In Virgil Dobjanschi talk during Google I/O he mentioned using Services for doing the fetching and then using a callback to notify the Activity when this was completed. He never went into specifics on how to implement this callback and I can't seem to find anything helpful on this topic anywhere.
I think he said that you didn't need to implement binding at all?
Any clues?
Option #1: Service sends a broadcast Intent, which the Activity catches via a BroadcastReceiver registered via registerReceiver().
Option #2: If the Activity is binding to the Service, have the Activity pass a listener to the Service, which the Service invokes when the work is complete.
Option #3: Service doesn't do much, but the ContentProvider calls notifyChange() when the data changes, which can ripple back through to the Activity and/or its Cursor on the data.
Option #4: Singletons, which should be avoided.
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Option #237: Service sends a letter via FedEx to the Activity. :-)
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All that being said, once they release the Twitter app as open source, you'll know for certain what the Twitter app does.
i think they're talking ab out using AIDL to communicate between the activity & the service...
Check out the Google I/O 2010 app. It uses the pattern he was referring to. It uses Option #2 from CommonsWare's answer.