This is an example of creating a realtime chat server using WebSockets with the snap framework. This is accompanied by a blog post that you can read for some basic guidance. It is intended simply as an example and is NOT intended for production use. There are very obvious performance and security concerns with this code. First of all, user input is not santized (i.e. clients may send malicious Javascript directly through chat) and the threading model is far from ideal.
I was learning some of these frameworks as I wrote this code, so it may not be the absolute best way (but, is there ever really such a thing?) to operate within the model provided by the frameworks, but you can certainly use this as a starting point for determing how things are to be done.
To build and run this code, first create a table called "chat" in your PostgreSQL database. Then load the schema located in "bootstrap" into this table. From there, run the following commands:
cabal sandbox init
cabal install --dependencies-only
cabal runAll functionality is located at the /chat endpoint. This endpoint is protected by the auth system, so you must first create an account and login. After having done this, try visiting
Similarly, after you have chatted for a little bit of time, you can visit http://localhost:8000/chat/last to see a history of your last 50 messages (note: all messages are still in the DB, but this endpoint only displays 50).