osgi dependency injection between services

Question

I just started playing around with OSGi services and have the following situation. I have a project which contains 2 services. Service A requires Service B, so I tried to inject the dependent service using

@Inject
private ServiceB svc;

but the framework wont inject. If I setup the following two methods in Service A and set these methods as "bind / undbind" in my OSGi componentA.xml the framework calls these methods and I can use Service B in Service A.

public synchronized void bind(IServiceB service)
{
  this.svc = service;
}

public synchronized void unbind(IServiceB service)
{
  if (this.svc == service)
  {
    this.svc = null;
  }
}

The question is, why does it not work with @Inject ? Sorry if this is a stupid question, I'm quite new to this whole topic. Many thanks in advance!

Answer 1

It looks like you are using Declarative Services, which does not support field injection or the JSR-330 annotations. Field injection has limited utility in OSGi, where services may be injected or "un-injected" at any time. Method injection is more generally useful because it gives you an opportunity to do something when this happens.

However I do urge you to use the annotations for Declarative Services. This will save you from having to write the component.xml by hand.