6. Developing OSGi Bundles

The Tools provide functionality that makes developing OSGi bundles, especially the editing of MANIFEST.MF files, easier.

6.1 Resolving Bundle Dependencies

While working with OSGi bundles, one of the most interesting and challenging aspects is defining the package, bundle, and library imports in the manifest and then keeping this in sync with your compile classpath either in Ant and Maven or Eclipse. In most cases you would typically be required to manually set up the Eclipse classpath. Ultimately, the Eclipse compile classpath is still different from the bundle runtime classpath, as normally an entire JAR file is being made available on the Eclipse classpath but not necessarily at runtime due to the explicit visibility rules defined in Import-Package headers.

The Tools address this problem by providing an Eclipse classpath container that uses an Virgo Runtime Environment-specific dependency resolution mechanism. This classpath container makes resolved dependencies available on the project’s classpath but allows only access to those package that are imported explicitly (e.g., via Import-Package ) or implicitly by using Import-Library or Import-Bundle .

To use the automatic dependency resolution, an OSGi bundle or PAR project needs to be targeted to a configured Virgo Runtime Environment instance. This can be done from the project’s preferences by selecting the runtime on the "Targeted Runtimes" preference page.

[Note]Note
In most scenarios it is sufficient to target the PAR project to a runtime. The nested bundles will then automatically inherit this setting.

After targeting the project or PAR you will see a "Bundle Dependencies" classpath container in your Java project. It is now safe to remove any manually configured classpath entries.

The classpath container will automatically attach Java source code to the classpath entries by looking for source JARs next to the binary JARs in the Virgo Runtime Environment’s repository. You can also manually override the source code attachment by using the properties dialog on a single JAR entry. This manual attachment will always override the convention-based attachment.