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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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<div id="toc">
<ol>
<li><a href="#audience">Audience</a></li>
<li><a href="#about">About</a></li>
<li><a href="#download">Download</a></li>
<li><a href="#build">Build</a></li>
<li><a href="#demo">Demo</a></li>
<li><a href="#community">Community</a></li>
<li><a href="api.html">Documentation</a></li>
</ol>
</div>
<div id="content">
<h1><a href="http://tinyclouds.org/node">Node</a></h1>
<p id="introduction">
Purely event-based I/O for
<a href="http://code.google.com/p/v8/">V8 javascript</a>.
</p>
<p>
An example of a web server written with Node which responds with
"Hello World" after waiting two seconds:
</p>
<pre>
node.http.createServer(function (req, res) {
setTimeout(function () {
res.sendHeader(200, [["Content-Type", "text/plain"]]);
res.sendBody("Hello World");
res.finish();
}, 2000);
}).listen(8000);
puts("Server running at http://127.0.0.1:8000/");</pre>
<p>
To run the server, put the code into a file
<code>example.js</code> and execute it with the <code>node</code>
program
</p>
<pre class="sh_none">
% /usr/local/bin/node example.js
Server running at http://127.0.0.1:8000/</pre>
<p>
See the <a href="api.html">API documentation</a> for more
examples.
</p>
<h2 id="audience">Audience</h2>
<p>This project is for those interested in</p>
<ul>
<li>server-side javascript</li>
<li>developing evented servers</li>
<li>developing new web frameworks</li>
</ul>
<h2 id="about">About</h2>
<p>
Node's goal is to provide an easy way to build scalable network
programs. In the above example, the 2 second delay does not
prevent the server from handling new requests. Node tells the
operating system (through <code>epoll</code>, <code>kqueue</code>,
<code class="sh_none">/dev/poll</code>, or <code>select</code>)
that it should be notified when the 2 seconds are up or if a new
connection is made—then it goes to sleep. If someone new
connects, then it executes the callback, if the timeout expires,
it executes the inner callback. Each connection is only a small
heap allocation.
</p>
<p>
This is in contrast to today's more common model where OS threads
are employed for concurrency. Thread-based networking
<a href="http://www.sics.se/~joe/apachevsyaws.html">is</a>
<a href="http://www.kegel.com/c10k.html">relatively</a>
<a href="http://bulk.fefe.de/scalable-networking.pdf">inefficient</a>
<!-- TODO needs links -->
and very difficult to use.
Node will show much better memory efficiency under high-loads
<!-- TODO benchmark -->
than systems which allocate 2mb thread stacks for each connection.
Furthermore, users of Node are free from worries of dead-locking
the process—there are no locks. No function in Node
directly performs I/O, so the process never blocks. Because
nothing blocks, less-than-expert programmers are able to develop
fast systems.
</p>
<p>
Node is similar in design to systems like Ruby's
<a href="http://rubyeventmachine.com/">Event Machine</a>
or Python's <a href="http://twistedmatrix.com/">Twisted</a>.
Node takes the event model a bit further. For example, in other
systems there is always a blocking call to start the event-loop.
Typically one defines behavior through callbacks at the beginning
of a script and at the end starts a server through a call like
<code>EventMachine::run()</code>. In Node it works differently.
By default Node enters the event loop after executing the input
script. Node exits the event loop when there are no more callbacks
to perform. Like in traditional browser javascript, the event loop
is hidden from the user.
</p>
<p>
Node's HTTP API has grown out of my difficulties developing and
working with web servers. For example, streaming data through
most web frameworks is impossible. Or the oft-made false
assumption that all message headers have unique fields. Node
attempts to correct these and other problems in its API. Coupled
with Node's purely evented infrastructure, it will make a more
comprehensive foundation for future web libraries/frameworks.
</p>
<p>
<i>
But what about multiple-processor concurrency? Threads are
necessary to scale programs to multi-core computers.
</i>
The name <i>Node</i> should give some hint at how it is envisioned
being used. Processes are necessary to scale to multi-core
computers, not memory-sharing threads. The fundamentals of scalable
systems are fast networking and non-blocking design—the rest
is message passing. In the future, I'd like Node to be able to
spawn new processes (probably using the
<a href="http://www.whatwg.org/specs/web-workers/current-work/">
Web Workers API
</a>), but this is something that fits well into the current design.
</p>
<h2 id="download">Download</h2>
<p>
<a href="http://github.com/ry/node/tree/master">git repo</a>
</p>
<ul>
<li>
2009.08.01
<a href="http://s3.amazonaws.com/four.livejournal/20090801/node-0.1.2.tar.gz">node-0.1.2.tar.gz</a>
</li>
<li>
2009.07.27
<a href="http://s3.amazonaws.com/four.livejournal/20090727/node-0.1.1.tar.gz">node-0.1.1.tar.gz</a>
</li>
<li>
2009.06.30
<a href="http://s3.amazonaws.com/four.livejournal/20090630/node-0.1.0.tar.gz">node-0.1.0.tar.gz</a>
</li>
<li>
2009.06.24
<a href="http://s3.amazonaws.com/four.livejournal/20090624/node-0.0.6.tar.gz">node-0.0.6.tar.gz</a>
</li>
<li>
2009.06.18
<a href="http://s3.amazonaws.com/four.livejournal/20090618/node-0.0.5.tar.gz">node-0.0.5.tar.gz</a>
</li>
<li>
2009.06.13
<a href="http://s3.amazonaws.com/four.livejournal/20090613/node-0.0.4.tar.gz">node-0.0.4.tar.gz</a>
</li>
<li>
2009.06.11
<a href="http://s3.amazonaws.com/four.livejournal/20090611/node-0.0.3.tar.gz">node-0.0.3.tar.gz</a>
</li>
<li>
2009.05.31
<a href="http://s3.amazonaws.com/four.livejournal/20090531/node-0.0.2.tar.gz">node-0.0.2.tar.gz</a>
</li>
<li>
2009.05.27
<a href="http://s3.amazonaws.com/four.livejournal/20090527/node-0.0.1.tar.gz">node-0.0.1.tar.gz</a>
</li>
</ul>
<h2 id="build">Build</h2>
<p>
Node eventually wants to support all POSIX operating systems
(including Windows with MinGW) but at the moment it is only being
tested on <b>Linux</b>, <b>Macintosh</b>, and <b>FreeBSD</b>. The
build system requires Python 2.4 or better. V8, on which Node is
built, supports only IA-32 and ARM processors. V8 is included in the
Node distribution. There are no dependencies.
</p>
<pre class="sh_none">
./configure
make
make install</pre>
<p>
Then have a look at the <a href="api.html">API documentation</a>.
</p>
<p>To run the tests</p>
<pre class="sh_none">make test</pre>
<h2 id="demo">Demo</h2>
<p>
A chat room demo is running at <a
href="http://chat.tinyclouds.org">chat.tinyclouds.org</a>. The
source code for the chat room is at <a
href="http://github.com/ry/node_chat/tree/master">http://github.com/ry/node_chat</a>.
The chat room is not stable and might occasionally be down.
</p>
<h2 id="community">Community</h2>
<p>
For help and discussion subscribe to the mailing list at
<a href="http://groups.google.com/group/nodejs">http://groups.google.com/group/nodejs</a>
or send an email to <a href="mailto:nodejs+subscribe@googlegroups.com">nodejs+subscribe@googlegroups.com</a>.
</p>
<p>
For real-time discussion, check irc.freenode.net #node.js.
</p>
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