Items tagged javascript, comet
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Why does Facebook chat use subdomains so aggressively?
Probably because it involves long-running connections. Browsers have a limit on the number of connections you can have open to the same domain at the same time (I think it’s 8 in most browsers these days). If Facebook chat opened a connection to www.facebook.com and you opened up 8 Facebook windows you would no longer be able to navigate to any more Facebook pages, since all 8 connections would be taken up by the long lived chat connections. By connecting to a different subdomain for each connection this problem can be avoided.
[... 107 words]Hookbox (via) For most web projects, I believe implementing any real-time comet features on a separate stack from the rest of the application makes sense—keep using Rails, Django or PHP for the bulk of the application logic, and offload any WebSocket or Comet requests to a separate stack built on top of something like Node.js, Twisted, EventMachine or Jetty. Hookbox is the best example of that philosophy I’ve yet seen—it’s a Comet server that makes WebHook requests back to your regular application stack to check if a user has permission to publish or subscribe to a given channel. “The key insight is that all application development with hookbox happens either in JavaScript or in the native language of the web application itself”. # 29th July 2010, 9:48 am
Realtime Election Tweets. Jay Caines-Gooby’s realtime election tweet service, using Node.js, nginx and WebSocket with a Flash fallback. # 6th May 2010, 9:20 pm
Lou’s Pseudo 3d Page. Spectacularly detailed exploration of the road graphics used in racing games prior to true 3D. This is a potential gold mine for anyone looking for a fun project to try out with canvas. Bonus points for comet integration—I’m still looking forward to the first real-time multiplayer game in the browser using comet and canvas. # 8th February 2010, 11:21 am
Comet (long polling) for all browsers using ScriptCommunicator. More Comet from the Plurk team: 80 lines of dependency free JavaScript implementing long polling using script tags (hence working cross-domain) across IE6+, Firefox, WebKit and Opera. The clever bit is the code to detect loading errors. It doesn’t try to fix the infinite loading indicator problem—is that still a cromulent usability concern? # 3rd February 2010, 12:37 am
Plurk: Instant conversations using Comet (via) Plurk’s comet implementation sounds pretty amazing. They’re using a single quad-core server with 32GB of RAM running 8 Node.js instances to serve long-polled comet to 100,000+ simultaneous users. They switched to Node from Java JBoss/Netty and found the new solution used 10 times less memory. # 1st February 2010, 10:13 am
Real time online activity monitor example with node.js and WebSocket. A neat exploration of Node.js—first hooking a “tail -f” process up to an HTTP push stream, then combining that with HTML 5 WebSockets to achieve reliable streaming. # 8th December 2009, 11:07 pm
Node.js is genuinely exciting
I gave a talk on Friday at Full Frontal, a new one day JavaScript conference in my home town of Brighton. I ended up throwing away my intended topic (JSONP, APIs and cross-domain security) three days before the event in favour of a technology which first crossed my radar less than two weeks ago.
[... 2009 words]EtherPad. Outstanding implementation of an online real-time collaborative text editor—basically SubEthaEdit in your browser. I can see myself using this a lot. # 24th July 2009, 12:35 am
Reverse HTTP Demo (via) This is a bit of a brain teaser—a web server running in JavaScript in your browser which uses long polling comet to respond to incoming HTTP requests channelled through a “Reverse HTTP” proxy. # 21st July 2009, 3:54 pm
Visualising Radio, pushing, not pulling. The BBC’s new radio player uses Comet over a Flash XMLsocket connection transport, with an ActiveMQ message queue behind the scenes. I’d like to know what server they’re using to broadcast out to the XMLsocket connections. # 13th January 2009, 12:59 am
FriendFeed launch a real-time API. This is huge: JSONP plus long polling Comet, with “everything since X” tokens to ensure you don’t miss anything. This is the first open Comet API I’ve seen anywhere. Combine this with FriendFeed’s regular API (which allows arbitrary message posting) and you’ve got a really powerful tool for hackers who want to experiment with Comet without rigging up their own infrastructure. # 22nd October 2008, 2:18 pm
Private Messages with cometD Chat. cometd-java (a Java servlet reference implementation of the Bayeux protocol) can be extended with BayeuxService subclasses that run within the server itself. # 16th October 2008, 2:14 pm
How Comet Brings Instant Messaging to meebo. “What started off as a hack appears to be fulfilling one of the most basic needs of the Web, which is live synchronous interaction”—Jian Shen # 27th July 2008, 11:18 am
Engineering @ Facebook: Facebook Chat. The new Facebook Chat uses Comet (long polling with a hidden iframe) against a custom web / chat server written in Erlang, designed to handle a launch to all 70 million users at once. It was tested using a “dark launch” period where live pages simulated chat request traffic without showing any visible UI. # 15th May 2008, 7:55 am
Persevere adds Comet Support. Persevere sounds neat: a RESTful HTTP/JSON data store (the interface reminds me of CouchDB) which recently gained the ability to “subscribe” to a resource and receive notifications of updates via comet. # 13th May 2008, 8:09 am
Comet at the Highland Fling. I thoroughly enjoyed the Highland Fling yesterday. Here are the slides from my talk on Comet. # 4th April 2008, 10:13 am
Internet Explorer 8 Readiness Toolkit. The new built-in development tools look similar enough to Firebug to make me very happy. Also of interest: Selectors API (for fast getElementsBySelector), CSS 2.1 support, support for XHTML style namespaces in HTML, an interesting Web Slices feature based on the hAtom microformat and 6 connections per host (up from 2) which should make Comet easier. # 5th March 2008, 6:28 pm
Gears 0.2 Released! New modules are HttpRequest and Timer, both for use within workers (which provide Erlang-style message passing concurrency). Particularly interesting is that the Gears HttpRequest module can be used for much cleaner Comet implementations in IE. # 5th March 2008, 12:21 am
Let me be again clear here that Comet isn’t a new single technique. Rather, it’s a combination of existing push technologies with further research into new methods that together provides a robust framework for pushing data to all clients on modern networks.
— Michael Carter # 3rd February 2008, 10:04 pm
$.comet (via) The first Comet (with Bayeux) plugin I’ve seen for jQuery—currently only handles long-polling over XMLHttpRequest, but still a promising start. # 9th January 2008, 8:31 am
Why we switched to Jetty. Zimbra (recently acquired by Yahoo!) are using Jetty for Comet. It sounds like they are using Bayeux as well. # 8th January 2008, 5:12 am
20,000 Reasons Why Comet Scales. Greg Wilkins coaxes Jetty and Bayeux in to supporting 20,000 simultaneous users per server while maintaining sub-second latency, using Amazon EC2 to run the benchmark. # 7th January 2008, 8:32 am
Django and Comet. How to build a chat application using Django and the Orbited comet server. Orbited can be set up to proxy most requests through to a Django backend while handling any comet requests itself. # 26th December 2007, 9:05 pm
The Future of Comet: Part 1, Comet Today. Absolutely the best summary I’ve seen of all of the current Comet techniques in one place. # 11th December 2007, 1:13 pm
JavaScript Internationalisation, explained by reindeer. “Santa even spooked Comet recently by talking about him as if he were some pushy web server.” # 8th December 2007, 2:04 pm
Comet works, and it’s easier than you think
I gave a talk this morning at the Yahoo! Web Developer Summit on Comet, cometd and Bayeux.
[... 1314 words]Jetty WebServer. Jetty 6.1 was the only cometd / Bayeux implementation I tried which worked out of the box. # 27th November 2007, 6:43 pm
A Taxonomy of Event- and REST-based Comet. Kris Zyp describes a conceptual model for Comet messages based on REST semantics (so you can send a PUT referencing a specific URI down to a client to represent an idempotent state change). # 21st November 2007, 8:18 pm
IE ActiveX(“htmlfile”) Transport, Part II. Fascinating tricks for working around IE memory leaks using explicit CollectGarbage() calls and setInterval() to an empty function. # 19th November 2007, 11:48 am