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The Java EE 5 Tutorial

Debugging Java EE Applications

This section describes how to determine what is causing an error in your application deployment or execution.

Using the Server Log

One way to debug applications is to look at the server log in domain-dir/logs/server.log. The log contains output from the Application Server and your applications. You can log messages from any Java class in your application with System.out.println and the Java Logging APIs (documented at http://java.sun.com/javase/6/docs/technotes/guides/logging/index.html) and from web components with the ServletContext.log method.

If you start the Application Server with the --verbose flag, all logging and debugging output will appear on the terminal window or command prompt and the server log. If you start the Application Server in the background, debugging information is only available in the log. You can view the server log with a text editor or with the Admin Console log viewer.

    To use the log viewer:

  1. Select the Application Server node.

  2. Select the Logging tab.

  3. Click the Open Log Viewer button. The log viewer will open and display the last 40 entries.

    If you wish to display other entries:

  1. Click the Modify Search button.

  2. Specify any constraints on the entries you want to see.

  3. Click the Search button at the bottom of the log viewer.

Using a Debugger

The Application Server supports the Java Platform Debugger Architecture (JPDA). With JPDA, you can configure the Application Server to communicate debugging information using a socket.

    To debug an application using a debugger:

  1. Enable debugging in the Application Server using the Admin Console:

    1. Select the Application Server node.

    2. Select the JVM Settings tab. The default debug options are set to:


      -Xdebug -Xrunjdwp:transport=dt_socket,server=y, suspend=n,address=9009

      As you can see, the default debugger socket port is 9009. You can change it to a port not in use by the Application Server or another service.

    3. Check the Enabled box of the Debug field.

    4. Click the Save button.

  2. Stop the Application Server and then restart it.