mirror of
https://github.com/nodejs/node.git
synced 2024-11-29 15:06:33 +01:00
225 lines
6.4 KiB
HTML
225 lines
6.4 KiB
HTML
|
|
<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: inherit; }
|
|
|
|
h1 {
|
|
margin: 2em 0;
|
|
padding: 0px 0px 0px 0px;
|
|
font-size: 51px;
|
|
line-height: 44px;
|
|
font-weight: bold;
|
|
}
|
|
h1 a { color: inherit; }
|
|
|
|
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>. It enables easy development of
|
|
highly concurrent, efficent network programs. For example, this is a
|
|
simple web server which responds with "Hello World" after waiting two
|
|
seconds:
|
|
<pre class="sh_javascript">
|
|
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 little server can handle hundreds of
|
|
concurrent requests while using little CPU or memory—<a
|
|
href="#benchmarks">see benchmarks</a>. The example demonstrates
|
|
efficency that is needed for handling long held "comet" requests.
|
|
|
|
<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
|
|
2mb default stack size on linux (1mb on windows, 64kb on FreeBSD)
|
|
of course this is adjustable
|
|
<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 class="sh_javascript">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 class="sh_javascript">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>
|