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NOTICE There is a new plugin (archetypes and eclipse integration), a fresh start that correctly support multi-module projects, it is not version-bounded with GWT, support multiples GWT versions and other fixes, improvements and best practices. This plugin is now considered the legacy GWT maven plugin (aka mojo GWT maven plugin) and the new one is considered the new generation GWT maven plugin (aka tbroyer GWT maven plugin). The legacy maven plugin is still supported but it is strongly encouraged to use the new one for new projects.

Productivity tip for multi-project setup


Consider the following project setup

  • api (jar) - GWT library
  • gui (war) - GWT gui with endpoint that uses the library.

    With this layout, any change to the api (gwt library) must be repackaged as a JAR and the hosted mode must be restarted to see the change in the hosted browser.

    The following tip explains how to use the build-helper-maven-plugin to improve productivity and hack the multi-project wall between modules.

Build helper

Build-helper-maven-plugin allow you to setup additional source folders for your project. The idea here is to declare the api source folder to make it "visible" from the war project / hosted mode browser.

If you add a source path with the build-helper-maven-plugin directly in the gui's pom you will possibly have problems because of 2 issues.

  • At least my IDE (Netbeans) cannot have two open projects that share the same source path. The api module will loose its src/java in the user interface, and the gui will get one ekstra "generated sources" path, this is quite annoying.
  • Because there is no guarantee on how the developer will checkout the code, the gui's pom cannot guess where the api's src/main/java is on the disk.


The solution to those two issues is to create a profile in your pom which you'd only activate when you run the gwt:run target:


You can then test in development mode and edit files in multible projects by running:

mvn gwt:run -Pdev

In Netbeans it is possible to save such a run target in the user interface.