Websocket streams

[mdobson]

Adding a websocket link that conforms to the multiplex websocket protocol detailed here:

https://docs.google.com/document/d/1-vkl6o5PjdgsPACXEo80-sF9gPkK9JNIGKxZ8G-2rtM

[mdobson]

Currently this branch will not allow you to subscribe to _peer/connect and _peer/disconnect events.

[mdobson]

Fixt ^^

[kevinswiber]

There are a few things to watch out for when building these URLs, such as... is there a forwarded protocol? Is this an HTTP client connection or a SPDY client connection? See here:

zetta/lib/api_formats/siren/server.siren.js

Lines 10 to 15 in 3a7eb1d

	var isForwardedProtocol = context.env.request.headers.hasOwnProperty('x-forwarded-proto') &&
	['http', 'https'].indexOf(context.env.request.headers['x-forwarded-proto']) !== -1;
	var isSpdy = !!context.env.request.isSpdy && !isForwardedProtocol;
	var rootPath = env.helpers.url.path(loader.path);
	var eventPath = isSpdy ? rootPath + '/events' : rootPath.replace(/^http/, 'ws') + '/events';

[mdobson]

+1. Added a test case for this, and functionality to properly calculate.

[mdobson]

Talked with @AdamMagaluk thinking that we actually remove this link for SPDY responses entirely. Currently this feature is only really going to work over websockets.

[kevinswiber]

This is really cool stuff. Is any of this functionality exposed to the Zetta runtime or is it all C2Z/Z2Z API? To enable this inside apps and scouts, we could probably do something like:

module.exports = function(server) {
  var stream = server.createReadStream('*/led/*/state', { limit: 100 });
  stream.on('data', function(msg) {
    // awesome!
  });
};

[AdamMagaluk]

@kevinswiber Currently no, this PR just focuses on the ws side of things. But yes that would be great in the app.