go with you.

8. Don’t think of people you’ve met on the Internet as ‘real life’ friends. They’re just not!

9. Don’t click on links or go to sitesthat you’re not familiar with.
1. Never post a picture of yourself online and never e-mail pictures of yourself to people you don’t know.
2. Never give out your password and make sure it’s something only you know.
3. Don’t respond to ‘flames’- people trying to start an argument, or insults, bad language, etc.

Conclusion:-

Online safety is something which we should take seriously. Chatting online can be both fun and entertaining. It can also be a source of friendship or new relations. There are precautions you need to take when you chat online so that the experience is a safe. Be careful who you trust online and remember that online friends are really strangers. People online, no matter how long you have been talking to them or how friendly they are, may not be who they say they are. Stay in control. Keep your personal information secret when chatting online (name, address, telephone number, mobile number, private email address and picture), even if people ask for this, giving out personal information can make you vulnerable.

Be careful what you say about your friends and their personal info. They’ve told you as a mate, so you shouldn’t pass anything on to people they don’t know Think before you answer private messages. It can be harder to end a conversation in a private chat than in a public chat. A private chat may end up being more personal than you like. Use a nickname, not your real name, and a nickname that is not going to attract the wrong type of attention.

Learn how to keep/save a copy of the conversation in chat – this may be useful if you want to report something. All you really need to do is keep your intelligence about you and trust your judgment. With all the problems you can face online, is it worth it? For most people, the answer is definitely yes. You just need to know where the pitfalls are, use some common sense and caution, and you’ll be in control.

*************************************************************************************

Filed under: Precaution on at Chat..!!!

sailjamehra — Thu, 18 Aug 2011 15:21:46 +0000

DATA DICTIONARY

Directory_Location:

Field Name	Data Type	Width	Constraints
Id	Int	4	PK
District_Name	Varchar	50	Not Null
District_Code	Varchar	50	Not Null

Tables of All Districts in AP (ADB, ATP, CDP, CTR, EG, GTR, HD, KAA, KHM, KNL, KR, MBN, MEK, NGD, NL, NZB, PK, SK, VM, VZM, WG, WL)

Field Name	Data Type	Width	Constraints
Phone_no	Int	4	Not Null
Name	Varchar	100	Not Null
Address	Varchar	200	Not Null
City	Varchar	50
Std_Code	Varchar	10

Baby_Names:

Field Name	Data Type	Width	Constraints
Id	Numeric	9	PK
Name	Varchar	50	Not Null
Meaning	Varchar	200	Not Null

Wap_Telugu_World:

Field Name	Data Type	Width	Constraints
Id	Int	4	PK
Category	Varchar	100	Not Null
Description	Varchar	500	Not Null

Telugu_Panchangam:

Field Name	Data Type	Width	Constraints
Id	Numeric	9	PK
P_Date	Varchar	50	Not Null
P_Day	Varchar	50	Not Null
P_Year	Varchar	50	Not Null
Aayanam	Varchar	50	Not Null
Rutuvu	Varchar	50	Not Null
Tithi	Varchar	50	Not Null
Raahukaalam	Varchar	50
Durmuhurtam	Varchar	50
Varjyam	Varchar	50
Subhasamayalu	Varchar	50
Works	Varchar	50

PROJECT OVERVIEW:

The Main Page:

www.aponmobile.com

Depending upon the HTTP_USER AGENT variable value, if it is not like “MOZILLA” i.e. the access is from the Mobile the page is automatically redirected to:

www.aponmobile.com/wap/contents.aspx

This page contains all the contents with the other internal sub links. The main contents are

Ø Telugu World: This link is to provide all information on Telugu terminologies, Telugu Baby Names, Panchangam (Telugu Astrology)

Ø News: To provide Regional News of three main places Hyderabad, Vizag and Vijayawada in AP.

Ø Ringtones: To download favorite ring tones.

Ø Wallpapers: To download favorite wallpapers.

Ø Games: To download favorite games.

Ø Movie Schedules: To view movie schedules and to book tickets in a theatre.

Ø Applications: Different applications, AP Telephone Directory being one of them.

Ø Hutch Privileges: Information on different privileges HUTCH is providing to its users.

This page once visited writes the accessed mobile number into the Wap Access table. Using Server variable “MSISDN” value can get the mobile number.

Telugu World:

www.aponmobile.com/wap/telugu/telugucate.aspx

This page contains three sub links:

Panchangam Bay Names Telugu World

Panchangam Page:

www.aponmobile.com/wap/telugu/panchangam.aspx

This page once visited gives the panchangam the Telugu astrological information of the current day.

Baby Names Page:

www.aponmobile.com/wap/telugu/babynames.wml

This page is meant for searching for Telugu baby names starting with a letter and their meanings. This page asks for the starting letter of the name. The restriction of the field is set by using the attribute for input format = ”A”. This restricts the user to enter one Capital letter.

Baby Name Results Page:

www.aponmobile.com/wap/telugu/babynames.aspx

On searching and finding if there are any Telugu baby names (with meanings) present will give this page in cards (otherwise this page will not be loaded in many mobiles giving the error that the page size is too large to load.) if more results are found else if not found appropriate message will be given.

Telugu World

www.aponmobile.com/wap/telugu/teluguworld.aspx

This page is meant to help people learn Telugu terminologies and other info relates to Telugu like Ruthuvulu (Telugu Seasons) etc. Once a user clicks a link in this he goes to the description page.

Telugu World Description Page:

www.aponmobile.com/wap/telugu/teluguworlddetails.aspx

In this the description related to the link clicked in the Telugu world is shown.

Applications Page:

www.aponmobile.com/wap/applications/application.aspx

In this page we can see other applications list with Telephone Directory Link.

Directory Welcome Page:

www.aponmobile.com/wap/applications/applicationwelcome.aspx

This page gives the welcome message depending upon the selected application. In the present context it welcomes to the directory service. Once the next link is clicked it takes us to the Directory Application’s main Page.

Directory Main Page

www.aponmobile.com/wap/applications/directory/main.aspx

In this a list of Districts in AP are shown. Here you have to select an appropriate district, which takes us to the search option page.

Search Option Page

www.aponmobile.com/wap/applications/directory/Searchoption.aspx

In this option is given to search whether by number or Name. On clicking Next it takes us to Search Screen.

Search Page

www.aponmobile.com/wap/applications/directory/Search.aspx

Depending upon your search option in the previous screen you will get two inputs for search by number for telephone number and std code or one input box to enter Name. With constraints for Number as format = “*N” or for Name format = “*A”.

Directory Result Page

www.aponmobile.com/wap/applications/directory/Directory.aspx

If exact Name or number is found u will get the result. Otherwise appropriate message is given. U can see both types of searches done in the screens both by name and number.

History

The Phone.com, Nokia, Ericsson and other companies began developing their own wireless standards independent of each other. Soon they realized that it would make more sense to focus development around a common standard. They all wanted to establish a common format for Internet transfers to mobile phones, without having to customize the Internet pages for the particular display on every different mobile telephone or personal organizer. This led to the birth of the WAP Forum. With the WAP Forum they were able to find such a protocol.

How does it work?

To access the Internet on your mobile phone you will need a WAP enabled mobile phone from your telecommunications vendor. The regular mobile phone would not be able to access the net, as it does not yet understand the net. You will also require an ISP connection to access to the net. Your mobile service provider enables data and fax. Last but not the least configures your WAP mobile phones to access the WAP sites.

What is WAP?

The wireless industry came up with the idea of WAP. The point of this standard was to show Internet contents on wireless clients, like mobile phones.

WAP stands for Wireless Application Protocol
WAP is an application communication protocol
WAP is used to access services and information
WAP is for handheld devices such as mobile phones
WAP is a protocol designed for micro browsers
WAP enables the creating of web applications for mobile devices.
WAP uses the mark-up language WML (not HTML)
WML is defined as an XML 1.0 application
The Wireless Application Protocol

The WAP protocol is the leading standard for information services on wireless terminals like digital mobile phones. The WAP standard is based on Internet standards (HTML, XML and TCP/IP). It consists of a WML language specification, a WML Script specification, and a Wireless Telephony Application Interface (WTAI) specification.

The WAP Forum, founded in 1997 by Ericsson, Motorola, Nokia, and Unwired Planet, publishes WAP. Forum members now represent over 90% of the global handset market, as well as leading infrastructure providers, software developers and other organizations.

WAP Micro Browsers

To fit into a small wireless terminal, WAP uses a Micro Browser. A Micro Browser is a small piece of software that makes minimal demands on hardware, memory and CPU. It can display information written in a restricted mark-up language called WML. The Micro Browser can also interpret a reduced version of JavaScript called WMLScript.

What is WML?

WML stands for Wireless Markup Language. It is a mark-up language inherited from HTML, but WML is based on XML, so it is much stricter than HTML.WML is used to create pages that can be displayed in a WAP browser. Pages in WML are called DECKS. Decks are constructed as a set of CARDS. What is WMLScript?. WML uses WMLScript to run simple code on the client. WMLScript is a light JavaScript language. However, WML scripts are not embedded in the WML pages. WML pages only contain references to script URLs. WML scripts need to be compiled into byte code on a server before they can run in a WAP browser.

WAP Homepages

WAP homepages are not very different from HTML homepages. The markup language used for WAP is WML (Wireless Markup Language). WML uses tags – just like HTML – but the syntax is stricter and conforms to the XML 1.0 standard. WML pages have the extension *.WML, just like HTML pages have the extension *.HTML.

WML Tags

WML is mostly about text. Tags that would slow down the communication with handheld devices are not a part of the WML standard. The use of tables and images is strongly restricted. Since WML is an XML application, all tags are case sensitive ( is not the same as ), and all tags must be properly closed.

WML Decks and Cards

WML pages are called DECKS. They are constructed as a set of CARDS, related to each other with links. When a WML page is accessed from a mobile phone, all the cards in the page are downloaded from the WAP server. Navigation between the cards is done by the phone computer – inside the phone – without any extra access trips to the server.

The Wireless Markup Language (WML)

Introduction

WML is a markup language that is based on XML (eXtensible Markup Language). The official WML specification is developed and maintained by the WAP Forum, an industry-wide consortium founded by Nokia, Phone.com, Motorola, and Ericsson. This specification defines the syntax, variables, and elements used in a valid WML file. The actual WML 1.1 Document Type Definition (DTD) is available for those familiar with XML at:

http://www.wapforum.org/DTD/wml_1.1.xml

A valid WML document must correspond to this DTD or it cannot be processed.

Understanding the Wireless Markup Language

WML is based on XML, a markup language that has garnered enormous support due its ability to describe data (HTML, meanwhile, is used to describe the display of data…a big difference). While HTML predefines a “canned” set of tags guaranteed to be understood and displayed in a uniform fashion by a Web browser, XML allows the document creator to define any set of tags he or she wishes to. This set of tags is then grouped into a set of grammar “rules” known as the Document Type Definition, or DTD. As mentioned earlier, the DTD used to define WML is located at:

http://www.wapforum.org/DTD/wml_1.1.xml

If a phone or other communications device is said to be WAP-capable, this means that it has a piece of software loaded onto it (known as a micro browser) that fully understands how to handle all entities in the WML 1.1 DTD.

The first statement within an XML document is known as a prolog. While the prolog is optional, it consists of two lines of code: the XML declaration (used to define the XML version) and the document type declaration (a pointer to a file that contains this document’s DTD). A sample prolog is as follows:

Following the prolog, every XML document contains a single element that contains all other sub elements and entities. Like HTML all elements are bracketed by the

and

characters.

As an example: datadatadata. There can only be one document element per document. With WML, the document element is ; all other elements are contained within it.

The two most common ways to store data within an XML document are elements and attributes. Elements are structured items within the document that are denoted by opening and closing element tags. Elements can also contain sub-elements as well. Attributes, meanwhile, are generally used to describe an element. As an example, consider the following code snippet:

Please select your user name.

In the code above, the card element contains the id and title attributes. (On a side note, a comment in WML must appear between the tags

Valid WML Elements

WML predefines a set of elements that can be combined together to create a WML document. These elements include can be broken down into two groups: the Deck/Card elements and the Event elements.

Deck/Card Elements

wml

card

template

head

access

Mobile Application

sailjamehra — Wed, 10 Aug 2011 05:50:26 +0000

DATA DICTIONARY

Directory_Location:

Field Name	Data Type	Width	Constraints
Id	Int	4	PK
District_Name	Varchar	50	Not Null
District_Code	Varchar	50	Not Null

Tables of All Districts in AP (ADB, ATP, CDP, CTR, EG, GTR, HD, KAA, KHM, KNL, KR, MBN, MEK, NGD, NL, NZB, PK, SK, VM, VZM, WG, WL)

Field Name	Data Type	Width	Constraints
Phone_no	Int	4	Not Null
Name	Varchar	100	Not Null
Address	Varchar	200	Not Null
City	Varchar	50
Std_Code	Varchar	10

Baby_Names:

Field Name	Data Type	Width	Constraints
Id	Numeric	9	PK
Name	Varchar	50	Not Null
Meaning	Varchar	200	Not Null

Wap_Telugu_World:

Field Name	Data Type	Width	Constraints
Id	Int	4	PK
Category	Varchar	100	Not Null
Description	Varchar	500	Not Null

Telugu_Panchangam:

Field Name	Data Type	Width	Constraints
Id	Numeric	9	PK
P_Date	Varchar	50	Not Null
P_Day	Varchar	50	Not Null
P_Year	Varchar	50	Not Null
Aayanam	Varchar	50	Not Null
Rutuvu	Varchar	50	Not Null
Tithi	Varchar	50	Not Null
Raahukaalam	Varchar	50
Durmuhurtam	Varchar	50
Varjyam	Varchar	50
Subhasamayalu	Varchar	50
Works	Varchar	50

PROJECT OVERVIEW:

The Main Page:

www.aponmobile.com

Depending upon the HTTP_USER AGENT variable value, if it is not like “MOZILLA” i.e. the access is from the Mobile the page is automatically redirected to:

www.aponmobile.com/wap/contents.aspx

This page contains all the contents with the other internal sub links. The main contents are

Ø Telugu World: This link is to provide all information on Telugu terminologies, Telugu Baby Names, Panchangam (Telugu Astrology)

Ø News: To provide Regional News of three main places Hyderabad, Vizag and Vijayawada in AP.

Ø Ringtones: To download favorite ring tones.

Ø Wallpapers: To download favorite wallpapers.

Ø Games: To download favorite games.

Ø Movie Schedules: To view movie schedules and to book tickets in a theatre.

Ø Applications: Different applications, AP Telephone Directory being one of them.

Ø Hutch Privileges: Information on different privileges HUTCH is providing to its users.

This page once visited writes the accessed mobile number into the Wap Access table. Using Server variable “MSISDN” value can get the mobile number.

Telugu World:

www.aponmobile.com/wap/telugu/telugucate.aspx

This page contains three sub links:

Panchangam Bay Names Telugu World

Panchangam Page:

www.aponmobile.com/wap/telugu/panchangam.aspx

This page once visited gives the panchangam the Telugu astrological information of the current day.

Baby Names Page:

www.aponmobile.com/wap/telugu/babynames.wml

Baby Name Results Page:

www.aponmobile.com/wap/telugu/babynames.aspx

Telugu World

www.aponmobile.com/wap/telugu/teluguworld.aspx

This page is meant to help people learn Telugu terminologies and other info relates to Telugu like Ruthuvulu (Telugu Seasons) etc. Once a user clicks a link in this he goes to the description page.

Telugu World Description Page:

www.aponmobile.com/wap/telugu/teluguworlddetails.aspx

In this the description related to the link clicked in the Telugu world is shown.

Applications Page:

www.aponmobile.com/wap/applications/application.aspx

In this page we can see other applications list with Telephone Directory Link.

Directory Welcome Page:

www.aponmobile.com/wap/applications/applicationwelcome.aspx

Directory Main Page

www.aponmobile.com/wap/applications/directory/main.aspx

In this a list of Districts in AP are shown. Here you have to select an appropriate district, which takes us to the search option page.

Search Option Page

www.aponmobile.com/wap/applications/directory/Searchoption.aspx

In this option is given to search whether by number or Name. On clicking Next it takes us to Search Screen.

Search Page

www.aponmobile.com/wap/applications/directory/Search.aspx

Directory Result Page

www.aponmobile.com/wap/applications/directory/Directory.aspx

If exact Name or number is found u will get the result. Otherwise appropriate message is given. U can see both types of searches done in the screens both by name and number.

History

How does it work?

What is WAP?

The wireless industry came up with the idea of WAP. The point of this standard was to show Internet contents on wireless clients, like mobile phones.

WAP stands for Wireless Application Protocol
WAP is an application communication protocol
WAP is used to access services and information
WAP is for handheld devices such as mobile phones
WAP is a protocol designed for micro browsers
WAP enables the creating of web applications for mobile devices.
WAP uses the mark-up language WML (not HTML)
WML is defined as an XML 1.0 application
The Wireless Application Protocol

WAP Micro Browsers

What is WML?

WAP Homepages

WML Tags

WML Decks and Cards

The Wireless Markup Language (WML)

Introduction

http://www.wapforum.org/DTD/wml_1.1.xml

A valid WML document must correspond to this DTD or it cannot be processed.

Understanding the Wireless Markup Language

http://www.wapforum.org/DTD/wml_1.1.xml

Following the prolog, every XML document contains a single element that contains all other sub elements and entities. Like HTML all elements are bracketed by the

and

characters.

As an example: datadatadata. There can only be one document element per document. With WML, the document element is ; all other elements are contained within it.

Please select your user name.

In the code above, the card element contains the id and title attributes. (On a side note, a comment in WML must appear between the tags

Valid WML Elements

WML predefines a set of elements that can be combined together to create a WML document. These elements include can be broken down into two groups: the Deck/Card elements and the Event elements.

Deck/Card Elements

wml

card

template

head

access

Don’t have Stress At Computer

sailjamehra — Tue, 01 Mar 2011 05:50:08 +0000

Don’t have Stress At Computer Why Because, Brain has

Consciousness
Scientific perspective
Philosophers’ perspective
Emergence of consciousness
Evolution and consciousness
Our approach for machine consciousness
Consciousness: functional requirements
Definition of machine consciousness
Computational model
Computational model: implications

Description of Consciousness

The quality or state of being aware especially of something within oneself .
Nobody has a slightest idea of how anything material can be conscious .
…our subjective experience or conscious state involving awareness, attention, and self reference.
Anything that we are aware of at a given moment forms part of our consciousness, making conscious experience at once the most familiar and most mysterious aspect of our lives.

Scientific perspective

It may be pointless trying to define consciousness, its evolution or function as they may have many different interpretations, similar to other big words like perception, learning, knowledge, attention, etc .
Consciousness refers to focusing attention, mental rehearsal, thinking, decision making, awareness, alerted state of mind, voluntary actions and subliminal priming, concept of self and internal talk .
Consciousness is a combination of self awareness and qualia and memory plays an important role in it .
Consciousness is a dynamic process and it changes with development of brain. Further, at macro-level there is no consciousness centre and at micro-level there are no committed neurons or genes dedicated to consciousness .

Philosophers’ perspective

Phenomenally conscious states are those states that possess fine-grained intentional contents of which the subject is aware, being the target or potential target of some sort of higher-order representation.
Consciousness is accomplished by a distributed society of specialists that is equipped with working memory, called a global workspace, whose contents can be broadcast to the system as a whole .
…various events of content-fixation occurring in various places at various times in the brain … there is no single place in brain for consciousness .

Nisargadatta states that awareness is not a part (subset) of consciousness but instead it is its superset

– appearance and evolution of consciousness
- Human Beings
- Fully developed cross-modal representation
- Sensory capabilities: auditory, taste, touch, vision, etc.
- Bi-frontal cortex: planning, thought, motivation
- Impossible at present
- Hedgehog (earliest mammals)
- Cross-modal representation
- Sensory capabilities: auditory, touch, vision (less developed), etc.
- Small frontal cortex
- Impossible at present
- Birds
- Primitive cross-modal representation
- Sensory capabilities: auditory, touch, vision, olfactory.
- Primitive associative memory
- Associative memories
- Evolution and consciousness
  –absence of consciousness
- To avoid Our approach consciousness
- Define consciousness in functional terms
- Identify minimum functional requirements
- Identify minimum functional blocks, their individual roles, their inter-relationship
- A computational model
- Consciousness: functional requirements
- Intelligence
  - - Mechanism to acquire and represent Knowledge
    - Knowledge is a result of learning
- Attention and attention Switching
- Cognitive perception and related action
  - - Semantic memory
    - Associative sensory-motor memory
    - Episodic memory – not necessary
- Cognitive awareness
- Central executive
- Not necessary alive
- Consciousness requires
- Intelligence (ability)
- Awareness (state)
- Embodied Intelligence
- Definition
  - Embodied Intelligence (EI) is a mechanism that learns how to minimize hostility of its environment
    - Mechanism: biological, mechanical or virtual agent
- with embodied sensors and actuators
  - - EI acts on environment and perceives its actions
    - Environment hostility is persistent and stimulates EI to act
    - Hostility: direct aggression, pain, scarce resources, etc
    - EI learns so it must have associative self-organizing memory
    - Knowledge is acquired by EI
- Motivated Learning
- Definition: Motivated learning (ML) is pain based motivation, goal creation and learning in embodied agent.
- - - Various pains and external signals compete for attention.
    - Attention switching results from competition.
    - Cognitive perception is aided by winner of competition.
- Attention
- Selective process of
  - - cognitive perception/action
    - other cognitive experiences like
      - thoughts, action planning, expectations, dreams
- Result of attention switching
  - - needed to have cognitive experience
    - leads to a sequence of cognitive experiences
- Attention Switching !!!
- Dynamic process resulting from competition between
  - - representations related to motivations
    - sensory inputs
    - internal thoughts including spurious signals (like noise).
- May be a result of
  - - deliberate cognitive experience (and thus fully conscious signal)
    - subconscious process (stimulated by internal or external signals)
- Thus, while paying attention is a conscious experience, switching attention does not have to be.
- Central Executive
- Central executive, by relating cognitive experience to internal motivations and plans, creates self-awareness and conscious state of mind.
- Computational Model of Machine Consciousness
- Central Executive
- Tasks
  - - cognitive perception
    - attention
    - attention switching
    - motivation
    - goal creation and selection
    - thoughts
    - planning
    - learning, etc.
- Requires
  - - capability to dynamically select and directly execute programs
    - capability to activate semantic memory and control emotions

Living Being
Evolutionary traits	Analogous feasibility in machines

Living Being		Evolutionary traits	Analogous feasibility in machines
	Human Beings	Fully developed cross-modal representation Sensory capabilities: auditory, taste, touch, vision, etc. Bi-frontal cortex: planning, thought, motivation	Impossible at present
	Hedgehog (earliest mammals)	Cross-modal representation Sensory capabilities: auditory, touch, vision (less developed), etc. Small frontal cortex	Impossible at present
	Birds	Primitive cross-modal representation Sensory capabilities: auditory, touch, vision, olfactory. Primitive associative memory	Associative memories

Philosophers’ perspective

Phenomenally conscious states are those states that possess fine-grained intentional contents of which the subject is aware, being the target or potential target of some sort of higher-order representation.
Consciousness is accomplished by a distributed society of specialists that is equipped with working memory, called a global workspace, whose contents can be broadcast to the system as a whole .
…various events of content-fixation occurring in various places at various times in the brain … there is no single place in brain for consciousness .

Nisargadatta states that awareness is not a part (subset) of consciousness but instead it is its superset

Emergence of Consciousness

Evolution and consciousness
– appearance and evolution of consciousness

Computational Model: Implications

The motivations for actions are physically distributed
- - competing signals are generated in various parts of machine’s mind
Before a winner is selected, machine does not interpret the meaning of competing signals
Cognitive processing is predominantly sequential
- - winner of the internal competition serves as an instantaneous director of the cognitive thought process, before it is replaced by another winner
Top down activation for perception, planning, internal thought or motor functions
- - results in conscious experience
    - - decision of what is observed
      - planning how to respond
  - a continuous train of such experiences constitutes consciousness

so set Goal like :

Embodied Intelligence

Definition
- Embodied Intelligence (EI) is a mechanism that learns how to minimize hostility of its environment
  - Mechanism: biological, mechanical or virtual agent

with embodied sensors and actuators
- - EI acts on environment and perceives its actions
  - Environment hostility is persistent and stimulates EI to act
  - Hostility: direct aggression, pain, scarce resources, etc
  - EI learns so it must have associative self-organizing memory
  - Knowledge is acquired by EI

Motivated Learning

Definition: Motivated learning (ML) is pain based motivation, goal creation and learning in embodied agent.

- - Various pains and external signals compete for attention.
  - Attention switching results from competition.
  - Cognitive perception is aided by winner of competition.

Attention

Selective process of
- - cognitive perception/action
  - other cognitive experiences like
    - thoughts, action planning, expectations, dreams
Result of attention switching
- - needed to have cognitive experience
  - leads to a sequence of cognitive experiences

Attention Switching !!!

Dynamic process resulting from competition between
- - representations related to motivations
  - sensory inputs
  - internal thoughts including spurious signals (like noise).
May be a result of
- - deliberate cognitive experience (and thus fully conscious signal)
  - subconscious process (stimulated by internal or external signals)

Thus, while paying attention is a conscious experience, switching attention does not have to be.

Central Executive

Central executive, by relating cognitive experience to internal motivations and plans, creates self-awareness and conscious state of mind.

Computational Model of Machine Consciousness

Central Executive

Tasks
- - cognitive perception
  - attention
  - attention switching
  - motivation
  - goal creation and selection
  - thoughts
  - planning
  - learning, etc.

Requires
- - capability to dynamically select and directly execute programs
  - capability to activate semantic memory and control emotions

Computational Model: Implications

The motivations for actions are physically distributed
- - competing signals are generated in various parts of machine’s mind
Before a winner is selected, machine does not interpret the meaning of competing signals
Cognitive processing is predominantly sequential
- - winner of the internal competition serves as an instantaneous director of the cognitive thought process, before it is replaced by another winner
Top down activation for perception, planning, internal thought or motor functions
- - results in conscious experience
    - - decision of what is observed
      - planning how to respond
  - a continuous train of such experiences constitutes consciousness

so set Goal like :

Reinforcement Learning

Single value function
Measurable rewards
- Can be optimized
Predictable
Objectives set by designer
Maximizes the reward
- Potentially unstable
Learning effort increases with complexity
Always active

Motivated Learning

Multiple value functions
- One for each goal
Internal rewards
- Cannot be optimized
Unpredictable
Sets its own objectives
Solves minimax problem
- Always stable
Learns better in complex environment than RL
Acts when needed

finally reach goal like this…:

Filed under: Don’t have Stress At Computer

Cells and Organelles_The Cell Membrane

sailjamehra — Thu, 25 Mar 2010 13:36:37 +0000

Do all membranes have the same basic structure?

•Both the cell surface membrane and the membranes surrounding certain organelles have the same basic structure. Much of the membrane is made up of a ‘sea’ of phospholipids with protein molecules ‘floating’ in between the phospholipids.

•What is an intrinsic protein? •What is an extrinsic protein? •Why is it called the fluid mosaic model?

•Allow movement of substances, such as glucose, across the membrane •NO ATP REQUIRED

•Actively transport substances, such as minerals, across the membrane •ATP is REQUIRED

(a) Channel VS (b) Carrier

Proteins

•What is the bilayer? •The phosphate heads are polar molecules and so are water-soluble. •The lipid tails are non-polar and therefore are not water-soluble.

•The phosphate heads are polar. Are they water-soluble? •The lipid tails are non-polar. Are they water-soluble?

Filed under: science

Java Naming and Directory

sailjamehra — Tue, 02 Mar 2010 05:16:15 +0000

Java Naming and Directory
Interface (JNDI)

•What is JNDI?

•Naming and Directory Services

•Naming Concepts •Issues

•JNDI Architecture

•Programming with JNDI

•Role of JNDI in J2EE

•Class.forName(“com.microsoft.jdbc.

sqlserver.SQLServerDriver”);

•cnn = DriverManager.getConnection

(“jdbc:microsoft:sqlserver://meher:1433″,“username”,“password”);

•Context ctx = new InitialContext();

•DataSource ds =

(DataSource)ctx.lookup(“myname”);

•Connection con = ds.getConnection(“abc”,”***”);

JNDI

Java Naming and Directory Interface (JNDI) provides a standard interface for Java applications to access naming and directory services.

Naming Service

• Naming Service performs:

– Binding: Associating names with objects

– Lookup: Find an object based on a name.

• Examples: DNS and File systems

• Examples:

– DNS

– Filesystems

Directory Service

•Directory is a naming service that stores

objects with attributes.

– Usernames and passwords etc stored in attrs.

•Tree like structure

Names

•Atomic name is a indivisible component of a

name

– in /etc/fstab, etc and fstab are atomic names.

•Compound name is zero or more atomic

names put together.

– /etc/fstab is a compound name

Binding

•Binding is an association of a name with an object.

– Filename “autoexec.bat” has a binding to some file data on the disk.

– “c:\windows” foldername is bound to a folder on your drive.

•Compound name such as /usr/people/ed/.cshrc

consists of multiple bindings, one to usr, one to

people, one to ed, and one to .cshrc.

Context

•Contains zero or more bindings.

– Each binding has a distinct atomic name.

•/etc contains files named mtab and exports.

•The /etc folder is a context containing bindings with atomic names mtab and exports.

•mtab and exports are each bound to a file on

the disk.

Sub-Context

•/usr – CONTEXT

– /usr/people – SUB-CONTEXT

– /usr/bin – SUB-CONTEXT

– /usr/local – SUB-CONTEXT

•Each atomic name is bound to a sub-context the subfolder.

•Subcontext are full-fledged contexts

•Can contain more name-object bindings, such as other files or other folders.

Naming System and Namespaces

•Naming system: A connected set of

contexts.

•Namespace: all the names contained within

that naming system.

InitialContext

•Starting point for exploring a namespace.

•Starting point for performing all naming and

directory operations.

Issues

•Many naming and directory products.

– Netscape Directory Server

– MicrosoftActiveDirectory

•Various naming and directory protocols: Each

directory standard has a different protocol for

accessing the directory.

– Lightweight Directory Access Protocol (LDAP)

– Network Information System (NIS)

– Novell’s Network Directory System (NDS)

•EveryDS has it’s ownAPI.

Introducing JNDI

•Standard interface to interact with naming and

directory systems.

•For Java programs.

•Provides common interface to disparate

directories: Same API for LDAP and NIS NDS.

•Used in EJB, RMI-IIOP, JDBC for operations like

locating entities i.e. Users, Machines (e.g. printer),

Objects, Services (e.g. datasource) etc.

JNDI Packages

The JNDI comprises of 5 packages

•javax.naming – Contains classes and interfaces for accessing naming services

•javax.naming.directory – Extends javax.naming and provides functionality to access directory services in addition to naming services

•javax.naming.event – Classes and interfaces for supporting event notification in naming and directory services

•javax.naming.ldap – Classes and interfaces for using features that are specific to LDAP v3 that are not already covered by the more generic javax.naming.directory

•javax.naming.spi – Vendors develop their naming/directory services conforming to SPI. Applications can then access these services through the JNDI API

InitialContextFactory

•Used to acquire an initial context

•Implementation of the JNDI driver: Knows the

specific semantics of a particular directory

structure.

•bootstrapping.

•Necessary information for JNDI to acquire that

initial context.

– The IP address of the J2EE server

– The port number that the J2EE server accepts

– Any username/password necessary to use the J2EE server.

javax.naming.Context ctx =

new javax.naming.InitialContext

(System.getProperties());

java

-Djava.naming.factory.initial=

com.sun.jndi.fscontext.RefFSContextFactory

-Djava.naming.provider.url=

file:c:\examples.InitCtx

class of the JNDI driver

•provider URL: URL that the service provider

accepts for bootstrapping.

Other JNDI operations

Methods invoked on a Context

•list() – list of contents available at the context.

– names of objects bound to the JNDI tree

– subcontexts.

•lookup() – look up objects bound to the JNDI tree

– Return type is driver specific

• RMI-IIOP java.rmi.Remote

• file system java.io.File

•rename() – give a new name to a context

– c:\temp to c:\tmp

•createSubcontext() – create a subcontext at the

context

– c:\foo\bar at the folder c:\foo.

•destroySubcontext() – destroy a subcontext of the

context

– Destroy c:\foo\bar from the folder c:\foo.

•bind() – associates a name to a content and stores

it at the Context

– JNDI drivers accept different parameters to bind()

•rebind() – forces a bind even if some object is

already bound to the name.

Binding

import javax.naming.*;

public class Startup {

public static void main(String args[]) throws Exception {

AccountImpl acct_impl = new AccountImpl();

Context ctx = new InitialContext (System.getProperties());

ctx.rebind(“myname”, acct_impl);

}

Looking Up

import javax.naming.*;

import java.rmi.*;

public class Client {

public static void main (String[] args) throws Exception { Context ctx = new InitialContext (System.getProperties());

Object remoteObject = ctx.lookup(“myname”);

Account account = (Account)

javax.rmi.PortableRemoteObject.narrow (

remoteObject, Account.class);

int b = account.method1(5));}}

Role of JNDI in J2EE

•J2EE servers have a JNDI implementation.

•Used to Look up beans.

•Connect to resource factories

– JDBC DataSource

– Java Message Service (JMS) drivers

•Acquiring a reference to the Java

Transaction API’s (JTA) UserTransaction

interface.

Filed under: Java Naming and Directory

CORBA – part2

sailjamehra — Mon, 22 Feb 2010 13:49:08 +0000

IDL Modules

Map to Java packages

Unfortunately, it has the root level name of the module

Clutters up your package hierarchy

e.g. module Calc ->

package Calc

interface Calc.Adder

not package ORG.omg.CORBA.modules.Calc

IDL Interfaces

Map to Java interfaces

IDL Operations

Map to Java methods

IDL Attributes

Map to pair of functions

IDL

string name;

Java

public void name(String val);

public String name();

Yes, it looks stupid. Sorry.

Idltojava

Development tool

Automatically generates java stubs, skeletons, helpers, holders, …

Generates stubs for specific remote interfaces

Stubs

Java objects call stub methods

Stubs communicate with CORBA objects

and vice versa

Transparent integration

Skeletons

ORB passes request to skeleton (like a stub)

Skeleton calls local implementation

Remote Interfaces and Stubs

idltojava input

Calc.idl

module Calc {

interface Adder {

long add(in long x, in long y);

}

idltojava output

idltojava Calc.idl

Adder.java (a Java interface that maps the IDL interface)
_AdderStub.java (a client stub)
_AdderImplBase.java (a server skeleton)
AdderHelper.java (a helper class)
AdderHolder.java (a holder class)

Must compile these files and put them in your CLASSPATH

Adder.java

u Created for you by idltojava

package Calc;

public interface Adder

extends org.omg.CORBA.Object {

int add(int x, int y);

}

Implementing a server

Extend base class

Implement all methods declared in IDL

Provide a main method

Create an ORB instance

Create a server instance

Inform the ORB about the instance

Acquire a Naming Context

Register the instance in that Naming Context under some name

AdderServer.java

class AdderServer extends _AdderImplBase

{

public int add( int x, int y ) {

System.out.println(x + ” + ” + y + ” = ” + (x+y));

return x + y;
}

public static void main(String args[]) {

// create and initialize the ORB

ORB orb = ORB.init(args, null);

// create server and register it with the ORB

AdderServer adderRef = new AdderServer();

orb.connect(adderRef);

// get the root naming context

org.omg.CORBA.Object objRef =

orb.resolve_initial_references(“NameService”);

NamingContext ncRef = NamingContextHelper.narrow(objRef);

// bind the Object Reference in Naming

NameComponent nc = new NameComponent(“Adder”, “”);

NameComponent path[] = {nc};

ncRef.rebind(path, adderRef);

Implementing a client

Create an ORB

Get a reference to the Naming Context

Look up the correct name in that Naming Context

Receive an object reference to that object

Actually, to its Stub

Invoke methods on the reference

Object Reference

Two Meanings

1. An abstract concept referring to a specific object living on a specific host, attached to a specific ORB

2. A local Java reference to an object that relays messages to that object

Obtained from

new keyword

a Factory Object

the Naming Service

Naming Service

tnameserv

t is for “transient”

Maps name to object reference

An implementation of the CORBA Object Service (COS) name service

to run the Naming Service

UNIX: tnameserv &

Win32: start /m tnameserv

Fire it up

start /m tnameserv

start java AdderServer

java AdderClient

2 + 2 = ?

Pseudo-objects

The ORB is a pseudo-object

It works just like a remote object, only it’s local

The Basic Object Adapter (BOA)

Another pseudo-object

Helps register objects with the ORB

Functions

Maintain Implementation Repository

Generate and interpret object references

Activate and deactivate implementation objects

Invoke methods via skeletons

Why do you need both an ORB and a BOA?

I’m not really sure

Allows vendors to optimize or enhance functionality

cache object state elsewhere

E.g. Object database

Using the BOA

Slightly different procedure for initializing objects

Hides name service from you

Ask the BOA to register the object

Ask the Helper object to bind the object

Once the object is created, interface is identical

Just call methods using normal Java syntax

BOA Object Activation

Shared server

Multiple objects, one server

Normal procedure

Multithreaded (handled by CORBA implementation)

Unshared server

New process for each object

Server-per-method

Batch processing

Persistent server

Shared server, but object not created by ORB

BOA Object Activation Scenario

Server creates object instance

obj = new MyObject();

Server registers object with BOA

boa.create(interface_name, implementation_name, reference_data)

VisiBroker does this for you in superclass constructor

Server tells BOA the object is ready

boa.obj_is_ready(obj)

Server tells BOA that all objects are ready

boa.impl_is_ready()

Objects shut down

boa.deactivate_obj(this)

Server shuts down

boa.deactivate_impl()

Threads in JavaIDL

Remote invocations happen on a separate thread

Must make sure your remote objects are thread-safe

Callbacks

Pass in a reference to some CORBA object

The server object can invoke methods on that reference

ORB automatically generates a stub on the server side

The server has become the client, and vice versa

Obtaining Object References

From the ORB

orb.resolve_initial_references(“NameService”)

From a Naming Context

From a Stringified reference

From another object

From a parameter to your remote method

Helper Objects

How CORBA does casting

narrow method changes the type of an object reference

// get the root naming context

org.omg.CORBA.Object objRef =

orb.resolve_initial_references(“NameService”);

NamingContext ncRef = NamingContextHelper.narrow(objRef);

Naming Contexts

Directory structure for CORBA

Naming Component = file

Naming Context = directory

Can add a Context as a Component

like subdirectories

Can add a Context on a different name server

like symbolic links

Stringification

Stringified reference is ORB-independent

Object to string

org.omg.CORBA.Object obj = …

String str = orb.object_to_string(obj);

String to object

org.omg.CORBA.Object obj = orb.string_to_object(str);

Visigenic: Caffeine

Java to IDL compiler

Symantec: Visual Café 3.0 Enterprise Suite

Java to IDL compiler

Automatic client adapter bean generation

Makes a JavaBean that’s a proxy to a CORBA object

Distributed debugging

Follow call chain, examine variables, et al.

Across many VMs, many hosts, many OSs

Publish-Subscribe System

Channel: an avenue for real-time data exchange

Consumers can subscribe to arbitrary data channels

Producers can publish data on channels

Invokes callback method on consumer

Object Model

PSServer

Channel getChannel(String channelName)

creates channel if it doesn’t already exist

Channel

void subscribe(Subscriber sub)

void publish(Object data)

Subscriber

void dataArrived(Object data)

Dynamic Invocation Interface (DII)

CORBA is fully self-aware

Methods for acquiring

List of all services

List of known objects

Interfaces of known objects

Etc.

Well-documented elsewhere

Interface Repositories

JavaIDL clients do not typically need or use an Interface Repository

All of the needed type information is available in the stubs or is resolved by an object’s server

JavaIDL supports access to Interface Repository information made available by other CORBA object implementations.

Implementation Repository

contains information that allows the ORB to locate and activate implementations of objects

also store additional information associated with implementations of ORB objects.

Debugging information

Administrative control

Resource allocation

Security

Value Objects

CORBA 3.0

Blobs

Avoids network latency of pass-by-reference objects

RMI over IIOP

In Development

Uses IIOP as transport protocol

Uses Value Objects to pass Java serialized objects

CORBA via RMI

Possible using middleware server

RMI from client to middleware

IIOP from middleware to other servers

Can use Servlet as middleware

CORBA and EJB

Transport

EJB uses RMI interface, RMI uses IIOP

CORBA 3.0 promises object compatibility with EJB

Not quite sure what that means

Some EJB Servers contain an ORB

All EJB Objects are also CORBA objects

All EJB Servers use CORBA Transactions (via JTS)

That means that any client can make a distributed transaction that includes both CORBA and EJB Objects

Not an either-or decision

You can have both EJB and CORBA working together in a single system

Java Transactions

Java Transaction Service (JTS)

A standard Java mapping of the OMG Object Transaction Service (OTS)

packages org.omg.CosTransaction and org.omg.CosTSPortability

Java Transaction API (JTA)

High-level transaction management specification

package javax.transaction

class UserTransaction

Object Transaction Service (OTS)

Distributed transaction specification

Part of CORBA, but also standalone

Transactions can span

multiple queries

multiple objects

multiple servers

multiple databases

multiple vendors’ products

OTS Features

Distributed transactions

Flat or nested transactions

Two-phase commit

Vendor interoperability (?)

Filed under: corba java part-2

CORBA – PART1

sailjamehra — Wed, 17 Feb 2010 14:00:18 +0000

CORBA and Java

Abstract

CORBA loves Java! CORBA provides a platform-independent, language-independent way to write applications that can invoke objects that live across the room or across the planet. Java is an object-oriented language that’s ideal for writing the clients and servers living on the Object Bus. In this session, we examine the ways they interoperate programmatically, as we walk you step-by-step from a CORBA IDL, to a server and client both written in Java, running on top of a 100%-Java ORB. We also discuss the relationship between CORBA and RMI, and discuss some of the real-world issues involved in deploying a CORBA-based application. Recommended: some knowledge of CORBA, ability to read Java source code.

What is CORBA?

Common Object Request Broker Architecture

Communication infrastructure for distributed objects

Allows a heterogeneous, distributed collection of objects to collaborate transparently.

What is CORBA good for?

Developing distributed applications

Locating remote objects on a network

Sending messages to those objects

Common interface for transactions, security, etc.

CORBA Services (more later)

Why Distributed Applications?

Data is distributed

Administrative and ownership reasons

Heterogeneous systems

Shared by multiple applications

Scalability

Computation is distributed

Scalability: multiprocessing

Take computation to data

Heterogeneous architectures

Users are distributed

Multiple users interacting and communicating via distributed applications

Distributed Object Systems

All entities are modeled as objects

Systems support location transparency

Interfaces, not implementations, define objects

Good distributed object systems are open, federated systems

What is the OMG?

Designers of CORBA

Consortium of 700+ companies

Not including Microsoft

Members:

platform vendors

database vendors

software tool developers

corporate developers

software application vendors

It’s Just A Spec

Has never been fully implemented

Probably never will be

Industry moves quickly and spec has to keep up

Interoperability vs. portability

Pass-by-value

Basic CORBA Architecture

CORBA Objects

Examples

Service

Client

Component

Business object

CORBA objects approach universal accessibility

Any Language

Any Host on network

Any Platform

CORBA Elements

1. ORB

2. CORBA Services

3. CORBA Facilities

4. Application Objects

ORB

Object Request Broker

“Object Bus”

Handles all communication among objects

Each host (machine) has its own ORB

ORBs know how to talk to each other

ORB also provides basic services to client

ORB Responsibilities

Find the object implementation for the request

Prepare the object implementation to receive the request

Communicate the data making up the request

Retrieve results of request

Network of ORBs

There’s an ORB on the server too

ORB receives request

IIOP

Internet Inter-Orb Protocol

Network or “wire” protocol

Works across TCP/IP (the Internet protocol)

ORB Features

Method invocations

Static and Dynamic

Remote objects or CORBA services

High-level language bindings

Use your favorite language; ORB translates

Self-describing

Provides metadata for all objects and services

Local or remote

Same API wherever target object lives

Preserves context

Distributed security and transactions

Coexistence with legacy code

Just provide a wrapper object

What is an ORB really?

Not a separate process

Library code that executes in-process

Listens to TCP ports for connections

One port per local object

Opens TCP sockets to other objects

N ports per remote machine

IDL

Interface Definition Language

Defines protocol to access objects

Like a contract

Well-specified

Language-independent

IDL Example

module Calc {

interface Adder {

long add(in long x, in long y);

}

Defines an object called Adder with a method called add

Stubs and Skeletons

Stub

lives on client

pretends to be remote object

Skeleton

lives on server

receives requests from stub

talks to true remote object

delivers response to stub

Stubs and Skeletons (Fig.)

Client vs. Server

in CORBA, a client is a client relative to a particular object

i.e. an object with a reference to a “server” object

A client may also act as a server

If it has an IDL and stubs and skeletons

Technically, a CORBA server contains one or more CORBA objects

Different Meanings of “Server”

Host machine

Program running on host machine

CORBA object running inside program

has IDL, stub, skeleton

Sometimes called a Servant

Stubs and Skeletons -> Platform Independence

Client code has no knowledge of the implementation of the object or which ORB is used to access the implementation.

CORBA Services

APIs for low-level, common tasks

Life Cycle Service

creating, copying, moving, removing objects

Naming Service

Register objects with a name

Look up objects by name

CORBA Services

Concurrency Control Service

Obtain and release exclusive locks

Transaction Service

Two-phase commit coordination

Supports nested transactions

Persistence Service

Storing objects in a variety of databases

RDBMS, OODBMS, file systems

Security Service

Authentication, ACLs, encryption, etc.

Event Service

Uncoupled notifications

Relationship

Externalization

Query

Licensing

Properties

Time

Trader

Collection

… and so on…

See what I mean about it never being implemented?

Frameworks for specialized applications

Distributed Document Component Facility

OpenDoc

In progress:

Agents

Business Objects

Internationalization

N-Tier Design with CORBA

Three Tiers

User Interface Tier

Business Logic Tier

Data Storage Tier

Can use CORBA objects in each tier

Part II: Java IDL – Using CORBA from Java

Should be named “Java CORBA”

More than just IDL

Full (?) implementation of CORBA in 100% Java

Three Parts

ORB

Naming Service

idltojava compiler

Ships with JDK 1.2

Java CORBA Products

The Java 2 ORB

VisiBroker for Java

OrbixWeb

Netscape Communicator

Various free or shareware ORBs

Transparent API

JavaIDL turns IDL into direct method calls

Easy to program

Clients have no knowledge of implementation

Highly portable

The Java ORB

100% Java

Generic

Allows Java IDL applications to run either as stand-alone Java applications, or as applets within Java-enabled browsers

Uses IIOP

Visigenic (Inprise) VisiBroker

Netscape Communicator

Oracle Web Server 3.0

Free download

Iona OrbixWeb

IDL to Java Mapping

Defined by OMG

Translates IDL concepts into Java language constructs

Everything is accessible by writing normal-looking Java code

IDL to Java Type Mapping

Filed under: CORBA WITH JAVA

FTP – commands

sailjamehra — Wed, 17 Feb 2010 13:50:57 +0000

FTP Commands Overview

Command Short Description Command Short Description

! Run mdir Multiple directory listing

? Help mget Mulitiple get

append Append to a file mkdir Make directory

ascii Set ASCII transfer type mls Multiple listing

bell Toggle bell mput Multiple Put

binary Set binary trasfer type open Connect to FTP server

bye Terminate ftp session and exit prompt Toggle prompting

cd Change directory put Upload file

close Terminiate FTP session pwd Present working directory

debug Toggle debugging mode quit Terminate FTP session and quit

delete Delete file quote Send arbitrary FTP command

dir Directory listing recv Receive file

disconnect Terminate FTP session remotehelp Help from remote server

get Download file rename Rename file

glob Toggle glob rmdir Remove directory

hash Toggle hash # send Send one file

help Local help status Current status

lcd Change local directory trace Toggle packet tracing

literal Send arbitrary FTP command type Show file transfer type

ls List contects of remote directory user Connect as new user

mdelete Delete multiple files verbose Toggles verbose mode

!

Escapes to the shell (command prompt) to run the specified command on the local computer.
     ! command

Parameter

command – Specifies the command to run on the local computer. If command is omitted, the local command prompt is displayed; type exit to return to ftp.

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?

Displays descriptions for ftp commands. ? is identical to help.
     ? [command]

Parameter

command – Specifies the name of the command about which you want a description. If command is not specified, ftp displays a list of all commands.

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append

Appends a local file to a file on the remote computer using the current file type setting.
     append local-file [remote-file]

Parameters

local-file – Specifies the local file to add.

remote-file – Specifies the file on the remote computer to which local-file will be added. If remote-file is omitted, the local filename is used for the remote filename.

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ascii

Sets the file transfer type to ASCII, the default.
     ascii

Note

FTP supports two file transfer types, ASCII and binary image. ASCII should be used when transferring text files. See also binary.

In ASCII mode, character conversions to and from the network standard character set are performed. For example, end-of-line characters are converted as necessary, based on the target operating system.

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bell

Toggles a bell to ring after each file transfer command is completed. By default, the bell is off.
     bell
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binary

Sets the file transfer type to binary.
     binary

Note

FTP supports two file transfer types, ASCII and binary image. Binary should be used when transferring executable files. In binary mode, the file is moved byte-by-byte. See also ascii.

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bye

Ends the FTP session with the remote computer and exits ftp.
     bye
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cd

Changes the working directory on the remote computer.
     cd remote-directory

Parameter

remote-directory – Specifies the directory on the remote computer to change to.

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close

Ends the FTP session with the remote server and returns to the command interpreter.
     close
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debug

Toggles debugging. When debugging is on, each command sent to the remote computer is printed, preceded by the string —>. By default, debugging is off.
     debug
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delete

Deletes files on remote computers.
     delete remote-file

Parameter

remote-file - Specifies the file to delete.

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dir

Displays a list of a remote directory’s files and subdirectories.
     dir [remote-directory] [local-file]

Parameters

remote-directory – Specifies the directory for which you want to see a listing. If no directory is specified, the current working directory on the remote computer is used.

local-file – Specifies a local file to store the listing. If not specified, output is displayed on the screen.

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disconnect

Disconnects from the remote computer, retaining the ftp prompt.
     disconnect
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get

Copies a remote file to the local computer using the current file transfer type.
     get remote-file [local-file]

Parameters

remote-file – Specifies the remote file to copy.

local-file – Specifies the name to use on the local computer. If not specified, the file is given the remote-file name.

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glob

Toggles filename globbing. Globbing permits use of wildcard characters in local file or path names. By default, globbing is on.
     glob
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hash

Toggles hash-sign (#) printing for each data block transferred. The size of a data block is 2048 bytes. By default, hash mark printing is off.
     hash
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help

Displays descriptions for ftp commands.
     help [command]

Parameter

command – Specifies the name of the command about which you want a description. If command is not specified, ftp displays a list of all commands.

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lcd

Changes the working directory on the local computer. By default, the working directory is the directory in which ftp was started.
     lcd [directory]

Parameter

directory – Specifies the directory on the local computer to change to. If directory is not specified, the current working directory on the local computer is displayed.

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literal

Sends arguments, verbatim, to the remote FTP server. A single FTP reply code is expected in return.
     literal argument [ ...]

Parameter

argument – Specifies the argument to send to the FTP server.

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ls

Displays an abbreviated list of a remote directory’s files and subdirectories.
     ls [remote-directory] [local-file]

Parameters

remote-directory – Specifies the directory for which you want to see a listing. If no directory is specified, the current working directory on the remote computer is used.

local-file – Specifies a local file to store the listing. If not specified, output is displayed on the screen.

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mdelete

Deletes files on remote computers.
     mdelete remote-files [ ...]

Parameter

remote-files – Specifies the remote files to delete.

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mdir

Displays a list of a remote directory’s files and subdirectories. Mdir allows you to specify multiple files.
     mdir remote-files [ ...] local-file

Parameters

remote-files – Specifies the directory for which you want to see a listing. Remote-files must be specified; type “-” (no quotes) to use the current working directory on the remote computer.

local-file – Specifies a local file to store the listing. Type “-” (no quotes) to display the listing on the screen.

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mget

Copies remote files to the local computer using the current file transfer type.
     mget remote-files [ ...]

Parameter

remote-files – Specifies the remote files to copy to the local computer.

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mkdir

Creates a remote directory.
     mkdir directory

Parameter

directory – Specifies the name of the new remote directory.

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mls

Displays an abbreviated list of a remote directory’s files and subdirectories.
     mls remote-files [ ...] local-file

Parameters

remote-files – Specifies the files for which you want to see a listing. Remote-files must be specified; type – to use the current working directory on the remote computer.

local-file – Specifies a local file to store the listing. Type – to display the listing on the screen.

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mput

Copies local files to the remote computer using the current file transfer type.
     mput local-files [ ...]

Parameter

local-files – Specifies the local files to copy to the remote computer.

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open

Connects to the specified FTP server.
     open computer [port]

Parameters

computer – Specifies the remote computer to connect to. Computer can be specified by IP address or computer name (a DNS or HOSTS file must be available). If auto-login is on (default), FTP also attempts to automatically log the user in to the FTP server (see Ftp to disable auto-login).

port – Specifies a port number to use to contact an FTP server.

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prompt

Toggles prompting to force interactive prompting on multiple commands. Ftp prompts during multiple file transfers to allow you to selectively retrieve or store files; mget and mput transfer all files if prompting is turned off. By default, prompting is on.
     prompt
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put

Copies a local file to the remote computer using the current file transfer type.      put local-file [remote-file]

Parameters

local-file – Specifies the local file to copy.

remote-file – Specifies the name to use on the remote computer. If not specified, the file is given the local-file name.

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pwd

Displays the current directory on the remote computer.
     pwd
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quit

Ends the FTP session with the remote computer and exits ftp.
     quit
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quote

Sends arguments, verbatim, to the remote FTP server. A single FTP reply code is expected in return. Quote is identical to literal.
     quote argument [ ...]

Parameter

argument – Specifies the argument to send to the FTP server.

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recv

Copies a remote file to the local computer using the current file transfer type. Recv is identical to get.
     recv remote-file [local-file]

Parameters

remote-file – Specifies the remote file to copy.

local-file – Specifies the name to use on the local computer. If not specified, the file is given the remote-file name.

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remotehelp

Displays help for remote commands.
     remotehelp [command]

Parameter

command – Specifies the name of the command about which you want help. If command is not specified, ftp displays a list of all remote commands.

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rename

Renames remote files.
     rename filename newfilename

Parameters

filename – Specifies the file you want to rename.

newfilename – Specifies the new filename.

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rmdir

Deletes a remote directory.      rmdir directory

Parameter

directory – Specifies the name of the remote directory to delete.

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send

Copies a local file to the remote computer using the current file transfer type. Send is identical to put.
     send local-file [remote-file]

Parameters

local-file – Specifies the local file to copy.

remote-file – Specifies the name to use on the remote computer. If not specified, the file is given the local-file name.

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status

Displays the current status of FTP connections and toggles.
     status
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trace

Toggles packet tracing; trace displays the route of each packet when running an ftp command.
     trace
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type

Sets or displays the file transfer type.
     type [type-name]

Parameter

type-name – Specifies the file transfer type; the default is ASCII. If type-name is not specified, the current type is displayed.

Notes

FTP supports two file transfer types, ASCII and binary image.

ASCII should be used when transferring text files. In ASCII mode, character conversions to and from the network standard character set are performed. For example, end-of-line characters are converted as necessary, based on the destination’s operating system.

Binary should be used when transferring executable files. In binary mode, the file is moved byte-by-byte.

See Also :

ascii

binary

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user

Specifes a user to the remote computer.
     user user-name [password] [account]

Parameters

user-name – Specifies a user name with which to log in to the remote computer.

password – Specifies the password for user-name. If not specified, but required, ftp prompts for the password.

account – Specifies an account with which to log on to the remote computer. If account is not specified, but required, ftp prompts for the account.

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	Command	Short Description		Command	Short Description
!	Run	mdir	Multiple directory listing
?	Help	mget	Mulitiple get
append	Append to a file	mkdir	Make directory
ascii	Set ASCII transfer type	mls	Multiple listing
bell	Toggle bell	mput	Multiple Put
binary	Set binary trasfer type	open	Connect to FTP server
bye	Terminate ftp session and exit	prompt	Toggle prompting
cd	Change directory	put	Upload file
close	Terminiate FTP session	pwd	Present working directory
debug	Toggle debugging mode	quit	Terminate FTP session and quit
delete	Delete file	quote	Send arbitrary FTP command
dir	Directory listing	recv	Receive file
disconnect	Terminate FTP session	remotehelp	Help from remote server
get	Download file	rename	Rename file
glob	Toggle glob	rmdir	Remove directory
hash	Toggle hash #	send	Send one file
help	Local help	status	Current status
lcd	Change local directory	trace	Toggle packet tracing
literal	Send arbitrary FTP command	type	Show file transfer type
ls	List contects of remote directory	user	Connect as new user
mdelete	Delete multiple files	verbose	Toggles verbose mode

Filed under: FTP Commands Overview

Sailajamehra.. writes for u...

Know about 3G Vs Wi-fi

Know about 3G Vs Wi-fi

· Does WiMAX Threat WiFi?

Precaution at Chat..!!!

Chat Precautions on Net

..written by TejasviJain

Mobile Application

Don’t have Stress At Computer

Cells and Organelles_The Cell Membrane

Java Naming and Directory

JNDI

Names

Binding

InitialContextFactory

Other JNDI operations

Looking Up

Role of JNDI in J2EE

CORBA – part2

CORBA – PART1

FTP – commands

FTP Commands Overview

!

?

append

ascii

bell

binary

bye

cd

close

debug

delete

dir

disconnect

get

glob

hash

help

lcd

literal

ls

mdelete

mdir

mget

mkdir

mls

mput

open

prompt

put

pwd

quit

quote

recv

remotehelp

rename

rmdir

send

status

trace

type

user

***Chat* *Precautions on Net***