Question

I have written an OSGi bundle to use it in my eclipse 4 rcp application. The usage of the service works fine if I add the dependencies, register these service in my activator and inject it in my class.

In activator

IUserService service = new TestUserService();
context.registerService(IUserService.class.getName(), service, null);

In my class

@Inject
IUserService service;

service.getSth();

I read that using bundles via declarative services should be the better way. So changed my implementation.
I created a component definition in my bundle to provide my service:

<?xml version="1.0" encoding="UTF-8"?>
<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0" name="usermanagement.test">
   <implementation class="usermanagement.test.TestUserService"/>
   <service>
      <provide interface="usermanagement.IUserService"/>
   </service>
</scr:component>

Then I removed the service registration from my activator and created an service consumer class:

public class UserServiceConsumer {

    private IUserService service;

    public synchronized void setQuote(IUserService service) {
        this.service = service;
    }

    public synchronized void unsetQuote(IUserService service) {
        if (this.service == service) {
            this.service = null;
        }
    }

}

and another component definition:

<?xml version="1.0" encoding="UTF-8"?>
<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0" name="UserServiceConsumer">
   <implementation class="services.UserServiceConsumer"/>
   <reference bind="setService" cardinality="1..1" interface="usermanagement.IUserService" name="IUserService" policy="static" unbind="unsetService"/>
</scr:component>

After these modifications the injection of my serivce does not work anymore. The problem is that the injected service reference is NULL everytime.

Does anyone know why? Did I forgot something?

Thanks a lot!

Answer 1

I can suggest a few things you can do to debug.

1. Have you actually got an scr implementation in your runtime? SCR (another name for declarative services) isn’t included in Equinox core, so you’ll need to include it. Most people use the Felix SCR bundle – it will sit very happily on top of Equinox.

2. Since Declarative Services just use services, you can change one half of your app at a time, to identify whether it’s the service consumption or registration which isn’t working.

3. You can also use the Equinox console to inspect your service registration. Use ‘ss’ to identify your bundle, then ‘bundle [no]’ to see what services are registered and consumed. If you’re using Felix SCR, there are also Equinox console extensions, so you can use ‘scr list’ to see all services which a bundle attempts to register (and their state), and ‘scr info’ for more details on a particular service.