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166 lines
5.4 KiB
166 lines
5.4 KiB
<html>
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<style>
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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="style.css">
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<link type="text/css" rel="stylesheet" href="sh_vim-dark.css">
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<title>node.js</title>
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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>
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<li><a href="#about">About</a>
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<li><a href="#download">Download</a>
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<li><a href="#build">Build</a>
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<li><a href="api.html">Documentation</a>
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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">Purely event-based I/O for <a
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href="http://code.google.com/p/v8/">V8 javascript</a>.
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<p>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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<pre>
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new node.http.Server(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/");
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</pre>
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<p> To run the server, put the code into a file <code>example.js</code>
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and execute it with the <code>node</code> program
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<pre class="sh_none">% /usr/local/bin/node example.js
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Server running at http://127.0.0.1:8000/
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</pre>
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<p> See the <a href="api.html">API documentation</a> for more examples.
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<h2 id=audience>Audience</h2>
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<p>This project is for those interested in
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<ul>
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<li>server-side javascript
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<li>developing evented servers
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<li>developing new web frameworks
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</ul>
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<h2 id=about>About</h2>
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<p> Node's goal is to provide an easy way to build scalable network
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programs.
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In the above example, the 2 second delay does not prevent the server from
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handling new requests.
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Node tells the operating system (through
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<code>epoll</code>,
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<code>kqueue</code>,
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<code class="sh_none">/dev/poll</code>,
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or <code>select</code>)
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that it should be notified when the 2 seconds are up or if a new connection
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is made—then it goes to sleep. If someone new connects, then it
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executes the callback, if the timeout expires, it executes the inner
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callback. Each connection is only a small heap allocation.
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<p>This is in contrast to today's more common model
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where OS threads are employed for concurrency. But 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
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very
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difficult
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to
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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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Users of Node are free from worries of dead-locking the
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process—there are no locks. In fact, there aren't even blocking
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functions. Because nothing blocks, Node can be given to less-than-export
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programmers to build servers.
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<p>Node is similar to systems like
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Ruby's <a href="http://rubyeventmachine.com/">Event Machine</a>
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or
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Python's <a href="http://twistedmatrix.com/">Twisted</a>.
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But Node takes the mode event-based API further.
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In other systems, there is always a blocking call to start the event-loop.
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Typically one sets up behavior through callbacks and at the end starts the
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server through a call like <code>EventMachine::run()</code>. In Node,
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there is no such thing. By default Node enters the event loop after
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executing the input script. Node exits the event loop when there are no more
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callbacks to perform.
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<p>Node's HTTP API has grown out of my difficulties developing
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and working with web servers. For example, streaming data through most web
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frameworks is difficult or impossible. Or like the oft-made false
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assumption that all message headers have unique fields. Node attempts to
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correct these and other problems in its API.
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Coupled with Node's purely evented infrastructure, it will make a solid
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foundation for future frameworks.
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<p> <i>But what about multiple-processor concurrency? Threads are necessary
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to scale programs to multi-core computers.</i> The name <i>Node</i> should
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give some hint at how it is envisioned being used. Processes are necessary
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to scale to multi-core computers, not memory-sharing threads. The
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fundamentals of scalable systems are fast networking and non-blocking
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design—the rest is message passing. In the future, I'd like Node to
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to be able to spawn new processes (probably using the <a
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href="http://www.whatwg.org/specs/web-workers/current-work/">Web Workers
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API</a>), but this is something that fits well into the current design.
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<h2 id="download">Download</h2>
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<p><a href="http://github.com/ry/node/tree/master">The git repo</a>
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<ul>
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<li> 2009.05.27 <a
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href="http://s3.amazonaws.com/four.livejournal/20090527/node-0.0.1.tar.gz">node-0.0.1.tar.gz</a>
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(2.8mb)
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</ul>
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<h2 id="build">Build</h2>
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<p>Node eventually wants to support all POSIX operating systems (including
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Windows with MinGW) but at the moment it is only being tested on
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<b>Linux</b>,
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<b>Macintosh</b>, and
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<b>FreeBSD</b>. The build system requires Python. V8, on which
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Node is 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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<pre class="sh_none">
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./configure
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make
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make install
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</pre>
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<p> Then have a look at the <a href="api.html">API documentation</a>.
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<p>To run the tests
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<pre class="sh_none">
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./configure --debug
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make test
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</pre>
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</body>
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</html>
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