For anyone stumbling on this post now I’d recommend trying out this library that is made to modularize a Phoenix Channel:

https://github.com/doorgan/channel_handler

Can you share your current channel code? it would be easier to say more if we have a real example to discuss. Thanks!

With full blown WebSocket APIs I also dislike them getting too big so I split them into sub-channels with a tiny bit of pattern matching, this way I can have the handlers separate (they still don’t do anything but delegate to context services), that keeps the files reasonably small.

Here is an example of a channel that delegates to subtopics:

alias App.Service.Channel.{Faq, Learning, Search} # etc

  # join clauses
  
  def handle_in("faq:" <> msg, payload, socket), do: Faq.process_message(msg, payload, socket)

  def handle_in("learning:" <> msg, payload, socket), do: Learning.process_message(msg, payload, socket)

  def handle_in("search:" <> msg, payload, socket), do: Search.process_message(msg, payload, socket)

 # etc

Frontend can then send a message such as search:find with some payload, the channel will process it and call process_message in Search service with find message.