expose html5 server sent events (sse) as a writable stream
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Expose HTML5 Server Sent Events as an installable appliance on Node.JS http servers; connections are emitted as Writable streams.

var http = require('http')
  , fs = require('fs')
  , through = require('through')
  , sse = require('sse-stream')('/sse')
  , serv

module.exports = serv = http.createServer(function(req, resp) {
  resp.setHeader('content-type', 'text/html')
  resp.end('<html><body><script type="text/javascript">('+js+')()</script></body></html>')


sse.on('connection', function(client) {
    .pipe(through(function(buf) { this.emit('data', buf.toString()) }))

// client-side code:
function js() {
  var es = new EventSource('/sse')
    , pre = document.createElement('pre')
    , closed = false


  es.onmessage = function(ev) {
    if(closed) return


    window.scrollTo(0, pre.clientHeight)

  es.addEventListener('end', function() {
    closed = true
  }, true)

  es.onerror = function(e) {
    closed = true


sse = require('sse-stream')(path | options)

Create a SSE server that emits connection events on new, successful eventstream connections.

The argument may either be a string path to listen on (defaults to /sse/) or an object:

{ path: '/listen/on/this/path'
, keepalive: 1000 }

keepalive determines the interval time in ms that keepalives will be sent to all connected clients.

sse.on('connection', function(client))

client is a writable stream representing a client connection (request response pair).

Of note, all data sent through this connection will be stringified before sending due to the event stream spec.

client.retry(integer ms)

Send a "retry" message that lets the client know how many MS to wait until retrying a connection that ended.