How do you build a real-time API as opposed to the standard web based APIs?

Question

..also, are there limitations between implementation technologies and the devices/languages that can access those API methods - as opposed to the standard HTTP API methods where all devices/languages can access HTTP?

Answer 1

There is plenty ways to do what you want to do. It is like the twitter stream thing. You can write your own protocol/network daemon or use a "ready for use" framework which permit to build your own network app, like nodejs or ape. I let you refer to their tutorials.