See how maven works inside – remote debugging plugins

Who uses maven as I do for a long time, knows that sometimes things does not go as expected. So it’s necessary to look at the ultimate documentation: the source code! In this post I’ll show how to debug a maven plugin using Eclipse’s remote debugger. I’ve chosen for this example the maven-clean-plugin.

Ok, let’s start. First create a simple sample project:

    mvn archetype:create -DgroupId=com.wordpress -DartifactId=maven-debug

In the folder maven-debug, edit the pom.xml and add the dependency of the plugin. This will serve as an “anchor” to bring all the sources needed to debug.

<dependency>
       <groupId>org.apache.maven.plugins</groupId>
       <artifactId>maven-clean-plugin</artifactId>
       <version>2.1.1</version>
       <scope>provided</scope>
</dependency>

Note the scope “provided”, meaning that the dependency will be given to the project by someone and it should not make to the final package. It shouldn’t matter, anyway, since this is a dependency that will be removed later, it’s just for debug purposes.

It’s important to know what version of the plugin your project is using. When in doubt, run “mvn -X clean” and note lines like:

  [DEBUG] Retrieving parent-POM: org.apache.maven.plugins:maven-plugins::3 for project:
           null:maven-clean-plugin:maven-plugin:2.1.1 from the repository.

Now generate the project in eclipse:

   mvn -Declipse.downloadSources=true eclipse:eclipse

Open eclipse, go to File -> Import -> Existing Projects into Workspace and select the root directory of the project. After that go to menu
“Run –> Open debug dialog” and under “Remote java application” create a new profile to debug our project:

Using the eclipse search facilities, search for a class which name ends with “Mojo” (Maven Old Java Object) and place a breakpoint in the “execute” method. In the case of the clean plugin, this class is called CleanMojo

To debug, first enable debug on maven in the command line (linux shown here)

MAVEN_OPTS="-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000";
export MAVEN_OPTS

and then do a “mvn clean”; the process will halt. Start the debugger in eclipse, it will hit the breakpoint.

Congratulations! Now you can know exactly what’s going on!

Watching live soccer in Gentoo – part 1 – SopCast

The portal myp2p.eu is a very interesting site where you can choose among several live sports and watching ‘em live, with very good quality. The matches can be seen with a myriad of softwares, among them: windows media, real audio, sopcast, tvants. In this post I’ll focus on SopCast.

Gentoo portage does not have an ebuild for sopcast (yet), but meanwhile there is a sopcast ebuild on gentoo bugzilla. To install it, download the file http://bugs.gentoo.org/attachment.cgi?id=137461 and save it to /usr/portage/media-tv/sopcast-1.1.1.ebuild.

Edit sopcast-1.1.1.ebuild and change the URL from

   SRC_URI="http://download.sopcast.com/download/${MY_P}.tgz"

to

   SRC_URI="http://download.sopcast.cn/download/${MY_P}.tgz"

As the packages are masked, first we have unmask them:

    echo "=media-tv/sopcast-1.1.1" >> /etc/portage/package.keywords

Before emerging, go to the ebuild dir and generate the manifest:

    ebuild  sopcast-1.1.1.ebuild digest

and finally

    emerge sopcast

Now the fun bergins!

Under myp2p.eu/competition.php?competitionid=∂=sports&discipline=football choose the match you want to see, copy the adress (that beggins with the “protocol” sop://) and run the command:

   sp-sc sop://broker1.sopcast.com:3912/6001 1234 5678

that opens the stream from local port “1234″ to player port “5678″. Player port is where you will watch the video. So, to watch with Xine (my favorite), run:

   xine http://localhost:5678

and that’s it! Nice game!