I am looking for a platform agnostic framework or library that can give me a generalise schema for different responses coming from Messenger, Slack, Web chat, Skype etc. And, i can reply them with a single schema.
So, Any bot framework that have its own request and response schema.
Have you checked Microsoft Bot Framework? It's exactly what you are looking at.
The Microsoft Bot Framework provides just what you need to build and connect intelligent bots that interact naturally wherever your users are talking, from text/sms to Skype, Slack, Kik, Office 365 mail and other popular services.
The Bot Framework has a number of components including the Bot Connector, Bot Builder SDK, and the Bot Directory.
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