view mod_pubsub_eventsource/README.markdown @ 4629:0e60ce83205c

mod_s2s_keepalive: Ignore errors from the local server If a stanza can't be delivered and instead an bounce is generated, the origin of the error, when different from the stanza 'from' should be indicated in the 'by' attribute of the <error>, which we look for here so this doesn't count as a successful ping. An error that does come from the remote means we have connectivity, but probably no XEP-0199 handling. This is fine. We care about connectivity, not protocol.
author Kim Alvefur <zash@zash.se>
date Wed, 21 Jul 2021 15:57:13 +0200
parents 4d73a1a6ba68
children 694b62d8a82f
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---
labels: 'Stage-Beta'
summary: Subscribe to pubsub nodes using the HTML5 EventSource API
...

Introduction
------------

[Server-Sent Events](https://en.wikipedia.org/wiki/Server-sent_events)
is a simple HTTP/line-based protocol supported in HTML5, making it easy
to receive a stream of "events" in realtime using the Javascript
[EventSource
API](https://developer.mozilla.org/en-US/docs/Web/API/EventSource).

EventSource is supported in [most modern
browsers](http://caniuse.com/#feat=eventsource), and for the remainder
there are 'polyfill' compatibility layers such as
[EventSource.js](https://github.com/remy/polyfills/blob/master/EventSource.js)
and [jquery.eventsource](https://github.com/rwldrn/jquery.eventsource).

Details
-------

Subscribing to a node from Javascript is easy:

    var source = new EventSource('http://pubsub.example.org:5280/eventsource/mynode');
    source.onmessage = function (event) {
      console.log(event.data); // Do whatever you want with the data here
    };

### Cross-domain issues

The same cross-domain restrictions apply to EventSource that apply to
BOSH, and support for CORS is not clearly standardized yet. You may want
to proxy connections through your web server for this reason. See [BOSH:
Cross-domain
issues](https://prosody.im/doc/setting_up_bosh#proxying_requests) for
more information.

Configuration
-------------

There is no special configuration for this module. Simply load it onto a
pubsub component like so:

    Component "pubsub.example.org" "pubsub"
      modules_enabled = { "pubsub_eventsource" }

As it uses HTTP to serve the event streams, you can use Prosody's
standard [HTTP configuration options](https://prosody.im/doc/http) to
control how/where the streams are served.

**Note about URLs:** It is important to get the event streams from the
correct hostname (that of the pubsub host). An example stream URL is
`http://pubsub.example.org:5280/eventsource/mynode`. If you need to
access the streams using another hostname (e.g. `example.org`) you can
use the `http_host` option under the Component, e.g.
`http_host = "example.org"`. For more information see the ['Virtual
Hosts'](https://prosody.im/doc/http#virtual_hosts) section of our HTTP
documentation.

Compatibility
-------------

  ------- --------------
  0.9     Works
  0.8     Doesn't work
  Trunk   Works
  ------- --------------