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CapeDwarf Frequently Asked Questions

CapeDwarf Frequently Asked Questions

Here’s a list of questions frequently posed by our users.

1. I’m getting a NullPointerException in NamespaceManager.get()

CapeDwarf bundles the original appengine-api jar file in %CAPEDWARF_HOME%/modules/com/google/appengine/main. Legal restrictions don’t allow us to bundle a pre-modified jar with CapeDwarf, which is what CapeDwarf needs in order to work correctly. If you are bundling the jar in your WAR (as is usually the case), CapeDwarf will automatically modify the jar in your WAR. However, if you are not including the jar in your WAR, CapeDwarf will automatically use the jar in the modules dir. In order for it to work properly, you must modify the JAR yourself, either by manually running %CAPEDWARF_HOME%/bin/capedwarf-bytecode.sh or capedwarf-bytecode.bat; or by running CapeDwarf with capedwarf.sh or capedwarf.bat.

If you do not include the appengine jar in your war and you also do not run capedwarf-bytecode.sh and you start CapeDwarf with standalone.sh instead of capedwarf.sh, you will get errors similar to the following:

2014-02-18 15:38:30,561 ERROR [io.undertow.request] (default task-14) UT005023: Exception handling request to /index: java.lang.NullPointerException
at com.google.appengine.api.NamespaceManager.get(NamespaceManager.java:101) [appengine-api-1.0-sdk-1.8.8.jar:1384479771]
at com.google.appengine.api.search.SearchServiceImpl.getAppNamespace(SearchServiceImpl.java:121) [appengine-api-1.0-sdk-1.8.8.jar:]
at com.google.appengine.api.search.SearchServiceImpl.<init>(SearchServiceImpl.java:26) [appengine-api-1.0-sdk-1.8.8.jar:]
at com.google.appengine.api.search.SearchServiceFactoryImpl.getSearchService(SearchServiceFactoryImpl.java:36) [appengine-api-1.0-sdk-1.8.8.jar:]
at com.google.appengine.api.search.SearchServiceFactory.getSearchService(SearchServiceFactory.java:52) [appengine-api-1.0-sdk-1.8.8.jar:]
at com.google.appengine.api.search.SearchServiceFactory.getSearchService(SearchServiceFactory.java:61) [appengine-api-1.0-sdk-1.8.8.jar:]
at org.jboss.capedwarf.todolist.dao.AbstractDAO.<init>(AbstractDAO.java:41) [classes:]
at org.jboss.capedwarf.todolist.dao.TasksDAO.<init>(TasksDAO.java:44) [classes:]

The key thing that signals that you are using the original appengine-sdk.jar and not the modified version, is the presence of SearchServiceImpl in the stack trace. If the modified jar was being used, the search service implementation class would be CapedwarfSearchService. All other service implementations in CapeDwarf also begin with Capedwarf and do not end with Impl.

2. I get a 404 Not Found when I try to access my servlets

Our handling of static-files in appengine-web.xml is not 100% correct. If your appengine-web.xml includes all paths as static files, none of your servlets will be available. To work around this, remove the following line from appengine-web.xml:

<static-files>
    <include path="**" />
</static-files>
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