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1803
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1 ---
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2 labels: 'Stage-Beta'
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3 summary: Subscribe to pubsub nodes using the HTML5 EventSource API
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4 ...
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5
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6 Introduction
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7 ------------
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8
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9 [Server-Sent Events](https://en.wikipedia.org/wiki/Server-sent_events)
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10 is a simple HTTP/line-based protocol supported in HTML5, making it easy
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11 to receive a stream of "events" in realtime using the Javascript
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12 [EventSource
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13 API](https://developer.mozilla.org/en-US/docs/Web/API/EventSource).
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14
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15 EventSource is supported in [most modern
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16 browsers](http://caniuse.com/#feat=eventsource), and for the remainder
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17 there are 'polyfill' compatibility layers such as
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18 [EventSource.js](https://github.com/remy/polyfills/blob/master/EventSource.js)
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19 and [jquery.eventsource](https://github.com/rwldrn/jquery.eventsource).
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20
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21 Details
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22 -------
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23
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24 Subscribing to a node from Javascript is easy:
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25
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26 var source = new EventSource('http://pubsub.example.org:5280/eventsource/mynode');
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27 source.onmessage = function (event) {
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28 console.log(event.data); // Do whatever you want with the data here
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29 };
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30
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31 ### Cross-domain issues
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32
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33 The same cross-domain restrictions apply to EventSource that apply to
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34 BOSH, and support for CORS is not clearly standardized yet. You may want
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35 to proxy connections through your web server for this reason. See [BOSH:
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36 Cross-domain
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37 issues](https://prosody.im/doc/setting_up_bosh#proxying_requests) for
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38 more information.
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39
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40 Configuration
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41 -------------
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42
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43 There is no special configuration for this module. Simply load it onto a
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44 pubsub component like so:
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45
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46 Component "pubsub.example.org" "pubsub"
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47 modules_enabled = { "pubsub_eventsource" }
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48
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49 As it uses HTTP to serve the event streams, you can use Prosody's
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50 standard [HTTP configuration options](https://prosody.im/doc/http) to
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51 control how/where the streams are served.
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52
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53 **Note about URLs:** It is important to get the event streams from the
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54 correct hostname (that of the pubsub host). An example stream URL is
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55 `http://pubsub.example.org:5280/eventsource/mynode`. If you need to
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56 access the streams using another hostname (e.g. `example.org`) you can
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57 use the `http_host` option under the Component, e.g.
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58 `http_host = "example.org"`. For more information see the ['Virtual
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59 Hosts'](https://prosody.im/doc/http#virtual_hosts) section of our HTTP
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60 documentation.
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61
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62 Compatibility
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63 -------------
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64
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65 ------- --------------
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66 0.9 Works
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67 0.8 Doesn't work
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68 Trunk Works
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69 ------- --------------
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