How can I turn an Eclipse GWT/GAE app into an Eclipse Tomcat/mySQL app?

Sorry in advance for the long post but the problem I am facing here is quite crucial for me, so here we go...

I have a Eclipse GWT (2.0) Web Application using the the GAE and making transactions with its datastore. On the other hand I would like to make sure that I can also deploy this web application on another infrastructure than the Google App Engine. Therefore I wanted to debug my web app using another servlet container (Tomcat 6) and another datastore (mySQL or MSSQL or any other, it doesn't really matter for now.)

In order to be able to debug an Eclipse web app with Tomcat it has to carry the Dynamic Web Project facet. If it doesn't then the new server that I add to Eclipse within Servers refuses to pick my GWT module in its list of supported apps. And not only GWT Web Apps don't carry it, but they don't even allow to alter the project's facets at all! However, I found that adding the few relevant tags to the .project file can make it eligible within Eclipse to allow new project facets additions. Here are the tags I used:

<nature>org.eclipse.jdt.core.javanature</nature>
<nature>com.google.开发者_JS百科gwt.eclipse.core.gwtNature</nature>
<nature>org.eclipse.wst.common.project.facet.core.nature</nature>
<nature>org.eclipse.wst.common.modulecore.ModuleCoreNature</nature>
<nature>org.eclipse.jem.workbench.JavaEMFNature</nature>
<nature>org.eclipse.wst.jsdt.core.jsNature</nature>
<nature>com.google.appengine.eclipse.core.gaeNature</nature>

So I did that, I could "turn" the project into an Eclipse's Dynamic Web Project and by doing so made it compliant to be added to the list of modules handled by - let's say - Tomcat 6 within Servers. So that is exactly what I wanted, I can now switch between two debug configurations at will in Eclipse in order to debug my GWT web app either on the App Engine or on Tomcat.

The problem is that adding the Dynamic Web Project facet disturbs the DataNucleus enhancer. For some reason, once the project has become a Dynamic Web Project, it seems that the enhancer is never called anymore and I get this error message saying that some classes haven't been enhanced. Playing with the Google... App Engine... ORM classes or checking/unchecking the Enhancer in Builders wouldn't change anything. Please note that the enhancer issue affects both debug configurations: Tomcat as well as the App Engine.

So I was thinking of two solutions.

(1) Disable the Google plugin's DataNucleus enhancer and perform the enhancements myself. So I installed the DataNucleus plugin to configure project specific enhancements by following their guide about the Eclipse plugin. They say that by right-clicking on the project one can activate DataNucleus support for the given project's files. Unfortunately, after installing the latest version of their plugin for Eclipse, no such right-click menu appears! I have therefore no way to tell their plugin that I want to activate the enhancements on a given project! How frustrating is that?? (I uninstalled/reinstalled the plugin, let perform plenty of pending Eclipse updates... but still no right-click menu.) Does anyone know of another way to activate DataNucleus enhancement? For now I would be happy even with a pretty manual trick as it is very critical for me to be able to perform this cross-servlet container debugging within Eclipse.

(2) Use this tip from the official GWT website http://code.google.com/webtoolkit/doc/latest/FAQ_DebuggingAndCompiling.html#How_do_I_use_my_own_server_in_hosted_mode_instead_of_GWT%27s Ok that works, and for now let's say that it saves my life BUT... it requires hosted mode and therefore doesn't allow the use of GWT 2.0. So regarding this workaround I would like to know if there is a way to do something similar under GWT 2.0?

Turning the GWT Web App into a Eclipse Dynamic Web Project would be the ideal solution for pursuing the development of my application. As I said above, that way, it is very convenient to switch from the App Engine to Tomcat and vice versa. So I favour workaround (1) over workaround (2). But anyway, some help or piece of advice regarding any of the two points will be very very welcome.

Thank you for reading this very long post!

I always use Google Plugin (GPE) for GWT development even when I deploy to Tomcat, where I simply disable GAE option.

Perhaps, I don't understand the question - but I have had no problems debugging my app running on jetty and then transferring the app to Tomcat. Are there any issues that I need to learn?

In fact, even when my app is plain jsp or servlets, without any GWT, I still used GPE. But GPE would refuse to run jetty without either GWT or GAE enabled. So I simply create a dummy GWT app. In all my years, I had never had to worry about differences between jetty and tomcat. And if I had to write an app where I had to exploit the differences in tomcat over jetty, I would consider myself a lousy programmer.

The only reason I see to push JEE server into an external server, is for profiling the app as it runs on tomcat.

JEE is JEE, whether Tomcat or Jetty. I have heard that some people have a bias against using Jetty, like preferring starbucks over neighbourhood cafe. Coffee is coffee.

I don't understand. May be you could write another thesis to explain why you cannot debug on jetty and then deploy on tomcat.

I ran into the exact same problem, I could edit the properties of my project and see the datanucleus menu in the context so the plugin was definitely working. My issue was I was using the "Java EE" perspective in eclipse. (Juno btw). I switched to the "Java" context and my datanucleus menu was back and I was able to enable support and enable automatic enhancement.

Window -> Show perspective -> Other -> Java