Why is Tomcat unable to show the actual stack trace?

Question

Using GWT, I have deployed my server into Tomcat. This works fine, but when GWT throws an exception, a Popup shows the client the

Answer 1

It's a bit difficult to find all the information in the GWT docs, which you need to setup de-obfuscated logging, so here's the short version:

In your module file (.gwt.xml), add:

On the client side, use something like

import java.util.logging.Logger;

private static Logger rootLogger = Logger.getLogger("");
...
rootLogger.log(Level.SEVERE, "My message", e);

You don't have to create a RemoteLoggingServiceAsync instance on the client side - it's used automatically by the logger, because we specified .

On the server side, configure the RemoteLoggingServiceImpl. You will have to tell it, where it finds the symbolMaps, which will be generated when compiling with the GWT compiler argument -extra /path/to/myExtraDir. I personally use the approach to override RemoteLoggingServiceImpl, to allow specifying the directory from web.xml's s ^[*]

package mypackage.server;

public class ConfigurableRemoteLoggingServiceImpl extends RemoteLoggingServiceImpl {

  @Override
  public void init(final ServletConfig config) throws ServletException {
    super.init(config);

    final String symbolMapsDirectory = 
        config.getInitParameter("symbolMapsDirectory");
    setSymbolMapsDirectory(symbolMapsDirectory);
  }
}

In web.xml, register it like

    remoteLogging
    mypackage.server.ConfigurableRemoteLoggingServiceImpl

  
    symbolMapsDirectory
    /path/to/myExtraDir/mymodulename/symbolMaps
  


    remoteLogging
    /mymodulename/remote_logging

Replace /path/to/myExtraDir, mymodulename and mypackage with your own values, and don't forget to call the GWT compiler with the -extra argument (Note that you you don't have to use -style PRETTY or DETAILED, it also works with OBF). Keep all generated symbolMaps: Without them, deobfuscation will not work. As every new version gets a unique name automatically, you can collect them all in a safe central place when building.

^{[*] And I really, really wonder, why RemoteLoggingServiceImpl doesn't implement that itself!}