Service call backs to activity in android

I have a background service running and a client which interacts with the service.

When the client requests for some operation, the service performs it and it should send the result back to the activity (client).

I know how to invoke the service methods in activity and using call backs we can achieve what I want to do. But I am not able to开发者_运维技巧 understand the call back mechanism and code example provided in Api demos (remoteservice).

Could someone explain how this service callback works; or anything which is achievable using simpler mechanism.

Here is the flow
Create your intent to call a service. You can either startService() or BindService() with BIND_AUTO_CREATE

Once the service is bond, it will create a tunnel to talk with it clients which is the IBinder Interface. This is used by your AIDL Interface implementation and return the IBinder in

private final MyServiceInterface.Stub mBinder = new MyServiceInterface.Stub() {
    public int getNumber() {
        return new Random().nextInt(100);
    }
};

public IBinder onBind(Intent intent) {
    // TODO Auto-generated method stub
    Toast.makeText(this, "Service OnBind()", Toast.LENGTH_LONG).show();
    return mBinder;
}

Once it returns the mBinder, ServiceConnection that you created in the client will be called back and you will get the service interface by using this

           mConnection = new ServiceConnection() {

        public void onServiceDisconnected(ComponentName name) {
            // TODO Auto-generated method stub

        }

        public void onServiceConnected(ComponentName name, IBinder service) {
            // TODO Auto-generated method stub

            mService = MyServiceInterface.Stub.asInterface(service);


    };

Now you got the mService interface to call and retreive any service from that