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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<style type="text/css">
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ul {
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padding: 0;
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margin: 0;
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}
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</style>
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<script type="text/javascript" src="sh_main.js"></script>
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<script type="text/javascript" src="sh_javascript.min.js"></script>
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<link type="text/css" rel="stylesheet" href="pipe.css" />
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<link type="text/css" rel="stylesheet" href="sh_vim-dark.css" />
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<meta http-equiv="content-type" content="text/html; charset=utf-8" />
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<title>node.js</title>
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</head>
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<body onload="sh_highlightDocument();">
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<div id="toc">
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<ol>
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<li><a href="#audience">Audience</a></li>
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<li><a href="#about">About</a></li>
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<li><a href="#download">Download</a></li>
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<li><a href="#build">Build</a></li>
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<li><a href="#demo">Demo</a></li>
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<li><a href="#community">Community</a></li>
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<li><a href="api.html">Documentation</a></li>
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</ol>
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</div>
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<div id="content">
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<h1><a href="http://tinyclouds.org/node">Node</a></h1>
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<p id="introduction">
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Event-based I/O for
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<a href="http://code.google.com/p/v8/">V8 javascript</a>.
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</p>
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<p>
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An example of a web server written with Node which responds with
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"Hello World" after waiting two seconds:
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</p>
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<pre>
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node.http.createServer(function (req, res) {
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setTimeout(function () {
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res.sendHeader(200, {"Content-Type": "text/plain"});
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res.sendBody("Hello World");
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res.finish();
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}, 2000);
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}).listen(8000);
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puts("Server running at http://127.0.0.1:8000/");</pre>
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<p>
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To run the server, put the code into a file
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<code>example.js</code> and execute it with the <code>node</code>
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program
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</p>
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<pre class="sh_none">
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% /usr/local/bin/node example.js
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Server running at http://127.0.0.1:8000/</pre>
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<p>
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See the <a href="api.html">API documentation</a> for more
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examples.
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</p>
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<h2 id="audience">Audience</h2>
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<p>This project is for those interested in</p>
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<ul>
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<li>server-side javascript</li>
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<li>developing evented servers</li>
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<li>developing new web frameworks</li>
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</ul>
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<h2 id="about">About</h2>
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<p>
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Node's goal is to provide an easy way to build scalable network
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programs. In the above example, the two second delay does not
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prevent the server from handling new requests. Node tells the
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operating system (through <code>epoll</code>, <code>kqueue</code>,
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<code class="sh_none">/dev/poll</code>, or <code>select</code>)
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that it should be notified when the 2 seconds are up or if a new
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connection is made—then it goes to sleep. If someone new
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connects, then it executes the callback, if the timeout expires,
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it executes the inner callback. Each connection is only a small
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heap allocation.
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</p>
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<p>
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This is in contrast to today's more common model where OS threads
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are employed for concurrency. Thread-based networking
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<a href="http://www.sics.se/~joe/apachevsyaws.html">is</a>
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<a href="http://www.kegel.com/c10k.html">relatively</a>
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<a href="http://bulk.fefe.de/scalable-networking.pdf">inefficient</a>
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<!-- TODO needs links -->
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and very difficult to use.
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Node will show much better memory efficiency under high-loads
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<!-- TODO benchmark -->
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than systems which allocate 2mb thread stacks for each connection.
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Furthermore, users of Node are free from worries of dead-locking
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the process—there are no locks. Almost no function in Node
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directly performs I/O, so the process never blocks. Because
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nothing blocks, less-than-expert programmers are able to develop
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fast systems.
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</p>
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<p>
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Node is similar in design to systems like Ruby's <a
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href="http://rubyeventmachine.com/">Event Machine</a> or Python's <a
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href="http://twistedmatrix.com/">Twisted</a>. Node takes the event
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model a bit further. For example, in other systems there is always
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a blocking call to start the event-loop. Typically one defines
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behavior through callbacks at the beginning of a script and at the
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end starts a server through a call like
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<code>EventMachine::run()</code>. In Node there is no such
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start-the-event-loop call. Node simply enters the event loop after
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executing the input script. Node exits the event loop when there are
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no more callbacks to perform. This behavior is like browser
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javascript—the event loop is hidden from the user.
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</p>
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<p>
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Node's HTTP library has grown out of my difficulties developing and
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working with web servers. For example, streaming data through most
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web frameworks is impossible. Node attempts to correct these
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problems in its HTTP API. Coupled with Node's purely evented
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infrastructure, it makes a good foundation for web libraries or
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frameworks.
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</p>
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<p>
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<i>
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But what about multiple-processor concurrency? Threads are
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necessary to scale programs to multi-core computers.
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</i>
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The name <i>Node</i> gives some hint at how it is envisioned
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being used. Processes are necessary to scale to multi-core
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computers, not memory-sharing threads. The fundamentals of scalable
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systems are fast networking and non-blocking design—the rest
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is message passing. In the future, I'd like Node to be able to
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spawn new processes (probably using the
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<a href="http://www.whatwg.org/specs/web-workers/current-work/">
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Web Workers API
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</a>), but this is something that fits well into the current design.
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</p>
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<h2 id="download">Download</h2>
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<p>
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<a href="http://github.com/ry/node/tree/master">git repo</a>
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</p>
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<p>
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2009.08.27
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<a href="http://s3.amazonaws.com/four.livejournal/20090827/node-0.1.7.tar.gz">node-0.1.7.tar.gz</a>
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</p>
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<h2 id="build">Build</h2>
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<p>
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Node eventually wants to support all POSIX operating systems
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(including Windows with MinGW) but at the moment it is only being
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tested on <b>Linux</b>, <b>Macintosh</b>, and <b>FreeBSD</b>. The
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build system requires Python 2.4 or better. V8, on which Node is
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built, supports only IA-32 and ARM processors. V8 is included in the
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Node distribution. There are no dependencies.
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</p>
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<pre class="sh_none">
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./configure
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make
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make install</pre>
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<p>
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Then have a look at the <a href="api.html">API documentation</a>.
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</p>
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<p>To run the tests</p>
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<pre class="sh_none">make test</pre>
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<h2 id="demo">Demo</h2>
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<p>
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A chat room demo is running at <a
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href="http://chat.tinyclouds.org">chat.tinyclouds.org</a>. The
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source code for the chat room is at <a
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href="http://github.com/ry/node_chat/tree/master">http://github.com/ry/node_chat</a>.
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The chat room is not stable and might occasionally be down.
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</p>
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<h2 id="community">Community</h2>
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<p>
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For help and discussion subscribe to the mailing list at
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<a href="http://groups.google.com/group/nodejs">http://groups.google.com/group/nodejs</a>
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or send an email to <a href="mailto:nodejs+subscribe@googlegroups.com">nodejs+subscribe@googlegroups.com</a>.
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</p>
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<p>
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For real-time discussion, check irc.freenode.net #node.js.
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</p>
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</div>
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</body>
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</html>
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