Programmer: Lifelong Learning: Using Maven with Google App Engine

Maven is very good at managing the project's dependencies, so I also choose maven when develop GAE project.

Google Eclipse plugin doesn't support GAE maven development very well: we can't use Google Eclipse plugin to directly run, debug the app or deploy it to app engine.

To run the app in local GAE server:
cd ${mypp}\${mypp-ear}
mvn -f ..\pom.xml clean install && mvn appengine:devserver

To debug the app: add the following in pom.xml:

<plugins>
  <plugin>
    <groupId>com.google.appengine</groupId>
    <artifactId>appengine-maven-plugin</artifactId>
    <configuration>
      <jvmFlags>
        <jvmFlag>-Xdebug</jvmFlag>
        <jvmFlag>-agentlib:jdwp=transport=dt_socket,address=9999,server=y,suspend=n</jvmFlag>
      </jvmFlags>
      <disableUpdateCheck>true</disableUpdateCheck>
    </configuration>
  </plugin>
</plugins>

Start the local GAE server, then create a remote application to connect to localhost:9999. Now we can debug the GAE maven application in eclipse.

Change Application Id

For some reason, we may want to deploy the same application with multiple application id. - We may use GAE as backbone application, our client application maybe mobile app or even google blogger(as google doesn't allow to put ads in GAE app, we may use google bloger as the front side which talks with GAE server to do real task.).

When our application is getting popular, and exceeds the free quota. We may want to duplicate our applition to deploy under another application id.

If we are using maven to build and deploy, we need change the application id: ${mypp}\${mypp-ear}\src\main\application\META-INF\appengine-application.xml.

Then deploy it to the new application id:

cd ${mypp}\${mypp-ear}

mvn -f ..\pom.xml clean install && mvn appengine:update

Resources

GAE Using Apache Maven

Using Maven with Google App Engine

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