This is not an optimal solution, but I'm working on an Android app that must consume GTFS-Realtime data as an API is not available. The datasets will be small, the max # of vehicles being tracked at one time will be 8-10, or I would consider building my own API.
Since the common practice is to consume GTFS-Realtime data from a server which exposes an API, I can't find any good examples of implementing the "gtfs-realtime.proto" to process Google's protocol format on the mobile device
My Question: Are there any open projects that demonstrate consuming GTFS-Realtime using the protocol buffer format implementation using Android Natively? I checked github and most everything leads to OneBusAway, which requires their API which I'm not interested in using.
The closest implementation I've seen is this sample done in Ruby: https://github.com/reidab/trimet-gtfs-realtime
Or a Java version of Ruby's "Beefcake" would be a start.