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    <p>Basically what you need is to implement <a href="http://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern" rel="noreferrer">Publish-subscribe</a> on top of Atmosphere.</p> <p>Atmosphere consists of two parts: client-side (javascript-based) and server-side(java-based).</p> <p>First of all you need to configure server-side: <a href="https://github.com/Atmosphere/atmosphere/wiki/Installing-Atmosphere" rel="noreferrer">Installing Atmosphere</a></p> <p>Namely servlet or filter, it is required so that it could add <a href="https://github.com/Atmosphere/atmosphere/wiki/Understanding-AtmosphereResource" rel="noreferrer">AtmosphereResource</a> to the <em>HttpServletRequest</em>. </p> <p><a href="https://github.com/Atmosphere/atmosphere/wiki/Understanding-AtmosphereResource" rel="noreferrer">AtmosphereResource</a> represents a single client connection on the server-side.</p> <p><em>Broadcaster</em> is actually a container for these resources, so that you don't need to handle lookup/iteration/concurrency when you need to send to multiple connections. (Note that multiple connections can be produced by single client).</p> <p>On the server-side you need to provide clients an endpoint to subscribe for notifications. For example, if you are using Spring-MVC, it could go like this (omitting validations/authentications, etc.):</p> <pre class="lang-java prettyprint-override"><code>@RequestMapping(value = "/user-notifications/{userId}") @ResponseStatus(HttpStatus.OK) @ResponseBody public void watch(@PathVariable("userId") String userId, HttpServletRequest request) throws Exception { //Atmosphere framework puts filter/servlet that adds ATMOSPHERE_RESOURCE to all requests AtmosphereResource resource = (AtmosphereResource)request.getAttribute(ApplicationConfig.ATMOSPHERE_RESOURCE); //suspending resource to keep connection resource.suspend(); //find broadcaster, second parameter says to create broadcaster if it doesn't exist Broadcaster broadcaster = BroadcasterFactory.getDefault().lookup(userId,true); //saving resource for notifications broadcaster.addAtmosphereResource(resource); } </code></pre> <p>When something happens you can notify clients like this:</p> <pre><code>public void notify(User user, Event event){ Broadcaster b = BroadcasterFactory.getDefault().lookup(user.getId()); if (b!=null){ b.broadcast(event); } } </code></pre> <p>On the client side you need to send a subscribe request and listen for subsequent events, like this:</p> <pre class="lang-javascript prettyprint-override"><code>var request = new atmosphere.AtmosphereRequest(); request.url = '/user-notifications/'+userId; request.transport = 'websocket'; request.fallbackTransport = 'streaming'; request.contentType = 'application/json'; request.reconnectInterval = 60000; request.maxReconnectOnClose = 1000; request.onMessage = function(response){ console.log(response); alert('something happend&lt;br&gt;'+response); }; that.watcherSocket = atmosphere.subscribe(request); </code></pre> <p>So, to sum it up:</p> <ol> <li>Client sends request "I want to receive this kind of notifications".</li> <li>Server receives request, suspends and saves connection somewhere (either in your code or in Broadcaster).</li> <li>When something happens server looks for suspended connection and sends notification in it.</li> <li>Client receives notification and callback is invoked.</li> <li>Profit!!!</li> </ol> <p><a href="https://github.com/Atmosphere/atmosphere/wiki" rel="noreferrer">This wiki</a> has explanations for some concepts behind Atmosphere and links to other documentation.</p>
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