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Embedded Systems October 2000 Vol13_11

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The Web is now part of our daily lives and culture, but it is still somewhat chained to the desktop. WAP is designed to breal< that chain. on the Secure Sockets Layer (SSL) protocol. Data integrity is ensured at this layer, and data is encrypted using a private key algorithm. The Transport Layer contains the WDP, or Wireless Datagram Pro tocol. This layer provides the WAP equivalent of TCP and UDP, with the emphasis on connectionless da tagrams. The Transport Layer allows the upper lay- e rs to operate transparently to the data requirements of the bearer ser- vices. On the bottom of the stack are the Beare r Services. Bearers are the digital phones and the data services they provide. Developing WAP applications There are free WML and WMLScript development tools available on the Web. Two are currently avai lable from Phone .com (forme rly Unwired Planet) and Nokia. The fu ll WML specification set is available from the WAP Forum. The Phone.com tools require a connection to a serve r, but this can be localized by configuring a ~:_'Z=:~;]iThe WAP six-layer protocol stack Proxy Model Application Layer (WAE or wireless application environment) server on the local machine the devel- opment tools are downloaded on. Most develope rs use the free Apache server and configure it locally. The No kia toolset doesn' t require an external server, although you can use one if you like. The Nokia develop- ment kit requires the J ava runtime library, and recommends 64MB of RAM. Both developme nt toolsets have well-t1lOught-out user interfaces, and each has a virtual phone handset on the right of the screen where you can see your WML/ WMLScript applica- tion in action. I Contains User Agents, WMl, WMlScript, and WTA applications. Go forth The Web is now part of our daily lives and culture, but it is still somewhat chain ed to the desktop. WAP is designed to break tha t chain. Embedded systems programmers have a great opportu nity to create WAP applications for wireless and wi red platforms yet to be imagined. esp Session Layer (WSP or wireless session protocol) Supports two services: connection less and connection-oriented. Transaction layer (WTP or wireless transaction protocol) Supports three classes of transactions: unreliable one-way requests, reliable one-way requests, and reliable two-way requests. JefJ SteJan is a system engineer at OnStar. He has worked in embedded syste?nS soft- ware Jor many yean, is a frequent slJeaker at the Embedded Syste?nS ConJerences, and is the author. oj over 15 software articles. He is currently wr.iting his fint book, enti- tled Embedding Artificial Intelligence. His e-mail address is jmste slm ng. ,om. Jan@mind- Security Layer (WTlS or wireless transport layer security) Provides session-layer data encryption. Resources WAP Forum. This is the WAP mother ship. The full set of WAP technical specifica- tions are found on the WAP technical link: www.wapforum.org. Transaction layer (WDP or wireless datagram protocol) Supports WAP version of TCP or UDP. Responsible for packet fragmentation, reassembly, and maintenance of end-to-end service. Nokia Wireless Data Forum. This offers a WAP server trial kit and the Nokia WAP Toolkit along with a well written docu- mentation set that's loaded with good examples. The WAP Toolkit is free but requires developer registration: www. forum.nokia.comldeveloperslwapl. Bearers GSM CDMA CDPD This is the physical interface to telephony and wireless hardware and their services. Phone.com. Go to the Developer Web Site to download the development kit. Like Nokia, the toolkit is free but requires registration: www.phone.comldevelop- erslindex.html. 58 OOOBER 2000 Embedded Systems Programming

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