Hosting Apache Tapestry5.1 on GAE (Google App Engine)

Assalam Alikom

In this post, I'll try to explain the steps I took to host Tapestry5.1 on google app engine.

First of all here is my application.

A very good place to start is here. This page will help you know what will, won't or will partially work on Google app engine.

Now straight to tapestry5.1 stuff ..

1)AppModule.java

public class AppModule {
public static void contributeApplicationDefaults(MappedConfiguration config)   {
  config.add(SymbolConstants.PRODUCTION_MODE, "false"); //This mainly affects how exceptions are reported, I'm   not sure - and I don't think - its vital to host tapestry   on GAE.
  config.add("tapestry.thread-pool-enabled", "false"); //Now this is a must !, GAE restriction.
  config.add(SymbolConstants.APPLICATION_VERSION, "0.1");// This is to override the random number generated by tapestry in assets paths
 }
}

2)There as a compatibility issue between tapestry5 and GAE, that's why your are obviously here !, this issue has been patched and the patch is applied to the online tapestry5 trunk here. 

1. Check it out (No, actually check-it out !)
2. Compile it, skip the tests that maven runs if you face problems (and this is your own responsibility to do so.)
3. Replace the tapestry jar files you're using with the ones you just compiled.

3)If you are using eclipse, I encourage you to download and install the Google app engine eclipse  plug-in. Specially if you'll use JDO which is explained by Google regarding it's utilization in the GAE environment.

4)Now there are some issues regarding tapestry components static files:

• It's important to know that Google App Engine hosts static files on different servers than the ones that serve the servlets . 
• Also tapestry has it's procedures to serve assets. Fortunately this can be handled regarding hosting tapestry on Google application engine.
• About "tapx" tapestry extensions,it doesn't obey the configuration we add to the AppModule.java class regarding the app-version property ! (I didn't try examining this locally). Too bad this is not on haward's priority list. Btw, haward is tapestry's creator, you probably know that !

The following image is a snapshot for tapestry 5.0.18 hosted on GAE (It's sometimes showed properly but I got lucky catching this snapshot to demonstrate my point) :

As you can see, the style is broken, because the .css stylesheet file url is broken !

The online website is here.

I REALLY hope tapestry becomes fully compatible with GAE. It's literally like a dream come true. A magnificent development environment and a free, reliable and powerful host like GAE !!

Haward..PLEASE make Tapestry fully compatible with GAE XD

Thank you all for reading I hope you made use of this :)