OSGi中的传递依赖

Question

I'm getting a NoClassDefFoundError at runtime and I thought the "uses" directive would avoid this because I thought it created transitivity (correct me if I'm wrong). Here is my configuration:

Bundle 1 
  Export-package A

Bundle 2 
  Export-package B, uses "A"
  Import-package A

Bundle 3
  Import-package B

Now, the exception happens when Bundle 3 makes a call to a class in B which in turn makes a call to a class in A . Based on the console, i can see that the BundleClassLoader looks for the class in bundle 3 (in other words, in itself), but not in Bundle 1 where it would find it. If i force BND to import A in Bundle 3 everything works fine, but it looks too labor intensive. i feel like I'm missing something. Shouldn't equinox use the info in the manifests to set the bundle classpath? or in the worst case, shouldn't BND detect the dependency of 3 on 1 and import package A in the manifest of 3?

All my bundles are active and i have no uses constraint violations

Answer 1

Bundle 2 must also import A. The uses A says that any bundle that imports my B and also imports A must import the same A as me. Since bundle 2 does not import A, this doesn't work. Also, bundle 3 needs to import A since B uses A. Any importer of B is also a user of A and so must import A.