tapestry/src/site/apt/javascript/packaging.apt

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JavaScript Reference - Packaging
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Jesse Kuhnert
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26 July 2006
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Packaging

  The Tapestry javascript API uses the dojo 
  {{{http://manual.dojotoolkit.org/WikiHome/DojoDotBook/BookModules}packaging system}} to include
  both dojo and Tapestry javascript files on the fly.
  
  This means that most of the API is broken up over a number of files that will be optionally included
  automatically - only when you need them. As an example, this is how you would import the Tapestry 
  form related functions onto your page:
  
+-------------------------
<script type="text/javascript">
	dojo.require("tapestry.form");
	
	tapestry.form.submit(dojo.byId("myform"));
</script>
+-------------------------

* Download/Performance concerns of included JavaScript

  A very valid concern that a lot of users will worry about is the performance impact of including all of
  this JavaScript on their pages! This is still a very grey area that may change to meet real world needs
  as they come up, but the following is the current thinking behind this:
  
  * The bundled {{{http://dojotoolkit.org}dojo}} core javascript file that is included by default is 
    only about <<<176k>>> in size. This is fairly small compared to the average size of most images displayed
    in web applications. 
    
  * Part of the beauty of the dojo {{{http://manual.dojotoolkit.org/WikiHome/DojoDotBook/BookModules}packaging}} 
    system is that you can build very small core javascript files and only have your web application incur performance
    hits for additional functionality <(like widgets)> when you need it. This should keep your app nice and slim
    in most areas.
    
  * Overhauled Tapestry {{{../apidocs/org/apache/tapestry/asset/AssetService.html}AssetService}} 
  	implementation that does a much better job at properly interpreting and setting the correct browser cache 
  	settings on included asset resources, like dojo and Tapestry javascript API files/resources. It even goes as far
  	as serving up the files via a new hivemind configuration point that eliminates the need to have an MD5 hash 
  	string in the include URL's, making application restarts have no effect on user browser caching of your 
  	javascript files.
  
  []
  
  As mentioned previously, this area of Tapestry is not set in stone. The new move to 
  {{{http://maven.apache.org}maven2}} has made doing snapshot updates of Tapestry very easy, so if/when 
  issues are found/addressed people should be able to get updated versions pretty quickly.