Allow JDO objectstore to run on the Google App Engine

Following info provided by Maurizio Taverna...

We have (with some provisos) successfully deployed a version of the quickstart_wicket_restful_jdo on GAE.
Below the information collected :

1. DataNucleusApplicationComponents.java
61:persistenceManagerFactory = JDOHelper.getPersistenceManagerFactory(props);
replaced with :
61:persistenceManagerFactory = JDOHelper.getPersistenceManagerFactory("transactions-optional");

See official Google documentation :
https://developers.google.com/appengine/docs/java/datastore/jdo/overview-dn2#Getting_a_PersistenceManager_Instance

66:createSchema(props, classesToBePersisted);
replace with :
// 66:createSchema(props, classesToBePersisted);
This feature is for RDBMS, it raise exception using DN Google implementation.

2. PersistenceSession.java
894:if (adapter.getVersion() == null)

{ 895: throw new ObjectPersistenceException("Object to be ... " + adapter); 896:}

replaced with:
894://if (adapter.getVersion() == null)

{ 895:// throw new ObjectPersistenceException("Object to be ... " + adapter); 896://}

We could not understand why the version is null, during the fixture installation ( removeAllToDosForCurrentUser ).

3. jdoconfig.xml
The Google App Engine keep the Jdo configuration in /WEB-INF/classes/META-INF/jdoconfig.xml.
We changed :

<property name="datanucleus.appengine.autoCreateDatastoreTxns" value="false"/>

This is a workaround, more information available here:
https://developers.google.com/appengine/docs/java/datastore/jdo/overview-dn2#Disabling_Transactions_and_Porting_Existing_JDO_Apps

With the changes above, the quickstart_wicket_restful_jdo is possible install the fixtures and list the items,
but there are still errors accessing to an item.
At https://docs.google.com/file/d/0B-Ekm92XLvTAcGxHNTJyRDA3bkk/edit?usp=sharing please find the zip of the project, including the ant build script , a live version is available here: http://isis-gae.appspot.com/.
In order to run the example you need to install the GAE SDK and point the appengine.sdk property
to the GAE SDK installation path.
In addition please check in

{gae.sdk}lib/tools/orm contains the datanucleos 3.1.1 jars. If not remove all the jar files (in default installation I found datanucleus 1.5 jars) and replace with jars available in {gae.sdk}

/lib/opt/user/datanucleus/v2.

Stack trace obtained when trying to access object:

Unexpected RuntimeException

Last cause: null
WicketMessage: Can't instantiate page using constructor 'public org.apache.isis.viewer.wicket.ui.pages.entity.EntityPage(org.apache.wicket.request.mapper.parameter.PageParameters)' and argument 'objectOid=[TODO:L_1003], pageType=[ENTITY], pageTitle=[Write blog post]'. Might be it doesn't exist, may be it is not visible (public).

Stacktrace

Root cause:

java.lang.NullPointerException
at com.google.appengine.datanucleus.EntityUtils.idToInternalKey(EntityUtils.java:204)
at com.google.appengine.datanucleus.DatastoreIdentityKeyTranslator.getKey(DatastoreIdentityKeyTranslator.java:32)
at org.datanucleus.ObjectManagerImpl.newObjectId(ObjectManagerImpl.java:3439)
at org.datanucleus.api.jdo.JDOPersistenceManager.newObjectIdInstance(JDOPersistenceManager.java:1618)
at org.datanucleus.api.jdo.JDOPersistenceManager.getObjectById(JDOPersistenceManager.java:1740)
at org.apache.isis.objectstore.jdo.datanucleus.DataNucleusObjectStore.loadPojo(DataNucleusObjectStore.java:380)
at org.apache.isis.objectstore.jdo.datanucleus.persistence.adaptermanager.DataNucleusPojoRecreator.recreatePojo(DataNucleusPojoRecreator.java:38)
at org.apache.isis.core.runtime.persistence.adaptermanager.AdapterManagerDefault.adapterFor(AdapterManagerDefault.java:300)
at org.apache.isis.viewer.wicket.model.mementos.ObjectAdapterMemento$Type$2.recreateAdapter(ObjectAdapterMemento.java:104)
at org.apache.isis.viewer.wicket.model.mementos.ObjectAdapterMemento$Type.getAdapter(ObjectAdapterMemento.java:170)
at org.apache.isis.viewer.wicket.model.mementos.ObjectAdapterMemento.getObjectAdapter(ObjectAdapterMemento.java:288)
at org.apache.isis.viewer.wicket.model.models.EntityModel.load(EntityModel.java:193)
at org.apache.isis.viewer.wicket.model.models.EntityModel.load(EntityModel.java:202)
at org.apache.isis.viewer.wicket.model.models.EntityModel.load(EntityModel.java:52)
at org.apache.wicket.model.LoadableDetachableModel.getObject(LoadableDetachableModel.java:121)
at org.apache.isis.viewer.wicket.ui.components.entity.EntityComponentFactoryAbstract.appliesTo(EntityComponentFactoryAbstract.java:55)
at org.apache.isis.viewer.wicket.ui.ComponentFactoryAbstract.appliesTo(ComponentFactoryAbstract.java:61)
at org.apache.isis.viewer.wicket.viewer.registries.components.ComponentFactoryRegistryDefault.findComponentFactories(ComponentFactoryRegistryDefault.java:136)
at org.apache.isis.viewer.wicket.viewer.registries.components.ComponentFactoryRegistryDefault.findComponentFactory(ComponentFactoryRegistryDefault.java:153)
at org.apache.isis.viewer.wicket.viewer.registries.components.ComponentFactoryRegistryDefault.findComponentFactoryElseFailFast(ComponentFactoryRegistryDefault.java:159)
at org.apache.isis.viewer.wicket.viewer.registries.components.ComponentFactoryRegistryDefault.createComponent(ComponentFactoryRegistryDefault.java:119)
at org.apache.isis.viewer.wicket.viewer.registries.components.ComponentFactoryRegistryDefault.addOrReplaceComponent(ComponentFactoryRegistryDefault.java:105)
at org.apache.isis.viewer.wicket.ui.pages.PageAbstract.addComponent(PageAbstract.java:201)
at org.apache.isis.viewer.wicket.ui.pages.PageAbstract.addChildComponents(PageAbstract.java:196)
at org.apache.isis.viewer.wicket.ui.pages.entity.EntityPage.<init>(EntityPage.java:50)
at java.lang.reflect.Constructor.newInstance(Constructor.java:33)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:170)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:98)
at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:137)
at org.apache.wicket.core.request.handler.PageProvider.resolvePageInstance(PageProvider.java:278)
at org.apache.wicket.core.request.handler.PageProvider.getPageInstance(PageProvider.java:166)
at org.apache.wicket.request.handler.render.PageRenderer.getPage(PageRenderer.java:78)
at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:94)
at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:196)
at org.apache.wicket.core.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:165)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:830)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:253)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:210)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:281)
at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:245)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449)
at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)
at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383)
at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)
at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:454)
at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:461)
at com.google.tracing.TraceContext.runInContext(TraceContext.java:703)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:338)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:330)
at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:458)
at java.lang.Thread.run(Thread.java:679)

Complete stack:

org.apache.wicket.WicketRuntimeException: Can't instantiate page using constructor 'public org.apache.isis.viewer.wicket.ui.pages.entity.EntityPage(org.apache.wicket.request.mapper.parameter.PageParameters)' and argument 'objectOid=[TODO:L_1003], pageType=[ENTITY], pageTitle=[Write blog post]'. Might be it doesn't exist, may be it is not visible (public).
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:193)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:98)
at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:137)
at org.apache.wicket.core.request.handler.PageProvider.resolvePageInstance(PageProvider.java:278)
at org.apache.wicket.core.request.handler.PageProvider.getPageInstance(PageProvider.java:166)
at org.apache.wicket.request.handler.render.PageRenderer.getPage(PageRenderer.java:78)
at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:94)
at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:196)
at org.apache.wicket.core.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:165)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:830)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:253)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:210)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:281)
at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)

java.lang.reflect.InvocationTargetException
at com.google.appengine.runtime.Request.process-d3177901ba10f473(Request.java)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:33)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:170)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:98)
at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:137)
at org.apache.wicket.core.request.handler.PageProvider.resolvePageInstance(PageProvider.java:278)
at org.apache.wicket.core.request.handler.PageProvider.getPageInstance(PageProvider.java:166)
at org.apache.wicket.request.handler.render.PageRenderer.getPage(PageRenderer.java:78)
at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:94)
at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:196)
at org.apache.wicket.core.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:165)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:830)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:253)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:210)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:281)
at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)