server-sent events

# server-sent events

### another weird HTTP thang

Patrick Mueller
-
[`@pmuellr`](https://twitter.com/pmuellr)
-
[`muellerware.org`](http://muellerware.org)

developer advocate for IBM's [Bluemix](http://bluemix.net) PaaS

.smaller[.smaller[
<http://pmuellr.github.io/slides/2014/09-server-sent-events>
<br>
<http://pmuellr.github.io/slides/> (all slides)
]]

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layout: true

<div class="page-icon">
<span class="smaller"><span class="smaller"><tt>server-sent events</tt></span></span>

</div>

---

### wat

* aka `EventSource` aka `text/event-stream` resources

* like a one-way WebSocket, HTTP server to client

* **much** simpler protocol than WebSocket

* [W3C Server-Sent Events specification](http://www.w3.org/TR/eventsource/)

* more info: ["Stream Updates with Server-Sent Events" at WebPlatform.org](http://docs.webplatform.org/wiki/tutorials/eventsource_basics)

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### server

```js
//!snippet: server.js
```

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### client

```js
//!snippet: client.js
```

<span class="smaller"><span class="smaller"><tt>the server sent: 'the time is Mon Sep 22 2014 23:36:46 GMT-0400 (EDT)'</tt></span></span>

* "typed" events (type is a string)
  `source.addEventHandler("time-message", ...)`

* auto-reconnect, and "open and ""error" events

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### however ... ###

* no "close" or "readystatechange" events

* everywhere **BUT** IE and android < 4.4
  * see [caniuse.com's Server-sent DOM events page](http://caniuse.com/#feat=eventsource)

* polyfills available:

* [Yaffle/EventSource](https://github.com/Yaffle/EventSource/)
  * [remy/polyfills](https://github.com/remy/polyfills/blob/master/EventSource.js)
  * [rwaldron/jquery.eventsource](https://github.com/rwaldron/jquery.eventsource)

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# `fin`