How two dependent bundles in osgi gets compiled

Question

I am learning OSGi framework. What i found that Bundles consists of .class files and manifest file. Now suppose I have two bundles A and B and bundle B depends on bundle A's service. So while compiling bundle B i have to keep Bundle A's service class in the classpath of bundle B or have to keep it(Bundle A's service) inside bundle B so that compiler can compile. Now if we are doing so then how modularity is achieved and how the two bundles are independent. Please help. Thanks

Answer 1

Use interfaces!!

You have in interface I. Class A implements I and therefore depends on it, both at compile time and at runtime. Class B uses an instance of I, which it obtains as an OSGi Service. Therefore B depends on I at compile time and at runtime.

Therefore neither A nor B has direct knowledge of each other. Implementation code is hidden, only the interface is visible and shared. And that's how modularity is achieved.

Answer 2

Manually doing dependency management is error prone. I suggest you use maven to manage the dependencies. In addition, maven-bundle-pluginIn could help you check import/export bundle at compile time; while maven-eclipse-plugin help you generate eclipse projects according to the dependency configuration in pom.