The Tapestry javascript API uses the dojo 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">

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 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 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 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 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.