Matt RaibleMatt Raible is a Web Architecture Consultant specializing in open source frameworks.

10+ YEARS


Over 10 years ago, I wrote my first blog post. Since then, I've authored books, had kids, traveled the world, found Trish and blogged about it all.

Running Hosted Mode in GWT Libraries (when using Maven)

Earlier this year, I wrote about Modularizing GWT Applications with GWT-Maven. Fast forward 8 months and I'm still working with GWT and using this same technique. However, this time I'm working with the Maven GWT Plugin from Codehaus. In my last post, I wrote:

The results of modularizing your application are beneficial (shared code) and detrimental (you have to mvn install gwt-core whenever you make changes in shared classes). If you know of a way to configure the gwt-maven plugin to read sources from both gwt-core and gwt-webapp in hosted mode, I'd love to hear about it.

The good news is I found a solution for this, using the Builder Helper Maven Plugin. The GWT Maven Plugin's Productivity tip for multi-project setup has more information on how to configure this (note: we use IntelliJ and Eclipse on my project and did not need to configure this in a profile).

All was fine and dandy with this configuration until I wanted to be able to run hosted mode to develop/test everything in my library before including it in my main project. Luckily, you can still run mvn gwt:run on a JAR project. However, when you configure your pom.xml so sources are included in your JAR, you run into an issue: your *.java files will be copied to war/WEB-INF/classes and hosted mode will use these files as source rather than the ones you're editing in src/main/java.

To solve this, I changed my pom.xml to do two things:

  • Only copy resources right before packaging (in the test phase).
  • When packaging is complete, delete the *.java files from war/WEB-INF/classes (using Ant).

Below is the XML I used to make this possible. Please let me know if you have a way to simplify this configuration.

<plugin>
    <artifactId>maven-resources-plugin</artifactId>
    <version>2.4.1</version>
    <executions>
        <execution>
            <phase>test</phase>
            <goals>
                <goal>copy-resources</goal>
            </goals>
            <configuration>
                <outputDirectory>${project.build.outputDirectory}</outputDirectory>
                <resources>
                    <resource>
                        <directory>src/main/java</directory>
                    </resource>
                    <resource>
                        <directory>src/main/resources</directory>
                    </resource>
                </resources>
            </configuration>
        </execution>
    </executions>
</plugin>
<plugin>
    <artifactId>maven-antrun-plugin</artifactId>
    <version>1.3</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>run</goal>
            </goals>
            <configuration>
                <tasks>
                    <delete>
                        <fileset dir="${project.build.outputDirectory}" includes="**/*.java"/>
                    </delete>
                </tasks>
            </configuration>
        </execution>
    </executions>
</plugin>

This solution seems to work pretty well. As far as developing your library in hosted mode, you'll need to configure two *.gwt.xml files, one that doesn't have an <entry-point> defined and one that does. Configure the one with the entry point as the <module> in your gwt-maven-plugin configuration.

As a side note, I found a few issues with the 1.1 version of the Maven GWT Archetype. Below are the steps I used to fix these issues and upgrade to GWT 1.7.0 (I realize 1.7.1 is out, but gwt-dev-1.7.1-mac.jar doesn't exist in Maven central).

First, create a new project by running the following from the command line:

mvn archetype:generate \
  -DarchetypeGroupId=org.codehaus.mojo \
  -DarchetypeArtifactId=gwt-maven-plugin \
  -DarchetypeVersion=1.1 \
  -DgroupId=com.yourcompany \
  -DartifactId=gwt-project -Dversion=1.0-SNAPSHOT -B

After creating the project, you'll need to modify the pom.xml as follows:

  1. Change the gwt-maven-plugin's version to 1.1.
  2. Change the ${gwtVersion} property to 1.7.0.
  3. Add <runTarget>Application.html</runTarget> to the <configuration> element of the plugin.
  4. Move Application.html and web.xml so they're under the "war" directory.
  5. Update Application.html to prepend the GWT module name in the <script> tag.

I hope these instructions help you create modular GWT projects with Maven. This setup is working great on my current project.

Posted in Java at Nov 03 2009, 09:37:07 AM MST 3 Comments
Comments:

[Trackback] This post was mentioned on Twitter by mraible: Blog entry on how to run Hosted Mode in GWT Libraries (when using Maven): http://bit.ly/2r0U7D

Posted by uberVU - social comments on November 03, 2009 at 03:26 PM MST #

Have you ported to GWT 2.0 yet?

Posted by Ken on January 05, 2010 at 11:48 PM MST #

@Ken - Yes, we upgraded to GWT 2.0 shortly after I wrote this post.

Posted by Matt Raible on January 05, 2010 at 11:50 PM MST #

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