Wireless Application Protocol

Wireless Application Protocol Muhammad Mahboob Elahi(BS Electronics-5th semester) Samiullah Babar(BS Electronics-5th semester) Farooq Baig(BE Electronics-5th semester) Abstract While the evolution of cellular networks has resulted in many mobile services, such services are primarily for voice. Mobile phone users do have the desire to access the Internet. However, Internet protocols are not designed to operate efficiently over mobile networks.

WAP, the standard developed by the WAP forum, addresses these issues nicely by adapting to the restrictions of the wireless network – low bandwidth, small display, limited input facilities, limited memory and CPU, and less connection stability. WAP interfaces with different entities through the use of a gateway/proxy and a set of lightweight data presentation/formatting scripts. Such scripts allow information to be formatted in such a manner that is suitable for transmission over wireless and for presentation on a small wireless device with limited display capability.

In this paper, I will deal with the overall WAP model and architecture. . Key Words- Wireless Application Protocol BEE-5 IIHE. 1. Introduction While the evolution of cellular networks has resulted in many mobile services, such services are primarily for voice. Mobile phone users do have the desire to access the Internet. Hence, efforts were made to enhance the capability of mobile phones and devices. WAP is an open protocol for wireless multimedia messaging. WAP (Wireless Application Protocol) allows the design of advanced, interactive, and real-time mobile services, such as mobile banking or Internet-based news and travel services. 1] The Wireless Application Protocol (WAP) refers to a group of related technologies and protocols widely used as a de-facto standard protocol in providing Internet access to mobile phones or other thin-client devices. [3] Internet protocols are not designed to operate efficiently over mobile networks. Standard HTML web content cannot be displayed fully on the small-size screens of wireless devices, pagers, and mobile phones. WAP addresses these issues nicely. WAP is a license-free wireless protocol standard that can bring data information and telephony services to wireless devices. 1] In the mid 1990s, Ericsson made advances in value-added services on the mobile networks through the creation of the Intelligent Terminal Transfer Protocol (ITTP). Nokia and others, however, made advances in device user interfaces, such as Handheld Device Markup Language (HDML) and HDTP (Handheld Device Transport Protocol). HDTP can be viewed as a new, lightweight protocol optimized for client/server transactions over wireless links. Further, Nokia again made advancement through the introduction of the smart short message services (SMS) concept, which allows GSM users to access services present in the Internet.

With such fragmentation of effort by different companies, a joint effort for a widely acceptable standard became a necessity. Hence, WAP was born. [1] 2. History The WAP Forum dates from 1997. It aimed primarily to bring together the various wireless technologies in a standardized protocol. In 2002 the WAP Forum was consolidated (along with many other forums of the industry) into OMA (Open Mobile Alliance), which covers virtually everything in future development of wireless data services. [5] 2. 1. WAP 1. X The WAP 1. standard, released in April 1998, described a complete software stack for mobile internet access. WAP version 1. 1 came out in 1999. WAP 1. 2, the final update of the 1. X series was released in June 2000. The most important addition in version 1. 2 was WAP push. [5] 2. 2. WAP Push WAP Push has been incorporated into the specification to allow WAP content to be pushed to the mobile handset with minimum user intervention. A WAP Push is basically a specially encoded message which includes a link to a WAP address. [pic] Figure 1. WAP Push Process Source: http://en. wikipedia. org/wiki/Wireless_Application_Protocol

WAP Push is specified on top of WDP; as such, it can be delivered over any WDP-supported bearer, such as GPRS or SMS. Most GSM networks have a wide range of modified processors, but GPRS activation from the network is not generally supported, so WAP Push messages have to be delivered on top of the SMS bearer. On receiving a WAP Push, a WAP 1. 2 or later enabled handset will automatically give the user the option to access the WAP content. This is also known as WAP Push SI (Service Indication). The network entity that processes WAP Pushes and delivers them over an IP or SMS Bearer is known as a Push Proxy Gateway (PPG). 5] 2. 3. WAP 2. 0 WAP 2. 0, released in 2002, a re-engineered WAP, uses a cut-down version of XHTML with end-to-end HTTP (i. e. , dropping the gateway and custom protocol suite used to communicate with it). A WAP gateway can be used in conjunction with WAP 2. 0; however, in this scenario, it is used as a standard proxy server. The WAP gateway’s role would then shift from one of translation to adding additional information to each request. This would be configured by the operator and could include telephone numbers, location, billing information, and handset information.

Mobile devices process XHTML Mobile Profile (XHTML MP), the markup language defined in WAP 2. 0. It is a subset of XHTML and a superset of XHTML Basic. A version of cascading style sheets (CSS) called WAP CSS is supported by XHTML MP. [5] 3. What is the purpose of WAP? To enable easy, fast delivery of relevant information and services to mobile users. [2] 3. What type of devices will use WAP? Handheld digital wireless devices such as mobile phones, pagers, two-way radios, Smartphone, and communicators — from low-end to high-end. [2] 4. Which wireless networks does WAP work with?

WAP is designed to work with most wireless networks such as CDPD, CDMA, GSM, PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA, DECT, DataTAC, Mobitex. [2] 5. Which operating system is compatible with WAP? WAP is a communications protocol and an application environment. It can be built on any operating system including PalmOS, EPOC, Windows CE, FLEXOS, OS/9, JavaOS, etc. It provides service interoperability even between different device families. [2] 6. The WAP Forum In 1997, Ericsson, Motorola, Nokia, and Unwired Planet formed the WAP Forum (www. wapforum. org).

More than 90 companies in the wireless telecommunications business are members of the WAP Forum. WAP is the standard developed by the WAP Forum, a consortium formed by device manufacturers, service providers, content providers, and application providers. WAP specifies an application framework and protocols for wireless devices. WAP is a kind of fusion of mobile networking technologies and Internet technologies. [1] The WAP Forum’s objectives include: i. To bring Internet content and advanced data services to digital cellular phones and other wireless terminals. ii.

To create an interoperable wireless protocol specification that will work across differing wireless network technologies. iii. To enable the creation of content and applications that could scale across a wide range of wireless bearer networks and device types. iv. To embrace and extend existing standards and technologies The key features provided by WAP include: i. A programming model similar to the Internet ii. Wireless Markup Language (WML) iii. WMLScript iv. Wireless Telephony Application (WTA) v. Optimized protocol stack [1] 7. The WAP Architecture There are three major parts of a WAP-enabled system as shown in Figure 3. . WAP Gateway 2. HTTP Web Server 3. WAP Device 7. 1. WAP Gateway WAP gateway acts as mediator between Cellular device and HTTP or HTTPS web server. WAP gateway routes requests from the client (Cellular Phones) to an HTTP (or Web) server. The WAP gateway can be located either in a telecom network or in a computer network (an ISP). [4] 7. 2. The HTTP Web Server Receive the request from WAP Gateway and process the request and finally sends the output to the WAP Gateway, which in turn the sends this information to the WAP device using its wireless network. [4] 7. 3. The WAP Device

WAP device (Cellular phones) is part of wireless network. WAP Device sends the WAP request to the WAP Gateway, which in turn translates WAP requests to WWW requests, so the WAP client is able to submit requests to the Web server. After receiving the response from the HTTP Web Server, WAP Gateway translates Web responses into WAP responses or a format understood by the WAP client and sends it to the WAP Device. [4] 8. WAP Protocol Stack For those of you who want to understand the deep down, nitty-gritty of the WAP, here’s a quick summary. The WAP relies on stacked architecture, as does

UNIX, Windows NT, and most other newer technologies. Because wireless devices have limited memory, some layers of the stack have been offloaded to the WAP gateway (which is part of the service providers” system). [4]The layers, from top to bottom, are: • the application layer, which relies on the Wireless Application Environment (WAE) • the session layer, which relies on the Wireless Session Protocol (WSP) • the transaction layer, which relies on the Wireless Transaction Protocol (WTP) • the security layer, which relies on the Wireless Transport Layer Security (WLTS) • the transport layer and the network layer. [4] 9. The WAP service model In the current Internet model, the client runs a copy of the Web browser, which uses the underlying Internet protocols to access useful content residing in a server in the network. Such interactions occur through using HTTP request and reply messages. WAP is based on an Internet technology that has been optimized to address the constraints of wireless links and wireless devices. Services created by HTML do not usually fit well on small handheld wireless devices due to their display limitations.

In addition, such devices do have limited storage and computing capability, and this implies that excessive or redundant information is not welcome. Hence, WML is used instead HTML. WML pages can be also be encoded in binary format to reduce the amount of data to be transmitted over the wireless interface. [1] The WAP service model reveals the presence of a WAP proxy, which is responsible for protocol conversion and data formatting. It acts as the interface between the wired and wireless worlds. These two environments have extreme differences, such as available bandwidth, bit error rates, and storage and processing capabilities.

When a mobile device requests information via the WAP, it is intercepted and interpreted by the WAP proxy, which then forwards the request via HTTP on behalf of the mobile device to the appropriate HTTP server in the network. When the proxy receives the information in response to its earliest request, the information is stored and converted (formatting) to a suitable form for processing and display on the mobile device using the WAP protocol. [1] i. The user selects an option on their mobile device that has a URL with WML content assigned to it. ii.

The phone sends the URL request via the phone network to a WAP gateway, using thebinary encoded WAP protocol. iii. The gateway translates this WAP request into a conventional HTTP request for the specified URL, and sends it on to the Internet. iv. The appropriate Web server picks up the HTTP request. v. The server processes the request, just as it would be any other request. If the URL refers to a static WML file, the server delivers it. If a CGI script is requested, it is processed and the content returned as usual. vi. The Web server adds the HTTP header to the WML content and returns it to the gateway. ii. The WAP gateway compiles the WML into binary form. viii. The gateway then sends the WML response back to the phone. ix. The phone receives the WML via the WAP protocol. x. The micro-browser processes the WML and displays the content on the screen. [1] 10. Adapting to the Restriction of the Wireless Network 10. 1. Low Bandwidth The size of an average HTML page these days, including graphics, is around 20KB. With a 56 Kbps modem, the download time for this page would be in the region of 4 seconds. As the bandwidth of a wireless network is around 9. Kbps, however, the download time for the data equivalent of just that one page would be around 17 seconds. That is not making any allowances for the network itself being slow due to congestion, or for latency. The majority of mobile users are not aware of access speeds, and they should have to care about the differences in access methods to get the same perception of performance. WAP addresses this bandwidth issue by minimizing the traffic over the wireless interface. WML and WMLScript are binary encoded into a compact form before they are transmitted, in order to minimize the bandwidth restriction. [1] 10. 2.

Less Connection Stability and Unpredictable Bearer Availability Wired network access provides a more or less reliable connection to the network. That is not the case in wireless networks, where the bearers might be inaccessible for shorter or longer periods of time due to fading, lost radio coverage, or deficient capacity. If you have ever lost a connection when you were driving in your car, you will know just how frustrating this can be. The architects of the WAP protocol infrastructure, when putting together the specifications for WAP, have taken the problem of connection stability into account and have designed into the layers. 1] 10. 3. Small Display Instead of using the flat document structure that HTML provides, WML structures its document in decks and cards. A card is a single unit of interaction with the end-user, such as a text screen, a selection list, an input field, or a combination of those. A card is typically small enough to be displayed even on a small screen. When an application is executed, the user navigates through a series of cards-the series of cards used for making an application is collected in a deck. [1] 10. 4. Limited Memory and CPU

Wireless devices are usually not equipped with large amounts of memory or computational power in comparison to desktop computers. The memory restriction applies to RAM as well as ROM. Even though it is likely that more memory and more powerful CPUs will be available in the near future, the relative difference will most probably remain. WAP handles these restrictions by defining a lightweight protocol stack. The limited set of functionalities provided by WML and WMLScript makes it possible to implement browsers that make small claims on computational power and ROM resources.

When it comes to RAM, the binary encoding of WML and WMLScript helps to keep the amount of RAM used as small as possible. [1] 11. The WAP Protocol Architecture The WAP architecture provides a scalable and extensible environment for application development on mobile communication devices. It achieves this through a layered protocol design, covering protocols at Layer 4 and above. The WAP protocol stack is independent of the underlying network, which could take the form of GSM, CDMA, CDPD, iDEN, etc. Hence, WAP is essentially an application stack specification; it is not network-centric. 1] 11. 1. Wireless Application Environment (WAE) Generally, WAE enables a spectrum of applications to be supported over WAP. WAE has two main elements, namely: (a) user agents, and (b) services and formats. The former includes the WML and WTA (Wireless Telephone Application) user agents. The latter consists of WML scripts, image formats, etc. A user agent can take the form of a Web browser. The WML user agent is responsible for the interpretation of WML and WMLScript. WAP employs the same addressing model as in the Internet, that is, it use Uniformed Resource Locators (URLs).

A URL uniquely identifies an available resource. WAP also uses Uniform Resource Identifiers (URIs) to address resources that are not accessed via well-known protocols. [1] 11. 2. Wireless Session Protocol (WSP) The WSP provides both connection-oriented and connectionless services. It is optimized for low-bandwidth networks with relatively long latency. WSP is a binary version of HTTP version 1. 1, but with the additions of: (a) session migrations, (b) header caching, etc. WAP connection mode allows the establishment of sessions between a client and the WAP gateway or proxy.

It can handle session interruptions as a result of mobility and reestablish session states at a later point in time. Header caching allows better bearer utilization since in HTTP; most of the requests contain static headers that need to be re-sent again. [1] 11. 3. Wireless Transaction Protocol (WTP) WTP is designed for transaction-style communications on wireless devices. In a transaction, users express their intentions and financial commitments to service providers for processing. Very often, such transactions demand reliable, fast, and secure communications. WTP is a lightweight protocol suitable for implementation in thin clients.

WTP implements selective retransmission of lost segments. [1] 11. 4. Wireless Transport Layer Security (WTLS) WTLS is needed for WAP to ensure data integrity, privacy, authentication, and protection from denial-of-service. It is based on Transport Layer Security (TLS) 1. 0, but optimized for wireless channels. It provides transport layer security between a WAP client and the WAP gateway/proxy. Digital certificates are used for authentication and no repudiation of server and client. Encryption is also used to enhance the degree of confidentiality. [1] 11. 5. Wireless Datagram Protocol (WDP)

WDP is the transport layer protocol in WAP. It has the same functionality provided by the Internet User Datagram Protocol (UDP). Whether WAP uses UDP or WDP, datagram delivery services are provided by port number functionality and the characteristics of different bearer services are hidden from the upper layers. WDP can be extended to provide segmentation and reassembly functions. [1] 12. The Future of WAP The future of WAP depends largely on whether consumers decide to use WAP devices to access the Web, and also on whether a new technology comes along that would require a different infrastructure than WAP.

On the consumer side, the factors largely involve the limitations of WAP and of handheld devices: the lower bandwidth, the limited input ability, and the small screens all require user to adapt from their regular Web-browsing expectations. The bottom line is that WAP is not and can never be the Web on your mobile phone. On the technological side, it is true that mobile phone data speeds will get faster, and this may require a different infrastructure, which will require different handsets to carry the technology.

The new challenger is GPRS (General Packet Radio Service) and Mobile IP. Also, Web browser for the PC will also soon come with the ability to view WAP pages. What this means to the average user is that the instant information access available to mobile users can be combined with the rich content of the Internet. You will simply have two windows open on the PC-one for the traditional content and the other for the WAP content-thereby having the best of both worlds. [1] 13. Acknowledgment

It has been a great pleasure for us to study, research and compile the manuscript on the WAP, which indeed enhanced our knowledge and skills regarding this latest technology. We would like to thank our respected course instructor Sir Rehan Adil for providing us the opportunity to acquire knowledge about this innovative technology. We are grateful to the companies and people for the data provided on the internet to share the knowledge, especially Wikipedia, HowStuffWorks, different whitepapers related to fiber optics, and Wikimedia for providing the images required. 4. Conclusion In this paper, we examined WAP, a protocol that has been standardized and deployed. WAP allows the introduction of mobile Internet services into mobile wireless devices via mobile cellular networks. WAP interfaces with different entities through the use of a gateway/proxy and a set of lightweight data presentation/formatting scripts. Such scripts allow information to be formatted in such a manner that is suitable for transmission over wireless and for presentation on a small wireless device with limited display capability.

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