This is an example following the google developer training post which covers how to implement a SyncAdapter as well as the other components needed to plug a sync adapter into the framework.

While it is possible to implement network sync code, using this framework allows developers to take advantage of several features:

• Plug-in architecture
• Automated execution
• Automated network checking
• Improved battery performance
• Account management and authentication

It should be noted that sync adapters run asynchronously. Data is transferred regularly and efficiently, but not instantaneously. If one needs to do real-time data transfer, another approach such as AsyncTask or IntentService should be used.

SyncAdapters can be triggered into performing sync through a few approaches.

• When server data changes
• When content provider data changes
• Periodically
• On demand

Server data changes recognized/captured using GCM then running a call to ContentResolver.requestSync(), While content provider changes can be caught with content observers that trigger sync with the same call.

Periodical sync can take place by making an addPeriodicSync() call to the contentResolver or using an Alarm then triggering the sync with requestSync() call.

On demand can be made any time by simply calling ContentResolver.requestSync() and passing the expected information as bundle extras. Documentation suggests not performing on demand sync.

This example makes sync requests on demand during the activities onResume() method.