As a simple example, a server stores posts and clients can create posts. Other clients should receive updates, when a new post is created, based on a post subscription.

Embedded Device --(creates_post)--> Data Server <--(subscribes)-- Some Client we don't know yet

The server is set up with a schema that includes a subcription.
Using graphiql on the server I can subscribe to post_created that is triggered whenever a new post is created and updates are displayed in graphiql whenever I create a new Post by using HTTPoison through the elixir shell.

Communication is done using phoenix channels between the server and graphiql, right?
Thats not really something I can use to communicate with some client that I do not know much about.
How would I expose the subscription to a graphQL client?
I probably cant use phoenix channels and read something about Apollo?
Is there a more generic way or would apollo be the generic way?