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--- |
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labels: 'Stage-Beta' |
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summary: Subscribe to pubsub nodes using the HTML5 EventSource API |
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... |
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Introduction |
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------------ |
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[Server-Sent Events](https://en.wikipedia.org/wiki/Server-sent_events) |
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is a simple HTTP/line-based protocol supported in HTML5, making it easy |
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to receive a stream of "events" in realtime using the Javascript |
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[EventSource |
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API](https://developer.mozilla.org/en-US/docs/Web/API/EventSource). |
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EventSource is supported in [most modern |
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browsers](http://caniuse.com/#feat=eventsource), and for the remainder |
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there are 'polyfill' compatibility layers such as |
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[EventSource.js](https://github.com/remy/polyfills/blob/master/EventSource.js) |
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and [jquery.eventsource](https://github.com/rwldrn/jquery.eventsource). |
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Details |
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------- |
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Subscribing to a node from Javascript is easy: |
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var source = new EventSource('http://pubsub.example.org:5280/eventsource/mynode'); |
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source.onmessage = function (event) { |
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console.log(event.data); // Do whatever you want with the data here |
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}; |
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### Cross-domain issues |
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The same cross-domain restrictions apply to EventSource that apply to |
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BOSH, and support for CORS is not clearly standardized yet. You may want |
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to proxy connections through your web server for this reason. See [BOSH: |
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Cross-domain |
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issues](https://prosody.im/doc/setting_up_bosh#proxying_requests) for |
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more information. |
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Configuration |
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------------- |
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There is no special configuration for this module. Simply load it onto a |
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pubsub component like so: |
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Component "pubsub.example.org" "pubsub" |
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modules_enabled = { "pubsub_eventsource" } |
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As it uses HTTP to serve the event streams, you can use Prosody's |
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standard [HTTP configuration options](https://prosody.im/doc/http) to |
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control how/where the streams are served. |
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**Note about URLs:** It is important to get the event streams from the |
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correct hostname (that of the pubsub host). An example stream URL is |
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`http://pubsub.example.org:5280/eventsource/mynode`. If you need to |
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access the streams using another hostname (e.g. `example.org`) you can |
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use the `http_host` option under the Component, e.g. |
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`http_host = "example.org"`. For more information see the ['Virtual |
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Hosts'](https://prosody.im/doc/http#virtual_hosts) section of our HTTP |
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documentation. |
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Compatibility |
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------------- |
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------- -------------- |
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0.9 Works |
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0.8 Doesn't work |
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Trunk Works |
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------- -------------- |