The following exemple define an environment variable and a datasource for tomcat and jetty:

For tomcat : add to your “context.xml” :

<Environment name="yourapp.basedir"
	value="/path/to/project/target/app"
	type="java.lang.String" override="false" />

<Resource auth="Container"
	driverClassName="org.apache.derby.jdbc.EmbeddedDriver"
	name="jdbc/yourDatasource" type="javax.sql.DataSource"
	url="jdbc:derby:test;create=true" username="APP" password="APP"
	maxActive="10" maxIdle="4"  />

For jetty embedded in gwt : create a new file jetty-web.xml, in your WEB-INF :

<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd">
<Configure id="webAppCtx" class="org.mortbay.jetty.webapp.WebAppContext">
	<New id="yourapp.basedir" class="org.mortbay.jetty.plus.naming.EnvEntry">
		<Arg>java:comp/env/yourapp.basedir</Arg>
		<Arg type="java.lang.String">/path/to/project/target/app</Arg>
		<Arg type="boolean">true</Arg>
	</New>
	<New id="yourDatasource" class="org.mortbay.jetty.plus.naming.Resource">
		<Arg>java:comp/env/jdbc/yourDatasource</Arg>
		<Arg>
			<New class="org.apache.derby.jdbc.EmbeddedDataSource">
				<Set name="DatabaseName">test</Set>
				<Set name="createDatabase">create</Set>
			</New>
		</Arg>
	</New>
</Configure>

For the datasource, don’t forget to add to your web.xml :

 <resource-ref>
    <description>DB Connection</description>
    <res-ref-name>jdbc/yourDatasource</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
  </resource-ref>

To access it from your java server class (ServletContextListener / Servlet …) :

try {
  Context initCtx = new InitialContext();

  // to access your datasource
  Datasource dataSource = (DataSource)context.lookup("java:comp/env/yourDatasource");
  // get a connection and use it ....

  // to access the environment entry list
  NamingEnumeration<Binding> bindingsEnum = initCtx.listBindings("java:comp/env");
  while (bindingsEnum.hasMore()) {
    Binding binding = bindingsEnum.next();
    System.out.printf("%s = %s\n", binding.getName(), binding.getObject().toString());
    // memorize this settings parameters somewhere ...
  }

 } catch (NamingException e) {
   // ... handle it
 }

Now, back to gwt, maven and eclipse :

Add to your pom.xml  :

<properties>
  <gwtVersion>2.4.0</gwtVersion>
  <webappDirectory>${project.build.directory}/${project.build.finalName}
  </webappDirectory>
</properties>

<dependencies>
  <!-- gwt core -->
  <dependency>
    <groupId>com.google.gwt</groupId>
    <artifactId>gwt-servlet</artifactId>
    <version>${gwtVersion}</version>
  </dependency>
  <dependency>
    <groupId>com.google.gwt</groupId>
    <artifactId>gwt-user</artifactId>
    <version>${gwtVersion}</version>
    <scope>provided</scope>
  </dependency>
  <!-- needed by for jndi access (jetty embedded container) -->
  <dependency>
    <groupId>org.mortbay.jetty</groupId>
    <artifactId>jetty-plus</artifactId>
    <version>6.1.11</version>
    <scope>provided</scope>
  </dependency>
  <dependency>
    <groupId>org.mortbay.jetty</groupId>
    <artifactId>jetty-naming</artifactId>
    <version>6.1.11</version>
    <scope>provided</scope>
  </dependency>
  <!-- only needed for datasource testing -->
  <dependency>
    <groupId>org.apache.derby</groupId>
    <artifactId>derbyclient</artifactId>
    <version>10.6.1.0</version>
  </dependency>
  <dependency>
    <groupId>org.apache.derby</groupId>
    <artifactId>derby</artifactId>
    <version>10.6.1.0</version>
  </dependency>
</dependencies>

<build>
  <finalName>yourAppContext</finalName>
  <outputDirectory>${webappDirectory}/WEB-INF/classes</outputDirectory>

  <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>gwt-maven-plugin</artifactId>
    <version>${gwtVersion}</version>
    <executions>
      <execution>
        <goals>
          <goal>compile</goal>
        </goals>
      </execution>
    </executions>
    <configuration>
      <extraJvmArgs>-Xmx512M -XX:MaxPermSize=196m -Xss1024k -Djava.naming.factory.initial=org.mortbay.naming.InitialContextFactory
      </extraJvmArgs>
      <runTarget>YourApplication.html</runTarget>
      <hostedWebapp>${webappDirectory}</hostedWebapp>
    </configuration>
  </plugin>

  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-war-plugin</artifactId>
    <version>2.1.1</version>
    <executions>
      <execution>
        <phase>compile</phase>
        <goals>
          <goal>exploded</goal>
        </goals>
      </execution>
    </executions>
    <configuration>
      <webappDirectory>${webappDirectory}</webappDirectory>
    </configuration>
  </plugin>
</build>

To explain, the two jetty dependencies are not included in the gwt-dev core (the debugging tool with the embedded jetty), they are “provided” scope because they are only used during development / testing (“test” scope does not works with gwt-maven plugin). The last two derby dependencies  are only here for the datasource example.

For accessing jdni resources, you then need to define a java environment variable :

-Djava.naming.factory.initial=org.mortbay.naming.InitialContextFactory

If you use Google plugin for Eclipse : edit the run / debug preferences of your project :

If you use the maven gwt plugin :

mvn gwt:run

To compile and install the final war plugin :

mvn clean install

Once the gwt application tested and compiled : If you works with apache tomcat under eclipse, I highly recommend the tomcat plugin (with its DevClassLoader for hot code replace) : http://www.eclipsetotale.com/tomcatPlugin.html

All works with google 2.5.0-rc1 too

To conclude, you can develop with gwt as though you worked on your prefered servlet container like tomcat / jetty … Without hack , gwt rpc servlets can now uses jndi resources like datasources, environment variables… A simple “war” project could be used for debugging or delivering your web application version.