2. You'll receive an HTTP 404 error message.
3. Open your App Engine Administration Console. Click the Logs link in the
left navigation panel.
4. Change the Minimum Severity to Debug.
5. Open the most recent Warning message by clicking the plus (+) sign to the
left of the message. The subject should be No handlers matched this URL.
6. Analyze the message. You'll notice that the URL that you tried to access in
the first step is what caused this warning in the application. For example, if
this were a real situation you might have inadvertently excluded an entry in
your web.xml file.
7. Expand the Options link to the right of the Minimum Severity drop-down. In
the Filter text field enter URL , and then click View. Experiment with the
other options to show messages before or after certain time periods.
This was a quick example of how to analyze the Google App Engine application log for
warning messages. In this case you caused a 404 Not Found error by attempting to access
an invalid path.
Downloading Log Files
You can download the log files from your application for more detailed analysis. To
download the logs to your local computer, use the request_logs action of your appcfg
utility, which came with the App Engine SDK. Listing 9-2 shows the command syntax
for Mac OS X. Listing 9-3 shows the command syntax for Windows.
Listing 9-2. Download log files on Mac OS X
appengine-java-sdk/bin/appcfg.sh request_logs myapp\war mylog.txt
Listing 9-3. Download log files on Windows
appengine-java-sdk\bin\appcfg.cmd request_logs myapp\war mylog.txt