Migrating to the catkinized version of KnowRob

Starting from ROS hydro/indigo, KnowRob has switched to the catkin buildsystem and the 'new' rosjava. This page explains the steps that are needed for transforming packages that have been built for the old version to the new KnowRob.

As a first step, you can use the 'catkinize' scripts that generate something like a valid catkin package from your rosbuild packages. The following manual steps are then

• Clean up the package.xml, e.g. setting the author and maintainer names and emails. Please check for package names that may have changed.
• Update the CMakeLists.txt, also update changed package names. Remove all rosbuild and old rosjava statements, e.g. for generating .owl from .owl.in files.

Rosjava uses the gradle builsystem that is at the moment (07/2014) only loosely integrated with catkin. Therefore, some things like dependencies need to be specified multiple times. Make sure to read the official documentation in the ROS wiki as well as the rosjava_core Sphinx documentation carefully to understand the main concepts first.

There is a one-to-many relation between catkin packages and rosjava sub-projects as described here. This structure has been adopted in KnowRob: In each KnowRob package that contains Java code, there is a folder with the same name containing the respective rosjava subproject. In case the package requires custom messages, there is another subfolder with the name of the message package. For example, the json_prolog package (depending on the service defined in json_prolog_msgs) looks like this:

  json_prolog_msgs        <-- catkin package
    |- srv
    |- package.xml
    \- ...
    
  json_prolog             <-- catkin package
    |- gradle             <-- gradle wrapper needed for compiling the rosjava code
    |- json_prolog        <-- rosjava subproject
    |     |- src        
    |     \- build.gradle
    |
    |- json_prolog_msgs   <-- rosjava subproject for the custom service definitions
    |     \- build.gradle
    |
    |- build.gradle
    |- gradlew
    |- package.xml
    \- ...

Rosjava is now based on Maven that 'magically' maintains jar files for dependendies. The following snippet explains how dependencies are specified in the build.gradle of the respective subproject:

  dependencies {
    /* Dependency on a rosjava project in the same catkin package */ 
    compile project(':json_prolog_msgs')
    
    /* Dependency on a rosjava project in another catkin package */
    compile 'org.ros.rosjava_core:rosjava:[0.1,)'

    /* Dependency on external jar files (will be downloaded from mavencentral */
    compile 'net.sf.json-lib:json-lib:2.4:jdk15'
  }

You can use the service at http://gradleplease.appspot.com/ to generate the lines to be put into the build.gradle

In the 'normal' case, the classpath for a rosjava node only needs to contain the dependencies of the package the node is located in. With json_prolog, we however have a special case: It serves as launcher for other packages (e.g. knowrob_vis) that may also contain Java code. We therefore need to add the Java dependencies of json_prolog itself AND the dependencies of the packages to be launched to the classpath.

This is not easy with the existing tools (since the exporting packages are not by themselves catkin packages), so we had to find another solution: During compilation, gradle creates a file 'classpath.txt' with the dependencies of the respective package. At runtime, rosprolog and json_prolog collect these files and assemble the overall classpath from them. You need to add the following statement to the build.gradle of the respective (exporting) subproject:

  task writeClasspath << {
      buildDir.mkdirs()
      new File(buildDir, "classpath.txt").text = configurations.runtime.asPath +
                                                ":" + buildDir + "/libs/" +
                                                project.name + "-" +
                                                project.version + ".jar" + "\n"
  }

… and add the writeClasspath task to the CMakeLists.txt:

  catkin_rosjava_setup(installApp publishMavenJavaPublicationToMavenRepository writeClasspath)

• Replace all references to 'ias_knowledge_base' with knowrob_common. Please also check for other package names that may have changed.
• Rename all *.owl.in and *.pl.in files into *.owl and *.pl. Replace the @LOCAL_PACKAGE_PATH@ (or similar) directives with URLs of the form package:<ros_pkg_name>/local/path/to/file.owl, e.g. package:knowrob_common/owl/knowrob.owl. This new syntax works for loading OWL files both from OWL and Prolog files.
• Remove the 'false, false, true' arguments from all owl_parse() statements. The new syntax is simply

  owl_parse('package://<ros_pkg_name>/local/path/to/file.owl').

• Update launch files to the new json_prolog interface:

  <launch>
     <param name="initial_package" type="string" value="<pkg_name>" />
     <param name="initial_goal" type="string" value="owl_parse('package://<pkg_name>/owl/file.owl')" />
     
     <node name="json_prolog" pkg="json_prolog" type="json_prolog_node" cwd="node" output="screen" />
  </launch>

The changes have been ticketed at the knowrob repository for Milestone 1. Please have a look here for a list of changes: https://github.com/knowrob/knowrob/issues?milestone=1