JSP Tag Libraries

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<card id=»image»

ontimer=»#login» title=»Cosmetix»>

<timer value=»100″/>


<img src=»images/logo.wbmp» alt=»Cosmetix»/>



<card id=»login»


<do type=»Login»>

<go href=»somewhere.wml»/>


<p align=»left»>

<input type=»text»

name=»username» format=»32A» title=»Username:»/>

<input maxlength=»32″ type=»password» size=»7″ name=»passwd» title=»Password»/>





It is possible for the deck to contain just one card.

The big picture

Why are we discussing WAP in a book concerned with custom JSP tags? Because WAP and the pervasive cellular devices are much more than another client type. There are many more mobile phones than computers in use today and, although most of those phones cannot yet access the Internet, most market research suggests it won’t be long before there are more wireless than standard wired clients. Other technologies, such as VoiceXML, extend the web paradigm even further by enabling users to browse web sites using only their voice from any standard telephone. Imagine how large your potential user base becomes when anyone in the world with access to a phone can visit your site. This increase in nontraditional web clients is likely to continue to grow, making the Internet as ubiquitous and accessible as one can imagine. As a result of these growing trends, it is important to keep in mind that application designs will be targeting a multitude of presentation types.

Using custom JSP tags with a well-designed Java component layer can help your web application accommodate these different device types. The advantages tags offer in this arena are their content-agnostic behavior, that is, custom JSP tags don’t have any predisposition to HTML, and can seamlessly support returning HTML, WML VoiceXML, or any other markup language you choose. Also, since alternative client types work (at some level) with Internet cornerstones such as HTTP, any tags that you write to handle cookies, request parameters, and the like can be reused for different client types. Moreover, with JSP custom tag libraries defined in the widely accepted and popular J2EE standard, it is very likely that third-party tag libraries will become prevalent.

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