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Add webpage. Very incomplete.

v0.7.4-release
Ryan 16 years ago
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<html>
<style>
body {
background: #22252a;
color: #eee;
font-size: 16pt;
line-height: 150%;
font-family: times, Times New Roman, times-roman, georgia, serif;
}
#content {
max-width: 30em;
margin: 0 0 5em 10em;
}
#toc {
position: fixed;
top: 2em;
left: 0;
width: 10em;
}
#toc ol {
list-style: none;
margin: 0;
padding: 0;
padding-left: 1em;
}
#toc ol li {
margin: 0;
padding: 0;
}
#toc a { color: #777; }
h1, h2, h3 { color: #9a2; }
h1 {
margin: 2em 0;
padding: 0px 0px 0px 0px;
font-size: 51px;
line-height: 44px;
font-weight: bold;
}
h2 {
margin: 2em 0;
font-size: inherit;
line-height: inherit;
font-weight: bold;
}
h3 {
margin: 1em 0;
font-size: inherit;
line-height: inherit;
font-weight: inherit;
}
pre, code {
font-family: monospace;
font-size: 14pt;
}
a { color: #cd5; text-decoration: none; }
a:hover { text-decoration: underline; }
</style>
<title>node.js</title>
<body>
<div id="toc">
<ol>
<li><a href="#motivation">Motivation</a></li>
<li><a href="#benchmarks">Benchmarks</a></li>
<li><a href="#download">Download</a></li>
<li><a href="#install">Build</a></li>
<li><a href="#api">API</a>
<ol>
<li><a href="#timers">Timers</a>
<li><a href="#files">File System</a>
<li><a href="#tcp">TCP</a>
<li><a href="#http">HTTP</a>
<li><a href="#modules">Modules</a>
</ol>
</li>
</ol>
</div>
<div id="content">
<h1><a href="http://tinyclouds.org/node">Node</a></h1>
<p id="introduction"> Node is a purely evented I/O framework for <a
href="#">V8 javascript</a>. Its goal is to enable easy development of
highly concurrent, small footprint programs. For example, this is a
simple web server which responds with "Hello World" after waiting two
seconds:
<pre>
node.http.server(function (msg) {
setTimeout(function () {
msg.sendHeader(200, [["Content-Type", "text/plain"]]);
msg.sendBody("Hello World");
msg.finish();
}, 2000);
}).listen(8000, "localhost");
</pre>
<p> While one request is waiting the server will continue to accept and
serve other requests. This is accomplished without threads and is quite
efficient: handling hundreds of concurrent requests while using
little CPU or memory&mdash;<a href="#benchmarks">see benchmarks</a>.
The example might seem esoteric but similar behavior
is required to implement, for example, "comet" servers.
<p> Node is free to <a href="#download">download</a>, <a
href="#api">use</a>, and <a href="#modules">build upon</a>.</p>
<h2 id="motivation">Motivation</h2>
<ol>
<li>Evented programming makes sense
<ol>
<li>difference between blocking/non-blocking design
<li>latency figures
<li>purely evented interfaces rule out a lot of stupidity
</ol>
<li>Evented programs are more efficient
<ol>
<li>pthread stack size
<li>context switching benchmark
<li>Apache vs. Nginx
<li>event machine vs mongrel (neverblock)
</ol>
<li>The appropriateness of Javascript
<ol>
<li>No I/O
<li>No Threads
<li>Good compiler
<li>Universality of the language
</ol>
</ol>
Threads are a bad model.
<p>
<a href="http://duartes.org/gustavo/blog/post/what-your-computer-does-while-you-wait">I/O latency</a>
<pre>
l1 cache ~ 3
l2 cache ~ 14
ram ~ 250
disk ~ 41000000
network ~ 240000000
</pre>
<p> Javascript is without I/O. In the browser the DOM provides I/O,
but non-browser javascript interpreters have only non-standardized
functions to allow them print to console or access the network.
<p> Javascript is without the concept of threads.
<p> Contemporary computer infrastructure has two irreplaceable
languages: C and Javascript. C is the language of operating systems.
POSIX, the universal operating system API, is defined in C. So while you
can interface with operating systems in Java and Haskell, those
languages access must make system calls in C. Similarly, Javascript is
the language of the web operating system. In place of POSIX is the
DOM. You can wrap Javascript, you can compile to Javascript, but in the
end browsers must be interfaced with in Javascript. Portable low-level
systems tend to be written in C and portable web-level systems are
written in Javascript.
<h3>Evented vs Threaded Servers</h3>
<p> There are many methods to write internet servers but they can
fundamentally be divided into two camps: evented and threaded; non-blocking
and blocking. A blocking server accepts a connection and launches a new
thread to handle the connection. Because the concurrency is handled by
the thread scheduler, a blocking server can make function calls which
preform full network requests.
<pre>var response = db.execute("SELECT * FROM table");
// do something</pre>
<p> An evented server manages its concurrency itself. All connections
are handled in a single thread and callbacks are executed on certain
events: "socket 23 is has data to read", "socket 65's write buffer is
empty". An evented server executes small bits of code but never
<i>blocks</i> the process. In the evented world callbacks are used
instead of functions
<pre>db.execute("SELECT * FROM table", function (response) {
// do something
});</pre>
<h2 id="benchmarks">Benchmarks</h2>
<h2 id="download">Download</h2>
<h2 id="build">Build</h2>
<pre>configure
make
make install</pre>
<h2 id="api">Application Programming Interface</h2>
<p> The node executable should be given an argument pointing to a
javascript file.
<h3 id="timers">Timers</h3>
<p>The timer API is the same as in the browser. The functions
<code>setTimeout, setInterval, cancleTimeout, and cancleInterval</code>
<h3 id="files">File System</h3>
<h3 id="tcp">TCP</h3>
<h3 id="http">HTTP</h3>
<h3 id="modules">Modules</h3>
</body>
</html>
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