5GMS - Media Session Handler - Basic architecture and Interfaces

[dsilhavy]

Feature description
Define the code architecture and the required interfaces. Ideally, people can fork the repository afterwards and implement the interfaces related to a specific feature

Relevant specifications and corresponding sections
26.501 - 5G Media Streaming (5GMS); General description and architecture (Release 17)
26.512 - 5G Media Streaming (5GMS); Protocols (Release 17)

[rjb1000]

(Some thoughts inspired by the discussion on 5G-MAG/rt-5gms-media-stream-handler#2, @dsilhavy, @jordijoangimenez, @haudiobe, @davidjwbbc.)

During an informal SA4 discussion this afternoon, we identified the fact that different 5GMS-Aware Applications don't share media session handling state. In fact, for data privacy reasons, it may be desirable for each application to run its instance of the Media Session Handler with a private M5 HTTPS session with the 5GMS AF.

So, while it might make sense to develop the Media Session Handler as a bound background Android service in this repository, and for this service to expose its M6 API via a suitable Android Inter-Process Communication mechanism, it should also be possible to bundle the Media Session Handler in the same application package as the 5GMS-Aware Application itself and it should be possible for the Media Session Handler to run in the same process as the application code.

Of course, appropriate consideration needs to be given to the thread model in this process so that media processing activities (e.g. playback) can continue in parallel with ancillary activities (e.g. reporting).