Programming

If I were you, I would make a table of all the various messaging system and list their API's (if any); and then I would focus on systems with supported APIs.

For example, Signal has a defined API with developer libs, as I recall.

https://signal.org/docs/

GitHub - signalapp/libsignal-protocol-c: Signal Protocol C Library

Also, WhatsApp has an API,

Twilio API for WhatsApp | Send messages, alerts and notifications on WhatsApp using Twilio WhatsApp Messaging API.

You should do a full survey of the SOTA and what APIs are available first, if you are going to go down this path.

OK, understood. I actually use talk - rarely, but with one working in the data center and the other colleague in the office it is often easy and convenient to use it for communication. Wouldn't your project be somewhat like the Pidgin Chat Client just extended to support talk? You might want to consider joining this project and writing exactly this extension.

bakunin

Rather than being client my program would work as a relay bridge.



--- Post updated at 03:59 PM ---

Here seems to be some source codes for GNU Talk: GNU Talk Homepage. I was planning to use those as the basis of my program. I need to see how it is possible to redirect messages from talk.