WIRELESS APPLICATION PROTOCOL

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INTRODUCTION
The primary means of communicating information of these days are voice and Internet. The unlimited accesses to Internet and sheer number of people connected to the Internet have made industry captain realize its potential. The industry now plans its marketing and communication strategies around the Internet. Today every banking to education, research to health-care is affected by it. E-mail is the way to communicate today. Practically who use the Internet uses E-mail. The wireless technologies and the Internet were growing separately. The wireless industry initially struggled within a number of issues like low bandwidth and low connection stability, to bring Internet to its users. They came together to form a common forum to tackle these issues. This forum is called the WAP.The wireless application protocol.
The Wireless Application Protocol is a standard developed by the WAP Forum, a group founded by Nokia, Ericsson, Phone.com (formerly Unwired Planet), and Motorola. The WAP Forum’s membership roster now includes computer industry heavyweights such as Microsoft, Oracle, IBM, and Intel along with several hundred other companies. According to the WAP Forum, the goals of WAP are to be:
• Independent of wireless network standard.
• Open to all.
• Proposed to the appropriate standards bodies.
• Scalable across transport options.
• Scalable across device types.
• Extensible over time to new networks and transports.
WAP defines a communications protocol as well as an application environment. In essence, it is a standardized technology for cross-platform, distributed computing. It sound similar to the World Wide Web. WAP is very similar to the combination of HTML and HTTP except that it adds in one very important feature: optimization for low-bandwidth, low-memory, and low-display capability environments. These types of environments include PDAs, wireless phones, pagers, and virtually any other communications device.
Wireless Application Protocol (WAP) is a result of continuous work to define an industry-wide specification for developing applications that operate over wireless communication networks. The scope for the WAP Forum is to define market is growing very quickly and reaching new customers and providing new services. To enable operators and manufacturers to meet the challenges in advanced services, differentiation, and fast/flexible service creation, WAP defines a set of protocols in transport, session and application layers.
WAP As An Extension of the Internet model
The WAP model closely resembles the Internet model of working. In Internet a WWW client requests a resource stored on a web server by identifying it using a unique URL, that is, a text string constituting an address to that resource. WAP client applications make requests very similar in concept to the URL concept in use on the Web.Standard communication protocols, like HTTP and Transmission Control Protocol/Internet Protocol (TCP/IP) manage these requests and transfer of data between the two ends. The content that is transferred can either be static like html pages or dynamic like Active Server Pages (ASP), Common Gateway Interface (CGI), and Servlets.
The following figure helps draw a parallel to the Internet protocols. You can see how WAP extends or reuses Internet protocols to achieve mobile Internet access.
The strength of WAP (some call it the problem with WAP) lies on the fact that it very closely resembles the Internet model. In order to accommodate wireless access to the information space offered by the WWW, WAP is based on well-known Internet technology that has been optimized to meet the constraints of a wireless environment. Corresponding to HTML, WAP specifies a markup language adapted to the constraints of low bandwidth available with the usual mobile data bearers and the limited display capabilities of mobile devices - the Wireless Markup Language (WML). WML offers a navigation model designed for devices with small displays and limited input facilities (no mouse and limited keyboard). WAP also provides a means for supporting more advanced tasks, comparable to those solved by using for example JavaScript in HTML.
THE WAP MODEL
A WAP request is routed through a WAP gateway which acts as an intermediary between the “bearer” used by the client (GSM, CDMA, TDMA, etc.) and the computing network that the WAP gateway resides on (TCP/IP in most cases). The gateway then processes the request, retrieves contents or calls CGI scripts, Java servlets, or some other dynamic mechanism, then formats data for return to the client. This data is formatted as WML (Wireless Markup Language), a markup language based directly on XML. Once the WML has been prepared (known as a deck), the gateway then sends the completed request back (in binary form due to bandwidth restrictions) to the client for display and/or processing. The client retrieves the first card off of the deck and displays it on the monitor.
The deck of cards metaphor is designed specifically to take advantage of small display areas on handheld devices. Instead of continually requesting and retrieving cards (the WAP equivalent of HTML pages), each client request results in the retrieval of a deck of one or more cards. The client device can employ logic via embedded WMLScript (the WAP equivalent of client-side JavaScript) for intelligently processing these cards and the resultant user inputs.
To sum up, the client makes a request. This request is received by a WAP gateway that then processes the request and formulates a reply using WML. When ready, the WML is sent back to the client for display. As mentioned earlier, this is very similar in concept to the standard stateless HTTP transaction involving client Web browsers.
Three are three essential product components that you need to extend your host applications and data to WAP-enabled devices. These three components are:
1. WAP Microbrowser – residing in the client handheld device
2. WAP Gateway – typically on wireless ISP’s network infrastructure
3. WAP Server - residing either on ISP’s infrastructure or on enduser organization’s infrastructure .