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<title>node.js</title>
<body onload="sh_highlightDocument();">
<div id="toc">
<ol>
<li><a href="#benchmarks">Benchmarks</a></li>
<li><a href="#download">Download</a></li>
<li><a href="#build">Build</a></li>
<li><a href="#api">API</a>
<ol>
<li><a href="#timers">Timers</a>
<li><a href="#files">File I/O</a>
<li><a href="#tcp">TCP</a>
<ol>
<li><a href="#tcp_server">Server</a>
<li><a href="#tcp_connection">Connection</a>
</ol>
<li><a href="#http">HTTP</a>
<ol>
<li><a href="#http_server">Server</a>
<ol>
<li><a href="#http_server_request">Request</a>
<li><a href="#http_server_response">Response</a>
</ol>
<li><a href="#http_client">Client</a>
<ol>
<li><a href="#http_client_request">Request</a>
<li><a href="#http_client_response">Response</a>
</ol>
</ol>
<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">Purely asynchronous server-side I/O for <a
href="http://code.google.com/p/v8/">V8 javascript</a>.
<p>Analogy
<pre>
Python : Twisted
Ruby : Event Machine
Javascript : Node</pre>
<p>This is an example of a web server written with Node which responds with
"Hello World" after waiting two seconds:
<pre class="sh_javascript">new node.http.Server(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> See <a href="#api">the API documentation</a> for more examples.
<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="benchmarks">Benchmarks</h2>
<p> TODO
<h2 id="download">Download</h2>
<p> TODO
<h2 id="build">Build</h2>
<pre>./configure
make
make install</pre>
<h2 id="api">API</h2>
<p>Conventions: Callbacks are object members which are prefixed with
<code class="sh_javascript">on</code>. All methods and members are camel cased. Constructors
always have a capital first letter.
<p>Node uses strings to represent ASCII or UTF-8 encoded data. For the
moment, arrays of integers are used to represent raw binary data&mdash;this
representation is rather inefficient. In the future, <a
href="http://code.google.com/p/v8/issues/detail?id=270">when V8 natively supports binary
Blob objects</a>, Node will use them.
<p>The following are some global general purpose functions:</p>
<dl>
<dt><code class="sh_javascript">puts(string, callback)</code></dt>
<dd>
Alias for <code class="sh_javascript">stdout.puts()</code>.
Outputs the <code>string</code> and a trailing new-line to <code>stdout</code>.
<p>The <code>callback</code> argument is optional and mostly useless: it will
notify the user when the operation has completed. Everything in node is
asynchronous; <code>puts()</code> is no exception. This might seem ridiculous
but, if for example, one is piping <code>stdout</code> into an NFS file,
<code>printf()</code> will block from network latency.
There is an internal queue for <code>puts()</code> output, so you can be assured that
output will be displayed in the order it was called.
</dd>
<dt><code class="sh_javascript">print(string, callback)</code></dt>
<dd>Like <code>puts()</code> but without the trailing new-line.</dd>
<dt><code class="sh_javascript">node.debug(string)</code></dt>
<dd>A synchronous output function. Will <i>block</i> the process and output the
string immediately to stdout. Use with care.</dd>
<dt><code class="sh_javascript">node.exit(code)</code></dt>
<dd>Immediately ends the process with the specified code.</dd>
</dl>
<h3 id="timers">Timers</h3>
<dl>
<dt><code class="sh_javascript">setTimeout(callback, delay)</code></dt>
<dd> To schedule execution of <code>callback</code> after <code>delay</code>
milliseconds. Returns a <code>timeoutId</code> for possible use with
<code>clearTimeout()</code>.
<dt><code class="sh_javascript">clearTimeout(timeoutId)</code></dt>
<dd> Prevents said timeout from triggering.
<dt><code class="sh_javascript">setInterval(callback, delay)</code></dt>
<dd> To schedule the repeated execution of <code>callback</code> every
<code>delay</code> milliseconds. Returns a <code>intervalId</code> for
possible use with <code>clearInterval()</code>.
<dt><code class="sh_javascript">clearInterval(intervalId)</code></dt>
<dd> Stops a interval from triggering. </dd>
</dl>
<h3 id="files">node.fs</h3>
<p>Because there are not non-blocking ways to do it, asynchronous file I/O is
tricky. Node handles file I/O by employing <a
href="http://software.schmorp.de/pkg/libeio.html">an internal thread pool</a>
to execute file system calls.
<p>Internal request queues exist for each file object so that multiple commands
can be issued at once without worry that they will be executed out-of-order.
Thus the following is safe:
<pre class="sh_javascript">
var file = new node.fs.File();
file.open("/tmp/blah", "w+");
file.write("hello");
file.write("world");
file.close();</pre>
<p>
It's important to understand that the request queues are local to a single file.
If one does
<pre class="sh_javascript">fileA.write("hello");
fileB.write("world");</pre>
it could be that <code>fileB</code> gets written to before <code>fileA</code>
is written to.
If a certain operation order is needed involving multiple files, use the
completion callbacks:
<pre class="sh_javascript">fileA.write("hello", function () {
fileB.write("world");
});</pre>
<dl>
<dt><code class="sh_javascript">new node.fs.File</code></dt>
<dd>Creates a new file object. </dd>
<dt><code class="sh_javascript">file.onError</code></dt>
<dd>Callback. This is called internally anytime an error occurs with this
file. There are three arguments: the method name, the POSIX errno, and a
string describing the error.
<p>Example</p>
<pre class="sh_javascript">
var path = "/some/path/that/doesnt/exist";
var file = new node.fs.File();
file.onError = function (method, errno, msg) {
stderr.puts("An error occurred calling " + method);
stderr.puts(msg);
node.exit(1);
}
file.open(path, "w+")
</pre>
<dt><code class="sh_javascript">file.open(path, mode, on_completion)</code></dt>
<dd>Opens the file at <code>path</code>.
<p><code>mode</code> is a string:
<code>"r"</code> open for reading and writing.
<code>"r+"</code> open for only reading.
<code>"w"</code> create a new file for reading and writing; if it
already exists truncate it.
<code>"w+"</code> create a new file for writing only; if it already
exists truncate it.
<code>"a"</code> create a new file for writing and reading. Writes
append to the end of the file.
<code>"a+"</code>
<p>The <code>on_completion</code> is a callback that is made without
arguments when the operation completes. It is optional
If an error occurred the <code>on_completion</code> callback will not be
called, but the <code>file.onError</code> will be called.
</dd>
<dt><code class="sh_javascript">file.read(length, position, on_completion)</code></dt>
<dd>
</dd>
<dt><code class="sh_javascript">file.write(data, position, on_completion)</code></dt>
<dd>
</dd>
<dt><code class="sh_javascript">file.close(on_completion)</code></dt>
<dd>
</dd>
</dl>
<h4>File System Operations</h4>
<dl>
<dt><code class="sh_javascript">node.fs.rename(path1, path2, on_completion)</code></dt>
<dd>
</dd>
<dt><code class="sh_javascript">node.fs.stat(path1, on_completion)</code></dt>
<dd>
</dd>
</dl>
<h3 id="tcp"><code>node.tcp</code></h3>
<h4 id="tcp_server"><code>node.tcp.Server</code></h4>
<h4 id="tcp_connection"><code>node.tcp.Connection</code></h4>
<h3 id="http"><code>node.http</code></h3>
<p>The HTTP interfaces here are designed to support many features
of the protocol which have been traditionally difficult to handle. In
particular, large, possibly chunked, messages. The interface is
careful to never buffer entire requests or responses&mdash;the user is able
to stream data.
<p> HTTP message headers are represented by an array of 2-element arrays like this
<pre class="sh_javascript">
[ ["Content-Length", "123"]
, ["Content-Type", "text/plain"]
, ["Connection", "keep-alive"]
, ["Accept", "*/*"]
]
</pre>
<p><i>Dictionary-like objects are popularly used to represent HTTP headers but they are
an incorrect abstraction. It is rare, but possible, to have multiple header lines
with the same field. Setting multiple cookies in a single response, for
example, can only be done with multiple <code>Cookie</code> lines.</i>
<h4 id="http_server"><code class="sh_javascript">node.http.Server</code></h4>
<dl>
<dt><code class="sh_javascript">new node.http.Server(request_handler, options);</code></dt>
<dd>
<p>Creates a new web server.
<p>
The <code>options</code> argument is optional.
The <code
class="sh_javascript">options</code> argument accepts the same values
as the options argument for <code
class="sh_javascript">node.tcp.Server</code> does.
<p>The <code class="sh_javascript">request_handler</code> is a
callback which is made on each request with a
<code>ServerRequest</code> and
<code>ServerResponse</code> arguments.
</dd>
<dt><code class="sh_javascript">server.listen(port, hostname)</code>
<dd>
<p>Begin accepting connections on the specified port and hostname. If the
hostname is omitted, the server will accept connections directed to any
address.
</dd>
<dt><code class="sh_javascript">server.close()</code>
<dd>
<p>Stops the server from accepting new connections.
</dd>
</dl>
<h4 id="http_server_request"><code class="sh_javascript">node.http.ServerRequest</code></h4>
<p> This object is created internally by a HTTP server&mdash;not by the user.
It is passed to the user as the first argument to the <code
class="sh_javascript">request_handler</code> callback.
<dl>
<dt><code class="sh_javascript">req.method</code>
<dd>The request method as a string. Read only. Example: <code class="sh_javascript">"GET"</code>,
<code class="sh_javascript">"DELETE"</code>.</dd>
<dt><code class="sh_javascript">req.uri</code>
<dd> Request URI. (Object.)
<dt><code>req.uri.anchor</code>
<dt><code>req.uri.query</code>
<dt><code>req.uri.file</code>
<dt><code>req.uri.directory</code>
<dt><code>req.uri.path</code>
<dt><code>req.uri.relative</code>
<dt><code>req.uri.port</code>
<dt><code>req.uri.host</code>
<dt><code>req.uri.password</code>
<dt><code>req.uri.user</code>
<dt><code>req.uri.authority</code>
<dt><code>req.uri.protocol</code>
<dt><code>req.uri.queryKey</code>
<dt><code>req.uri.toString()</code>, <code>req.uri.source</code>
<dd> The original URI found in the status line.
<dt><code class="sh_javascript">req.headers</code>
<dd>The request headers expressed as an array of 2-element arrays. Read only.
<dt><code class="sh_javascript">req.httpVersion</code></dt>
<dd>The HTTP protocol version as a string. Read only. Examples: <code class="sh_javascript">"1.1"</code>,
<code class="sh_javascript">"1.0"</code>
<dt><code class="sh_javascript">req.onBody</code></dt>
<dd>Callback. Should be set by the user to be informed of when a piece
of the message body is received. Example:
<pre class="sh_javascript">
req.onBody = function (chunk) {
puts("part of the body: " + chunk);
};
</pre>
A chunk of the body is given as the single argument. The transfer-encoding
has been removed.
<p>The body chunk is either a String in the case of UTF-8 encoding or an
array of numbers in the case of raw encoding. The body encoding is set with
<code class="sh_javascript">req.setBodyEncoding()</code>.
<dt><code class="sh_javascript">req.onBodyComplete</code></dt>
<dd>Callback. Made exactly once for each message. No arguments. After
<code class="sh_javascript">onBodyComplete</code> is executed <code class="sh_javascript">onBody</code> will no longer be called.
</dd>
<dt><code class="sh_javascript">req.setBodyEncoding(encoding)</code></dt>
<dd>
Set the encoding for the request body. Either <code class="sh_javascript">"utf8"</code> or
<code class="sh_javascript">"raw"</code>. Defaults to raw.
</dl>
<h4 id="http_server_response"><code class="sh_javascript">node.http.ServerResponse</code></h4>
<p> This object is created internally by a HTTP server&mdash;not by the user.
It is passed to the user as the second argument to the <code
class="sh_javascript">request_handler</code> callback.
<dl>
<dt><code class="sh_javascript">res.sendHeader(statusCode, headers)</code></dt>
<dd>
Sends a response header to the request. The status code is a 3-digit
HTTP status code, like <code class="sh_javascript">404</code>. The second argument,
<code class="sh_javascript">headers</code>, should be an array of 2-element arrays,
representing the response headers.
<p>Example:
<pre class="sh_javascript">
var body = "hello world";
res.sendHeader(200, [ ["Content-Length", body.length]
, ["Content-Type", "text/plain"]
]);
</pre>
This method must only be called once on a message and it must be called
before <code class="sh_javascript">res.finish()</code> is called.
</dd>
<dt><code class="sh_javascript">res.sendBody(chunk)</code></dt>
<dd>
This method must be called after <code class="sh_javascript">sendHeader</code> was called. It
sends a chunk of the response body. This method may be called multiple
times to provide successive parts of the body.
</dd>
<dt><code class="sh_javascript">res.finish()</code></dt>
<dd>
This method signals that all of the response headers and body has been
sent; that server should consider this message complete.
The method, <code class="sh_javascript">res.finish()</code>, MUST be called on each response.
</dl>
<h4 id="http_client"><code class="sh_javascript">node.http.Client</code></h4>
<p> An HTTP client is constructed with a server address as its argument, the
returned handle is then used to issue one or more requests. Depending on the
server connected to, the client might pipeline the requests or reestablish the
connection after each connection.
<i>Currently the implementation does not pipeline requests.</i>
<p> Example of connecting to <code>google.com</code>
<pre class="sh_javascript">
var google = new node.http.Client(80, "google.com");
var req = google.get("/");
req.finish(function (res) {
puts("STATUS: " + res.statusCode);
puts("HEADERS: " + JSON.stringify(res.headers));
res.setBodyEncoding("utf8");
res.onBody = function (chunk) {
puts("BODY: " + chunk);
};
});
</pre>
<dl>
<dt><code class="sh_javascript">new node.http.Client(port, host);</code></dt>
<dd> Constructs a new HTTP client. <code>port</code> and <code>host</code>
refer to the server to be connected to. A connection is not established until a
request is issued.
</dd>
<dt><code class="sh_javascript">client.get(path, request_headers);</code></dt>
<dt><code class="sh_javascript">client.head(path, request_headers);</code></dt>
<dt><code class="sh_javascript">client.post(path, request_headers);</code></dt>
<dt><code class="sh_javascript">client.del(path, request_headers);</code></dt>
<dt><code class="sh_javascript">client.put(path, request_headers);</code></dt>
<dd> Issues a request; if necessary establishes connection.
<p>
<code>request_headers</code> is optional.
<code>request_headers</code> should be an array of 2-element arrays.
Additional request headers might be added internally by Node.
Returns a <code>ClientRequest</code> object.
<p>Important: the request is not complete. This method only sends the
header of the request. One needs to call <code>req.finish()</code> to finalize
the request and retrieve the response. (This sounds convoluted but it provides
a chance for the user to stream a body to the server with <code
class="sh_javascript">req.sendBody()</code>.)
<p><i> <code>GET</code> and
<code>HEAD</code> requests normally are without bodies but HTTP does not forbid
it, so neither do we.</i>
</dl>
<h4 id="http_client_request"><code class="sh_javascript">node.http.ClientRequest</code></h4>
<p>This object is created internally and returned from the request methods of a
<code>node.http.Client</code>. It represents an <i>in-progress</i> request
whose header has already been sent.
<dl>
<dt><code class="sh_javascript">req.sendBody(chunk, encoding)</code></dt>
<dd> Sends a sucessive peice of the body. By calling this method many times,
the user can stream a request body to a server&mdash;in that case it is
suggested to use the <code class="sh_javascript">["Transfer-Encoding",
"chunked"]</code> header line when creating the request.
<p>The <code>chunk</code> argument should be an array of integers or a string.
<p>The <code>encoding</code> argument is optional and only applies when
<code>chunk</code> is a string. The encoding argument should be either
<code>"utf8"</code> or <code>"ascii"</code>. By default the body uses ASCII
encoding, as it is faster.
<p> TODO
<dt><code class="sh_javascript">req.finish(response_handler)</code></dt>
<dd> Finishes sending the request. If any parts of the body are
unsent, it will flush them to the socket. If the request is chunked, this
will send the terminating <code class="sh_javascript">"0\r\n\r\n"</code>.
<p>The parameter <code>response_handler</code> is a user-supplied callback which will
be executed exactly once when the server response headers have been received.
The <code>response_handler</code> callback is executed with one argument: a
<code>ClientResponse</code> object.
</dl>
<h4 id="http_client_response"><code class="sh_javascript">node.http.ClientResponse</code></h4>
<p>This object is created internally and passed to the
<code>response_handler</code> callback (is given to the client in
<code>req.finish</code> function). The response object appears exactly as the
header is completely received but before any part of the response body has been
read.
<dl>
<dt><code class="sh_javascript">res.statusCode</code></dt>
<dd>The 3-digit HTTP response status code. E.G. <code class="sh_javascript">404</code>.</dd>
<dt><code class="sh_javascript">res.httpVersion</code></dt>
<dd>The HTTP version of the connected-to server. Probably either
<code class="sh_javascript">"1.1"</code> or
<code class="sh_javascript">"1.0"</code>.
</dd>
<dt><code class="sh_javascript">res.headers</code></dt>
<dd>The response headers. An Array of 2-element arrays.</dd>
<dt><code class="sh_javascript">res.onBody</code></dt>
<dd>Callback. Should be set by the user to be informed of when a piece
of the response body is received.
A chunk of the body is given as the single argument. The transfer-encoding
has been removed.
<p>The body chunk is either a <code>String</code> in the case of UTF-8
encoding or an array of numbers in the case of raw encoding. The body
encoding is set with <code class="sh_javascript">res.setBodyEncoding()</code>.
<dt><code class="sh_javascript">res.onBodyComplete</code></dt>
<dd>Callback. Made exactly once for each message. No arguments. After
<code class="sh_javascript">onBodyComplete</code> is executed
<code class="sh_javascript">onBody</code> will no longer be called.
</dd>
<dt><code class="sh_javascript">res.setBodyEncoding(encoding)</code></dt>
<dd>
Set the encoding for the response body. Either <code class="sh_javascript">"utf8"</code> or
<code class="sh_javascript">"raw"</code>. Defaults to raw.
</dd>
</dl>
<h3 id="modules">Modules</h3>
<p>Node has a simple module loading system. In Node, files and modules are
in one-to-one correspondence.
<p> As an example,
<code class="sh_javascript">foo.js</code> loads the module <code class="sh_javascript">mjsunit.js</code>.
<p>The contents of <code class="sh_javascript">foo.js</code>:
<pre class="sh_javascript">
include("mjsunit");
function onLoad () {
assertEquals(1, 2);
}
</pre>
<p>The contents of <code class="sh_javascript">mjsunit.js</code>:
<pre class="sh_javascript">
function fail (expected, found, name_opt) {
// ...
}
function deepEquals (a, b) {
// ...
}
exports.assertEquals = function (expected, found, name_opt) {
if (!deepEquals(found, expected)) {
fail(expected, found, name_opt);
}
};
</pre>
<p>Here the module <code class="sh_javascript">mjsunit.js</code> has exported the function
<code class="sh_javascript">assertEquals()</code>. <code class="sh_javascript">mjsunit.js</code> must be in the
same directory as <code class="sh_javascript">foo.js</code> for <code class="sh_javascript">include()</code> to find it.
The module path is relative to the file calling <code class="sh_javascript">include()</code>.
The module path does not include filename extensions like <code class="sh_javascript">.js</code>.
<p> <code class="sh_javascript">include()</code> inserts the exported objects
from the specified module into the global namespace.
<p> Because file loading does not happen instantaneously, and because Node
has a policy of never blocking, the callback <code
class="sh_javascript">onLoad</code> can be set and will notify the user
when all the included modules are loaded. Each file/module can have an <code
class="sh_javascript">onLoad</code> callback.
<p>To export an object, add to the special <code>exports</code> object.
<p> The functions <code class="sh_javascript">fail</code> and <code class="sh_javascript">deepEquals</code> are not
exported and remain private to the module.
<p> <code>require()</code> is like <code>include()</code> except does not
polute the global namespace. It returns a namespace object. The exported objects
can only be guaranteed to exist after the <code class="sh_javascript">onLoad()</code> callback is
made. For example:
<pre class="sh_javascript">
var mjsunit = require("mjsunit");
function onLoad () {
mjsunit.assertEquals(1, 2);
}
</pre>
<p> <code class="sh_javascript">include()</code> and <code class="sh_javascript">require()</code> cannot be used after
<code class="sh_javascript">onLoad()</code> is called. So put them at the beginning of your file.
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