API Protocol Consultation

1.5 hours consultation via video call [Removed by Freelancer.com Admin for offsiting - please see Section 13 of our Terms and Conditions]. Scheduled within 3 days of accepting this contract. When you bid, please let me know why you are qualified in this area. Ideally, you have worked on APIs, AWS, XMPP, etc. I will be overseeing the building of a system that will, in the future, include a Linux server application running on an AWS instance. But first, I need to determine what type of communication protocol the server should use in communicating with client applications. Server: Linux AWS Service: API Similar to: [login to view URL] [login to view URL] Clients: multiple at the same time. From Android, IOS, Windows 10, etc. In the future, I will provide code examples for my customers to utilize this API from common languages like Python, Java, etc. This protocol should be quite flexible: low latency, bi-directional traffic. User authentication. Encryption. File transfers. Streaming media. Rich text. Web links, etc. From a simple chat session to a rich stream from a robot. Scalable. What I have looked at (briefly): XMPP, JSON, RPC and gRPC What do you recommend and why? I will probably contract with several experts to get multiple opinions on this. Thank you for your time.