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Wireless Application Protocol - WAP

Where does WAP Fit in the Wireless Computing Application?

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 Ė residing in the client handheld device
  2. WAP Gateway Ė typically on wireless ISPís network infrastructure
  3. WAP Server  - residing either on ISPís infrastructure or on enduser organizationís infrastructure

WAP Micro-browser
A WAP micro-browser is a client software designed to overcome challenges of mobile handheld devices that enables wireless access to services such as Internet information in combination with a suitable network server

Lots of WAP browsers and emulators are available free of cost which can be used to test your WAP pages. Many of these browsers and emulators are specific to mobile devices. For example the R380s WAP emulator is intended to be used for testing WML applications developed for the WAP Browser in the Ericsson Smartphone R380s. You can find a list of downloadable WML Browsers/ Emulators at  www.2thumbswap.com/downloads/index.htm.

WAP emulators can be used to see how your site will look like on specific phones. As these images show, the same thing can look different on different mobile phones. So, the problems that web developer faces with the desktop browsers (Netscape/Iexplorer) is present here also. So, make sure you test your code on different mobile phones (or simulators)

WAP Products - Microbrowser, WAP Gateway, WAP servers

WAP Gateway
The idea behind WAP specifications is to connect the mobile networks to the Internet.

To connect these two mega-networks, the WAP Specification assumes there will be a WAP Gateway. At its simplest level, this is a stack converter, which will convert the WAP request into a Web request and the Web response into a WAP response.

WAP Gateway is a piece of software that sits between the mobile device and the external network like the Internet. The gateway does the job of converting Internet content i.e. the WML pages into byte code (WMLC) which can be understood by a WAP device. Usually located on a server of a mobile operator it handles incoming requests from your WAP phone, takes care of the conversion required during WTLS/SSL sessions and handles incoming requests from your WAP phone. Although in theory, the gateway could also be made to convert the HTML page content itself on-the-fly as well, there are some problems. HTML pages can be full of graphics and with inline scripting. Converting these to WML may return something that is not of any relevance to anybody.

Some of the WAP Gateway products that are now coming on to the market (such as Nokia's WAP Server) also provide hosting capabilities themselves. In future it could be possible to integrate your WAP Server into the mobile network to gain information about the subscriber's location.

If you host your own gateways, then it may be required to maintain some sort of connection with the mobile network. For example, in case of GSM networks you may need to have say a dial up connection with the network's SMS engine or you may need to provide dial in modems for CSD access (Circuit Switched Data, around 9.6 kbps data rate)

  Source: WAP for web developers, anywhereyougo.com

There is a large list of available gateways at wapdrive.net. You can get your WAP gateway form

A WAP server is simply a combined web server and WAP gateway. WAP devices do not use SSL. Instead they use WTLS. Most existing web servers should be able to support WAP content as well. Some new MIME types need to be added to your web server to enable it support WAP content. MIME stands for Multipurpose Internet Mail Extension, and in the web context, MIME can be thought of as a piece of header information that comes down with every file sent from a web server to a browser.

The following types basically need to be added:

  • text/vnd.wap.wml for .wml files (WML source files)

  • application/vnd.wap.wmlc for .wmlc files (WML compiled files)

  • text/vnd.wap.wmlscript for .wmls files (WMLScript source files)

  • application/vnd.wap.wmlscriptc for .wmlsc files (WMLScript compiled files)

  • image/vnd.wap.wbmp for .wbmp files (wireless bitmaps)

On Microsoft Servers, there's a HTTP header tab on the Management Console. On Apache servers, you use an .htaccess file.

When you are accessing a secure service (using WTLS) the data is sent encrypted to the WAP gateway. The gateway decrypts it and encrypts it using SSL before passing it on to the web server. When the data returns, it will be decrypted and encrypted using WTLS before being sent to your WAP device. By combining the web server and the WAP gateway it is possible to enhance the overall security in these operations involved.

WAP Servers and Gateways

A list of Gateways/Servers can be found at: www.2thumbswap.com/downloads/index4.htm

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(Dedicated to providing comprehensive information to mobile computing community of IT professionals, user organizations, and vendors)