The Android SDK comes with a SampleSyncAdapter project for implementing a synced connection to a cloud-type service. The class NetworkUtilities takes care of making the actual HTTP requests, and generally has to be tailored to work with a particular cloud service (apart from the sample server app included with the SDK).
Here is a base class that handles the session-based authentication for Drupal’s JSON Server module. Extend this class to implement the calls for a particular service model via Drupal / JSON Server.
I've been having a hard time trying to train a Self-Organizing Map to categorize a large pool of short documents by my selected keywords. The initial results were promising but I couldn't adjust the training parameters well enough to train the error sufficiently low that I would be confident of the categorizations, even after several days of training.