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Unofficial Messages

Description: Generating java artifacts for your own, unreleased message packages.

Keywords: rosjava

Tutorial Level: BEGINNER

Next Tutorial: To Build with Catkin or Gradle

Unofficial Messages

You can also generate code for your own non-released packages by creating a subproject in one of your gradle repositories.

This will also work for manually testing and building artifacts of released packages - just make sure the version number of your modified msg package is greater than the last officially released version.

Example

A good example of a mixed set of non-released and version bumped testing release packages can be found in rocon_rosjava_msgs.

Artifact Generator

This method generates a single artifact for a single unreleased message package. It can get tedious if you want to generate code for alot of message packages, but it is by far the easiest method.

• Create a regular foo_msgs package with your custom msgs and srvs.

• Create a gradle-catkin package 'myjava_messages'

• Create a gradle subproject in here called foo_msgs

• Add foo_msgs as a build_depends to myjava_messages/package.xml

• Add foo_msgs to myjava_messages/settings.gradle

• Add build rules and logic to your myjava_messages/build.gradle and myjava_messages/foo_msgs/build.gradle.

Catkin Create

You can simplify the process some with the wizards from rosjava_build_tools, There are two constraints that is important in order to make this process as automatic and simple as possible:

Example:

> cd src
> catkin_create_pkg foo_msgs std_msgs
> cd foo_msgs
# Add your messages to foo_msgs
# Don't forget to add message_generation/runtime depends
# in CMakeLists.txt and package.xml
> cd ../
# Good idea to include message package build_depends to your package
# - rosjava_bootstrap : for the message_generation tools
# - rosjava_messages  : for any official message artifacts you depend on
# - foo_msgs          : the unofficial package dependency you will need
> catkin_create_rosjava_pkg myjava_messages rosjava_bootstrap rosjava_messages foo_msgs
> cd myjava_messages
> catkin_create_rosjava_msg_project foo_msgs
> cd ../..
> catkin_make

Manually

You can of course set up foo_msg's build.gradle file manually and remove the constraints above. You'll just need to pay attention to get the dependencies and versions correct.

Under the Hood

Example generated code for the above is in foo.tar.gz. The meaningful snippets that are added to your package/project are outlined below. Should be self-explanatory.

myjava_messages/package.xml

?xml version="1.0"?>
<package>
  <name>myjava_messages</name>
  ...
  <!-- The message generator tools -->
  <build_depend>rosjava_bootstrap</build_depend>
  <!-- If foo_msgs depends on other official message artifacts -->
  <build_depend>rosjava_messages</build_depend>
  <build_depend>foo_msgs</build_depend>
  <!-- If foo_msgs depends on other unofficial messages, add them here -->
</package>

myjava_messages/settings.gradle

include 'foo_msgs'

myjava_messages/build.gradle

...

apply plugin: 'catkin'
project.catkin.tree.generate()

...

myjava_messages/foo_msgs/build.gradle

try {
    project.catkin.tree.generateMessageArtifact(project, 'foo_msgs')
} catch (NullPointerException e) {
    println("Couldn't find foo_msgs on the ROS_PACKAGE_PATH")
}

The generated artifact would appear in myjava_messages/devel/share/maven/com/github/rosjava/myjava_messages/foo_msgs when built.

Alternative Methods

You can also spawn multiple packages at once with some gradle-groovy logic - look to the scripts in rosjava_messages for hints on how to do that.

Another alternative is to bundle multiple message packages into the one rosjava artifact (or even all message packages on ROS_PACKAGE_PATH), but that requires looking into the functionality provided by the ros gradle plugins and the message_generation library in rosjava_bootstrap.

Both of these methods go beyond this tutorial - if you would like more information, ask on the sig mailing list.