Google added support for partial response and an improved version of partial update, called "patch," to a number of newer APIs such as Buzz, URL Shortener, Tasks and many all others APIs available in the Google APIs Discovery Service and the APIs Explorer are now supporting this feature, blogged Anton Lopyrev, Associate Product Manager for Google APIs.
"The partial response algorithm is identical to what was provided by the Google Data Protocol. By supplying a fields query parameter to any API call that returns data, you can request specific fields. Here's an example request that returns only titles and timestamps of a user's public Buzz activities:
https://email@example.com/@public?alt=json&pp=1&fields=items(title,updated). Given that the full response is around 53KB and the partial response is only 3KB, the data sent to the client is reduced by almost 95%!," explains Lopyrev.
"While the partial response algorithm is unchanged, the partial update algorithm has changed significantly compared to what was provided by Google Data Protocol. We've received feedback that the old algorithm was too complicated and hard to use, which prompted us to design something much simpler. The basics remain the same: you can use the HTTP PATCH verb in supported API methods to send partial updates to Google servers. However, the mechanics are different. Adding and modifying data uses the same 'merge' semantics as before. But deleting is simplified; just set a field to 'null'. Of course, the devil is in the details, so please check out the documentation for the nitty gritty," Lopyrev said.
"You can try out both partial response and patch algorithms in the APIs Explorer. For partial responses, the fields parameter is available for most methods. In addition, the partial update methods are denoted by .patch in the method name. You can try both the fields parameter and the patch method on the "tasklist" resource in the APIs explorer," Lopyrev added.
[Source:Google Code blog]