Refactor out EventMachine dependencies.

[digitalextremist]

Even though Celluloid and EventMachine are mutually exclusive, when Reel is installed, EventMachine comes along, because whether used or not, websocket-driver and other faye-* gems bring in an EventMachine dependency. This has affected actioncable also, through faye-* dependencies, and it is being addressed in this thread: rails/actioncable#16

In our next release bringing in HTTP/2 ( #198 ) we need to also refactor out dependencies which bring in EventMachine, whether it be used or not, and provide complete Celluloid::IO support for websockets, by refactoring the faye-* gems in parallel with this next release.

This will be achieved one of two ways:

1. Working with @jcoglan to remove EventMachine in a version of his gems.
2. Fork and refactor the faye-* gems as Celluloid::WebSocket which would also solve our need to bring celluloid-websocket-client back up to speed with the faye-* gems.

/cc: @tarcieri, @dhh, @jcoglan, @kenichi, @jasonayre

[jcoglan]

faye-websocket depends on EM but websocket-driver does not. The intention was always for websocket-driver to allow easy WebSocket integration into other I/O stacks.

[Asmod4n]

websocket-driver is also quite easy to integrate into a celluloid-io loop: https://gist.github.com/Asmod4n/241c84ef31df921b31e9/c15bd4e3be2efd261f325d18eec126f1e9649b62

[digitalextremist]

Thanks @jcoglan, that makes sense and explains what I've been seeing. EM is only listed as a development dependency for websocket-driver I now see. And agreed, @Asmod4n. I've seen and worked on several implementations like that. Thinking out loud...

Maybe we ought to extract all websocket code from Reel, and create reel-websocket both for client and server uses, fleshing out WebSocket::Driver in pure Celluloid::IO rather than focusing on the Rack approach being primary... of hijacking.

We can support hijacking in the reel-rack handler, but reel-websocketought to be a pure ruby, pure I/O base for that. Thenreel-websocketcan be used byReelitself andAngelo... half as a standardized "Celluloid WebSocket" and half as aWebSocket::Driver` abstraction layer.

[jcoglan]

@digitalextremist Yep, EM is only used to run the example in the websocket-driver repo, it's not a runtime dep.