====== Migrating to the catkinized version of KnowRob ======

Starting from ROS hydro/indigo, KnowRob has switched to the catkin buildsystem and the [[http://wiki.ros.org/rosjava|'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. **This page is aimed at maintainers of KnowRob packages that would like to upgrade them from the rosbuild- to the catkin-based version.**

===== Catkinization =====

As a first step, you can use the [[http://wiki.ros.org/catkin/migrating_from_rosbuild#Migration_Help_-_.22Catkinize.22_Scripts|'catkinize' scripts]] that generates something close to 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 in KnowRob  [[https://github.com/knowrob/knowrob/issues/18|that may have changed]].
  * Update the CMakeLists.txt and update all changed package names also there. Remove all rosbuild and old rosjava statements, e.g. those for generating .owl from .owl.in files.

===== Converting Java packages =====

Rosjava uses the gradle buildsystem that is at the moment (12/2014) only loosely integrated with catkin. Therefore, some information such as dependencies needs to be specified multiple times. Make sure to read the official documentation in the [[http://wiki.ros.org/rosjava|ROS wiki]] as well as the [[http://rosjava.github.io/rosjava_core/latest/|rosjava_core Sphinx documentation]] carefully to understand the main concepts first. 

==== Package structure ====

There is a one-to-many relation between catkin packages and "rosjava sub-projects" as described [[http://wiki.ros.org/rosjava/Anatomy%20of%20a%20RosJava%20Package|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 [[http://wiki.ros.org/rosjava/Tutorials/hydro/Unofficial%20Messages|subfolder with the name of the message package]]. This structure can be created using the tools in [[http://wiki.ros.org/rosjava_build_tools/Tutorials/hydro/Creating%20Rosjava%20Packages|rosjava_build_tools]]. 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
      \- ...


==== JAR files and build dependencies ====
Rosjava is now based on Maven that maintains a central repository of jar files for dependencies. The following snippet explains how dependencies are specified in the build.gradle of the respective subproject:
<code java>
    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'
    }
</code>
You can use the service at http://gradleplease.appspot.com/ to generate the lines to be put into the build.gradle


==== Run dependencies when calling Java from Prolog ====

In the 'normal' case, the classpath for a rosjava node only contains the dependencies of that program itself. 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. The classpath therefore needs to contain the Java dependencies of json_prolog itself AND the dependencies of the packages to be launched.

This is not easy with the existing tools: From json_prolog, we launch //catkin packages//, but the dependencies we need are specified by the //rosjava subprojects// inside those catkin packages. Since catkin is not aware of these subprojects, it cannot be used to collect the classpath elements from all dependencies. The current workaround is the following: During compilation, gradle creates a file 'classpath.txt' with the classpath elements 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:
<code java>
    task writeClasspath << {
        buildDir.mkdirs()
        new File(buildDir, "classpath.txt").text = configurations.runtime.asPath +
                                                  ":" + buildDir + "/libs/" +
                                                  project.name + "-" +
                                                  project.version + ".jar" + "\n"
    }
</code>
... and add the writeClasspath task to the CMakeLists.txt:
    catkin_rosjava_setup(installApp publishMavenJavaPublicationToMavenRepository writeClasspath)



===== Adapting OWL and Prolog files to the new libraries =====

  * Replace all references to 'ias_knowledge_base' with knowrob_common. Please also check for other [[https://github.com/knowrob/knowrob/issues/18|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. The //initial_package// parameter specifies the package to be loaded when the node is launched (similar to the package you give as argument to 'rosprolog'). The //initial_goal// is called immediately after KnowRob has been started and can for instance be used to load data from an OWL file.
    <code xml>
    <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>
    </code>
  * Replace all *.cs.tum.edu-IRIs with knowrob.org. You can use the following command to replace them in most common files in all subfolders of the current directory:
     <code bash>
     $ rosrun rosprolog migrate_owl_iri
     </code>


===== Changelog =====

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?q=is%3Aissue+milestone%3A1.0+