Maven multi-module web application (Hot swap)

Question

I have a multi module web application.

The structure is:

Parent
|
| - - Child 1
| - - Child 2
| - - Web

And the web project depends on the two child modules

When using my IDE to build my project I was used to the IDE building the classes in the WEB-INF/classes folder. This was nice as the web server noticed the new classes and either restarted or hot deployed these files. With maven it seems that I have to package the whole thing from scratch every time.

I would like to find a way in maven such that i can avoid running mvn:clean mvn:install mvn:war:inplace. Instead I would like a mvn:comile, and then the stuff just there.

I hope you understand what I mean. Testing the web app is extremely slow when you always have to build all the project jars and run som war command before things are updated.

The web apps pom:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

   <modelVersion>4.0.0</modelVersion>

   <parent>
       ...
   </parent>

   <artifactId>web</artifactId>
   <packaging>war</packaging>

   <dependencies>
      <dependency>
         <groupId>bla.bla.bla</groupId>
         <artifactId>bla_child1</artifactId>
         <version>1.0-SNAPSHOT</version>
      </dependency>
      <dependency>
         <groupId>bla.bla.bla</groupId>
         <artifactId>bla_child2</artifactId>
         <version>1.0-SNAPSHOT</version>
      </dependency>
   </dependencies>

   <build>
      <plugins>
         <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>2.4</version>
         </plugin>
         <plugin>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-maven-plugin</artifactId>
            <version>9.0.4.v20130625</version>
            <configuration>
               <scanIntervalSeconds>30</scanIntervalSeconds>
               <webApp>
                  <contextPath>/blabla</contextPath>
               </webApp>
            </configuration>
         </plugin>
      </plugins>
   </build>
</project>

Answer 1

A possible solution to your problem could be to build a skinny war with the maven-war-plugin (or at least exclude child1 and child2 if you have other dependencies as well) and add the target/classes folders of the child-projects to your classpath. This could be done with the Build Helper Maven Plugin's add-resource goal.

Disclaimer: I didn't try this myself but in theory it could work :)

Answer 2

This is my own temporary answer to this problem.

It would be nice if it could be done with maven, but I haven't been able to find a solution. Therefore I have bound an ant target to the compile phase of the web module.

This is probably not a solution that can be used anywhere, but it works in my case.

web/pom.xml:

          <plugin>
            <artifactId>maven-antrun-plugin</artifactId>
            <version>1.7</version>
            <executions>
               <execution>
                  <id>copy-modules</id>
                  <phase>compile</phase>
                  <configuration>
                     <target>
                        <delete dir="${project.basedir}\src\main\webapp\WEB-INF\classes"/>
                        <copy todir="${project.basedir}\src\main\webapp\WEB-INF\classes">
                           <fileset dir="${main.basedir}\modules\child-1\target\classes">
                              <include name="**/*.class"/>
                              <include name="**/*.xml"/>
                           </fileset>
                           <fileset dir="${main.basedir}\modules\child-2\target\classes">
                              <include name="**/*.class"/>
                              <include name="**/*.xml"/>
                           </fileset>
                        </copy>
                     </target>
                  </configuration>
                  <goals>
                     <goal>run</goal>
                  </goals>
               </execution>
            </executions>
         </plugin>

Now the jetty sees everytime I do a compile, which is much faster than install, war and the stuff that was needed before.