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nodejs/spec/index.html
2009-03-05 14:22:09 +01:00

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<html lang=en-US-x-hixie>
<head>
<title>Node API</title>
<link href="specification.css" rel=stylesheet>
<body class=draft>
<div class=head>
<!--
<p><a class=logo href="http://www.whatwg.org/" rel=home><img alt=WHATWG
src="../../../images/logo"></a></p>
-->
<h1>Node API</h1>
<h2 class="no-num no-toc"
id=draft-recommendation-mdash-date-01-jan-1>Draft</h2>
<dl>
<dt>This version:
<dd><a href="index.html">http://tinyclouds.org/node</a>
</dl>
<p class=copyright>&copy; Copyright 2009 Ryan Dahl</p>
<p class=copyright>You are granted a license to use, reproduce and create
derivative works of this document.</p>
</div>
<hr>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p>This specification defines a javascript API for creating
servers and clients based around an event loop. It is provided to document
Node's interface and provide a specification for similar efforts.
<h2 class="no-num no-toc" id=contents>Table of contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="index.html#introduction"><span class=secno>1 </span>Introduction</a>
<ul class=toc>
<li><a href="index.html#the-event-loop"><span class=secno>1.1 </span>The event loop</a>
<li><a href="index.html#execution-context"><span class=secno>1.2 </span>Execution context</a>
</ul>
<li><a href="index.html#http_server"><span class=secno>2 </span>HTTP Server</a>
<li><a href="index.html#tcp_client"><span class=secno>3 </span>TCP Client</a>
<li><a href="index.html#timers"><span class=secno>4 </span>Timers</a>
</ul>
<!--end-toc-->
<hr>
<h2 id=introduction><span class=secno>1 </span>Introduction</h2>
<p>This specification defines an API for creating evented servers and
clients in javascript. It can be considered documentation for the Node
project and will be versioned with that software. However, in places the
API is only a specification and does not reflect Node's
behavior&mdash;there I will try to note the difference.
<p>Unless otherwise noted, all functions can be considered
non-blocking. Non-blocking means that program execution will continue
without waiting for some I/O event (be that network or device).
<h3 id=the-event-loop><span class=secno>1.1 </span>The event loop</h3>
<p>The program is run event loop. There are no concurrent
operations. As long as there are pending events the program will continue
running. If however there arn't any pending callbacks waiting for
something to happen, the program will exit.
<p>Only one callback is executed at a time.
<h3 id=execution-context><span class=secno>1.2 </span>Execution context</h3>
<p>Global data is shared between callbacks.
<p>
<code>spawn()</code> to start a new context/event loop?
<h2 id=http_server><span class=secno>2 </span>HTTP Server</h2>
<h2 id=tcp_client><span class=secno>3 </span>TCP Client</h2>
<pre class=idl>[Constructor(in String host, in String port)]
interface <dfn id=tcpclient>TCPClient</dfn> {
readonly attribute String <a href="index.html#host">host</a>;
readonly attribute String <a href="index.html#port">port</a>;
// ready state
const unsigned short CONNECTING = 0;
const unsigned short OPEN = 1;
const unsigned short CLOSED = 2;
readonly attribute long readyState;
// networking
attribute Function <a href="index.html#onopen">onopen</a>;
attribute Function <a href="index.html#onread">onread</a>;
attribute Function <a href="index.html#onclose">onclose</a>;
void write(in String data);
void disconnect();
};</pre>
<dl>
<dt><code>TCPClient(host, port)</code></dt>
<dd>
<p>When a <code><a href="#connection0">TCPClient</a></code> object is
created, the the interpreter must try to establish a connection.
If the <code>host</code> parameter is not an IP address it
will be looked up using the DNS.
</dd>
<dt><code>write(data)</code></dt>
<dd>
<p>Transmits data using the connection. If the connection is not yet
established, it must raise an <code>INVALID_STATE_ERR</code> exception.
<p><code>write(null)</code> sends an EOF to the peer. Further writing
is disabled. However the <code>onread</code> callback may still
be executed.
</dd>
<dt><code>disconnect()</code></dt>
<dd>
<p>Closes the connection, if it is open. If the connection is already
closed, it does nothing. Closing the connection causes a
<code>onclose</code> callback to be made and the
<code><a href="#readystate0">readyState</a></code> attribute's value to
change to <code>CLOSED</code>.
Note that a connection might not be closed instantaniously. In the
case of secure connection some "goodbye" transmission might be sent.
</dd>
</dl>
</p><p>The <dfn id="readystate0"><code>readyState</code></dfn> attribute
represents the state of the connection. When the object is created it must
be set to <code>CONNECTING</code>.
<p id="onopen">Once a connection is established, the <code
>readyState</a></code>
attribute's value must be changed to <code>OPEN</code>, and the
<code>onopen</code> callback will be made.
<p id="onread">When data is received, the <code>onread</code> callback
will be made with a single parameter: a <code>String</code> containing a
chunk of data. The user does not have the ability to control how much data
is received nor the ability to stop the input besides disconnecting.
<!-- conf crit for this
statement is in the various protocol-specific sections below. -->
<p id="onclose">When the connection is closed, the <code
>readyState</a></code>
attribute's value must be changed to <code>CLOSED</code>, and the <code
>onclose</a></code> callback
will be made.
<h2 id=timers><span class=secno>4 </span>Timers</h2>
<p>Timers allow one to schedule an event at a later date.
There are four globally exposed functions
<code>setTimeout</code>,
<code>clearTimeout</code>,
<code>setInterval</code>, and
<code>clearInterval</code>.
These functions work similarly
<a href="http://www.w3.org/TR/Window/#window-timers">as in the browser</a> except that
the <code>timerID</code> and <code>intervalID</code> do not necessarily have
type <code>long</code> but are rather opaque objects.
<dl>
<dt><code>setTimeout(function, milliseconds)</code></dt>
<dd>
<p>This method calls the function once after a specified number of
milliseconds elapses, until canceled by a call to <code>clearTimeout</code>.
The methods returns a <code>timerID</code> which may be used in a
subsequent call to <code>clearTimeout</code> to cancel the callback.
</dd>
<dt><code>setInterval(function, milliseconds)</code></dt>
<dd>
<p>This method calls the function every time a specified number of
milliseconds elapses, until canceled by a call to <code>clearInterval</code>.
The methods returns a <code>intervalID</code> which may be used in a
subsequent call to <code>clearInterval</code> to cancel the interval.
</dd>
<dt><code>clearTimeout(timerID)</code></dt>
<dd>
<p>Cancels a timeout that was set with the <code>setTimeout</code>
method.
</dd>
<dt><code>clearInterval(intervalID)</code></dt>
<dd>
<p>Cancels an interval that was set with the <code>setInterval</code> method.
</dd>
</dl>