Best way to convert existing java projects to osgi bundles

Question

We have lot of components out of which we want to modularize only a few to start with. Wondering what is the best way (in the context of my build environment) to create bundles

Answer 1

Start by only changing the MANIFEST.MF entries such that all your artifacts become bundles - they obviously won't magically work but it's a good non-destructive first step.

When using the maven-bundle-plugin ensure you set extensions and supportedProjectTypes as you may have problems with CI builds, Maven repos and m2e failing if the packaging type is bundle (see end).

Test your riskiest/core external dependencies early on - for example if you're using JPA for persistence then ensure that the provider works in an OSGi environment with your domain bundle and JDBC driver.

If you're migrating from Java EE/spring look at Karaf or Virgo. But if your components are for embedded systems or have no external dependencies the Felix or Equinox may be enough (though check out the pax-url project if that's the case).

Might be worth editing your question to be a bit more specific about the domain/technologies?

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eclipse:eclipse only generates that when the project is first configured, m2e's lifecycle problems might be a bit of pain but it's far better than using the old eclipse plug.

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The following will add manifest entries to your existing artifacts without changing them in any other way. It tells the standard maven jar and war plugins to use the MANIFEST.MF generated by maven-bundle-plugin.

Put this in the parent POM:

    org.apache.felix
    maven-bundle-plugin
    2.3.7
    true
    
        
            true
        
        
            jar
            war
        
        
            ${project.organization.name}
            ${project.organization.name}
            ${project.organization.url}
            ${project.description}
            ${bundle.doc.url}
            ${bundle.category}
            ${project.artifactId}
            ${project.version}

            *
            *
        
    
    
        
            bundle
            
                manifest
            
            prepare-package
            true
        
    



    org.apache.maven.plugins
    maven-jar-plugin
    2.3.1
    
        
            ${project.build.outputDirectory}/META-INF/MANIFEST.MF
        
    



    maven-war-plugin
    2.1.1
    
        
            create-war
            package
            
                war
            
            true
        
    
    
        
            ${project.build.outputDirectory}/META-INF/MANIFEST.MF
        
    

Then in child POMs, you may simply do:

    
        
            org.apache.felix
            maven-bundle-plugin
        
        
        
            org.apache.maven.plugins
            maven-jar-plugin