JPA and GWT failing.

Question

I'm trying to use JPA with GWT.

My serviceImpl calls

UserDAO.exists(user);

When I run a test case, which calls the same method, with the same parameters, it runs ok. When I do the RPC call, if fails horribly (error at the end).

When I rename persistence.xml to someothername.xml, I get the SAME error, so I'm inclined to think that GWT (in development mode BTW), is NOT reading my persistence.xml.

The error:

Starting Jetty on port 8888
   [WARN] Exception while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract hobarrera.client.dto.main.UserRegDTO hobarrera.client.services.AuthService.selfRegisterUser(java.lang.String,java.lang.String,java.lang.String,java.lang.String) throws hobarrera.client.exceptions.MyCustomizedException' threw an unexpected exception: java.lang.ExceptionInInitializerError
 at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:378)
 at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:581)
 at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:188)
 at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:224)
 at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
 at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
 at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
 at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
 at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
 at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
 at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
 at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
 at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
 at org.mortbay.jetty.Server.handle(Server.java:324)
 at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
 at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
 at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
 at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
 at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
 at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
 at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)
Caused by: java.lang.ExceptionInInitializerError
 at hobarrera.server.DAO.EntityManagerFactory.createEntityManager(EntityManagerFactory.java:13)
 at hobarrera.server.DAO.UsuarioDAO.userNameExists(UsuarioDAO.java:52)
 at hobarrera.server.services.AuthServiceImpl.selfRegisterUser(AuthServiceImpl.java:60)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:616)
 at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:562)
 ... 22 more
Caused by: javax.persistence.PersistenceException: No resource files named META-INF/services/javax.persistence.spi.PersistenceProvider were found. Please make sure that the persistence provider jar file is in your classpath.
 at javax.persistence.Persistence.findAllProviders(Persistence.java:167)
 at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:103)
 at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
 at hobarrera.server.DAO.EntityManagerFactory$RealEntityManagerFactoryContainer.<clinit>(EntityManagerFactory.java:9)
 ... 30 more
[ERROR] 500 - POST /desarrollonew/greet (0:0:0:0:0:0:0:1) 57 bytes
   Request headers
      Host: localhost:8888
      User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.8) Gecko/20100216 Fedora/3.5.8-1.fc12 Firefox/3.5.8
      Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
      Accept-Language: en-us,en;q=0.5
      Accept-Encoding: gzip,deflate
      Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
      Keep-Alive: 300
      Connection: keep-alive
      Referer: http://localhost:8888/desarrollonew/hosted.html?desarrollonew
      Cache-Control: no-cache
      X-GWT-Permutation: HostedMode
      X-GWT-Module-Base: http://localhost:8888/desarrollonew/
      Content-Type: text/x-gwt-rpc; charset=utf-8
      Content-Length: 187
      Pragma: no-cache
   Response headers
      Content-Type: text/plain

[edit]
It seems GWT has it's own persistence.xml file somewhere (for internal use I guess). That's why renaming my persistence.xml to somethingelse.xml still gave the same error: The persistence.xml file which was being read was GWT's all the time.

So now my question is: How do I override it, force the usage of another one, or live without it?

Answer 1

You didn't add the JPA implementation in your classpath. Place in your classpath the jar of datanucleus (or toplink, or whatever you're using), which take care of entity manager creation.

Answer 2

Do you have the DataNucleus jars in WEB-INF/lib?

Answer 3

Since this is like the nth time I'm going to suggest switching to an external server for GWT, let me quote my previous answer (please read the full answer for a more in-depth explanation of GWT's embedded Jetty issues):

I'd recommend just switching to an external Java server (like Tomcat, which you seem to have installed and which works with your configuration) - much less problems, easier than trying to work with the crippled Jetty that comes with GWT.

The instructions can be found in the docs. If you stick with GWT's Jetty, you will only run into more issues in the future.

It's still true, though - the Jetty that comes with GWT is known to be problematic. Read through the docs for instructions on how to use an external server with GWT (easy procedure, IMHO) - no drawbacks and no problems with strange errors/exceptions.