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<title>node.js</title>
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<div id="toc">
<ol>
<li><a href="#timers">Timers</a></li>
<li>
<a href="#files">File I/O</a>
<ol>
<li><a href="#file_wrappers">Wrappers</a></li>
<li><a href="#file_file">File</a></li>
</ol>
</li>
<li>
<a href="#tcp">TCP</a>
<ol>
<li><a href="#tcp_server">Server</a></li>
<li><a href="#tcp_connection">Connection</a></li>
</ol>
</li>
<li>
<a href="#http">HTTP</a>
<ol>
<li>
<a href="#http_server">Server</a>
<ol>
<li><a href="#http_server_request">Request</a></li>
<li><a href="#http_server_response">Response</a></li>
</ol>
</li>
<li>
<a href="#http_client">Client</a>
<ol>
<li><a href="#http_client_request">Request</a></li>
<li><a href="#http_client_response">Response</a></li>
</ol>
</li>
</ol>
</li>
<li><a href="#modules">Modules</a></li>
</ol>
</div>
<div id="content">
<h1 id="api">Node API</h1>
<p>
Conventions: Callbacks are object members which are prefixed with
<code>on</code>. All methods and members are camel cased. Constructors
always have a capital first letter.
</p>
<p>
Node supports 3 byte-string encodings: ASCII (<code>"ascii"</code>),
UTF-8 (<code>"utf8"</code>), and raw binary (<code>"raw"</code>).
It uses strings to represent ASCII and UTF-8 encoded data. For
the moment, arrays of integers are used to represent raw binary
data&mdash;this representation is rather inefficient. This will
change in the future, when
<a href="http://code.google.com/p/v8/issues/detail?id=270">
V8 supports Blob objects
</a>.
</p>
<p>The following are global functions:</p>
<dl>
<dt><code>puts(string, callback)</code></dt>
<dd>
Alias for <code>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.
</p>
</dd>
<dt><code>print(string, callback)</code></dt>
<dd>Like <code>puts()</code> but without the trailing new-line.</dd>
<dt><code>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>node.exit(code)</code></dt>
<dd>Immediately ends the process with the specified code.</dd>
</dl>
<h2 id="timers">Timers</h2>
<dl>
<dt><code>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>.
</dd>
<dt><code>clearTimeout(timeoutId)</code></dt>
<dd>Prevents said timeout from triggering.</dd>
<dt><code>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>.
</dd>
<dt><code>clearInterval(intervalId)</code></dt>
<dd>Stops a interval from triggering.</dd>
</dl>
<h2 id="files"><code>node.fs</code></h2>
<p>
File I/O is tricky because there are not simple non-blocking ways
to do it. 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>
<p>
This part of the API is split into two parts: simple wrappers
around standard POSIX file I/O functions and a user-friendly
<code>File</code> object.
</p>
<h3 id="file_wrappers">POSIX Wrappers</h3>
<p>
All POSIX wrappers have a similar form. They return
<code>undefined</code> and have a callback called
<code>on_completion</code> as their last argument. The
<code>on_completion</code> callback may be passed many parameters,
but the first parameter is always an integer indicating the error
status. If the status integer is zero, then the call was successful.
Example:
</p>
<pre>
node.fs.unlink("/tmp/hello", function (status) {
if (status == 0)
puts("successfully deleted /tmp/hello");
});</pre>
<p>
There is no guaranteed ordering to the POSIX wrappers. The
following is very much prone to error
</p>
<pre>
node.fs.rename("/tmp/hello", "/tmp/world");
node.fs.stat("/tmp/world", function (status, stats) {
puts("stats: " + JSON.stringify(stats));
});</pre>
<p>
because it could be that <code>stat()</code> is executed before
the <code>rename()</code>. The correct way to do this, is use the
<code>on_completion</code> callback for <code>rename()</code>
</p>
<pre>
node.fs.rename("/tmp/hello", "/tmp/world", function (status) {
if (status != 0) return;
node.fs.stat("/tmp/world", function (status, stats) {
puts("stats: " + JSON.stringify(stats));
});
});</pre>
<dl>
<dt><code>node.fs.rename(path1, path2, on_completion(status))</code></dt>
<dd> <a href="http://opengroup.org/onlinepubs/007908799/xsh/rename.html">rename(2)</a> </dd>
<dt><code>node.fs.stat(path, on_completion(status, stats))</code></dt>
<dd> <a href="http://opengroup.org/onlinepubs/007908799/xsh/stat.html">stat(2)</a> </dd>
<dt><code>node.fs.unlink(path, on_completion(status))</code></dt>
<dd> <a href="http://opengroup.org/onlinepubs/007908799/xsh/unlink.html">unlink(2)</a> </dd>
<dt><code>node.fs.rmdir(path, on_completion(status))</code></dt>
<dd> <a href="http://opengroup.org/onlinepubs/007908799/xsh/rmdir.html">rmdir(2)</a> </dd>
<dt><code>node.fs.close(fd, on_completion(status))</code></dt>
<dd> <a href="http://opengroup.org/onlinepubs/007908799/xsh/close.html">close(2)</a> </dd>
<dt><code>node.fs.open(path, flags, mode, on_completion(status, fd))</code></dt>
<dd>
<a href="http://opengroup.org/onlinepubs/007908799/xsh/open.html">open(2)</a>
<p>
The constants like <code>O_CREAT</code> are defined at
<code>node.O_CREAT</code>.
</p>
</dd>
<dt><code>node.fs.write(fd, data, position, on_completion(status, written))</code></dt>
<dd>
Write data to the file specified by <code>fd</code>.
<p>
<code>data</code> is either an array of integer (for raw
data) or a string for UTF-8 encoded characters.
</p>
<p>
<code>position</code> refers to the offset from the beginning
of the file where this data should be written. If
<code>null</code>, the data will be written at the current
position.
</p>
<p>See also
<a href="http://opengroup.org/onlinepubs/007908799/xsh/pwrite.html">pwrite(2)</a>
</p>
</dd>
<dt><code>node.fs.read(fd, length, position, encoding, on_completion(status, data))</code></dt>
<dd>
Read data from the file specified by <code>fd</code>.
<p>
<code>length</code> is an integer specifying the number of
bytes to read.
</p>
<p>
<code>position</code> is an integer specifying where to begin
reading from in the file.
</p>
<p>
<code>encoding</code> is either <code>node.UTF8</code>
or <code>node.RAW</code>.
</p>
</dd>
</dl>
<h3 id="file_file"><code>node.fs.File</code></h3>
<p>Easy buffered file object.</p>
<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:
</p>
<pre>
var file = new node.fs.File();
file.open("/tmp/blah", "w+");
file.write("hello");
file.write("world");
file.close();</pre>
<p>
Request queues are local to a single file. If one does
</p>
<pre>
fileA.write("hello");
fileB.write("world");</pre>
<p>
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:
</p>
<pre>
fileA.write("hello", function () {
fileB.write("world");
});</pre>
<dl>
<dt><code>new node.fs.File(options={})</code></dt>
<dd>
Creates a new file object.
<p>
The <code>options</code> argument is optional. It can contain
the following fields
</p>
<ul>
<li><code>fd</code> &mdash; a file descriptor for the file.</li>
<li>
<code>encoding</code> &mdash; how <code>file.read()</code>
should return data. Either <code>"raw"</code> or
<code>"utf8"</code>. Defaults to raw.
</li>
</ul>
</dd>
<dt><code>file.onError = function (method, errno, msg) { }</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>
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>
</dd>
<dt><code>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.
<!-- TODO: Describe mode a+ -->
<code>"a+"</code>
<!-- TODO: Describe mode a+ -->
</p>
<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.
</p>
</dd>
<dt><code>file.read(length, position, on_completion(data))</code></dt>
<dd></dd>
<dt><code>file.write(data, position, on_completion(written))</code></dt>
<dd></dd>
<dt><code>file.close(on_completion())</code></dt>
<dd></dd>
</dl>
<h2 id="tcp"><code>node.tcp</code></h2>
<h3 id="tcp_server"><code>node.tcp.Server</code></h3>
<p>
Here is an example of a echo server which listens for connections
on port 7000
</p>
<pre>
function Echo (socket) {
socket.setEncoding("utf8");
socket.onConnect = function () {
socket.send("hello\r\n");
};
socket.onReceive = function (data) {
socket.send(data);
};
socket.onEOF = function () {
socket.send("goodbye\r\n");
socket.close();
};
}
var server = new node.tcp.Server(Echo, {backlog: 1024});
server.listen(7000, "localhost");</pre>
<dl>
<dt><code>new node.tcp.Server(connection_handler(socket), options={});</code></dt>
<dd>
Creates a new TCP server.
<p>
<code>connection_handler</code> is a callback which is called
on each connection. It is given one argument: an instance of
<code>node.tcp.Connection</code>.
</p>
<p>
<code>options</code> for now only supports one option:
<code>backlog</code> which should be an integer and describes
how large of a connection backlog the operating system should
maintain for this server. The <code>backlog</code> defaults
to 1024.
</p>
</dd>
<dt><code>server.listen(port, host=null)</code></dt>
<dd>
Tells the server to listen for TCP connections to <code>port</code>
and <code>host</code>. Note, <code>host</code> is optional. If
<code>host</code> is not specified the server will accept
connections to any IP address on the specified port.
</dd>
<dt><code>server.close()</code></dt>
<dd> Stops the server from accepting new connections. </dd>
</dl>
<h3 id="tcp_connection"><code>node.tcp.Connection</code></h3>
<p>
This object is used as a TCP client and also as a server-side
socket for <code>node.tcp.Server</code>s.
</p>
<dl>
<dt><code>new node.tcp.Connection()</code></dt>
<dd>Creates a new connection object.</dd>
<dt><code>connection.connect(port, host="127.0.0.1")</code></dt>
<dd>
Opens a connection to the specified <code>port</code> and
<code>host</code>. If the second parameter is omitted, localhost is
assumed.
</dd>
<dt><code>connection.remoteAddress</code></dt>
<dd>
The string representation of the remote IP address. For example,
<code>"74.125.127.100"</code> or <code>"2001:4860:a005::68"</code>.
<p>This member is only present in server-side connections.</p>
</dd>
<dt><code>connection.readyState</code></dt>
<dd>
Either <code>"closed"</code>, <code>"open"</code>, <code>"opening"</code>
<code>"readOnly"</code>, or <code>"writeOnly"</code>.
</dd>
<dt><code>connection.setEncoding(encoding)</code></dt>
<dd>
Sets the encoding (either <code>"utf8"</code> or
<code>"raw"</code>) for data that is received.
</dd>
<dt><code>connection.send(data, encoding="ascii")</code></dt>
<dd>
Sends data on the connection. The data should be eithre an array
of integers (for raw binary) or a string (for utf8 or ascii).
The second parameter specifies the encoding in the case of a
string&mdash;it defaults to ASCII because encoding to UTF8 is
rather slow.
</dd>
<dt><code>connection.close()</code></dt>
<dd>
Half-closes the connection. I.E. sends a FIN packet. It is
possible the server will still send some data. After calling
this <code>readyState</code> will be <code>"readOnly"</code>.
</dd>
<dt><code>connection.fullClose()</code></dt>
<dd>
Close both ends of the connection. Data that is received
after this call is responded to with RST packets. If you don't
know about this, just use <code>close()</code>.
</dd>
<dt><code>connection.forceClose()</code></dt>
<dd>
Ensures that no more I/O activity happens on this socket. Only
necessary in case of errors (parse error or so).
</dd>
<dt><code>connection.onConnect = function () { };</code></dt>
<dd>Call once the connection is established.</dd>
<dt><code>connection.onReceive = function (data) { };</code></dt>
<dd>
Called when data is received on the connection. Encoding of data
is set by <code>connection.setEncoding()</code>.
<code>data</code> will either be a string, in the case of utf8,
or an array of integer in the case of raw encoding.
</dd>
<dt><code>connection.onEOF = function () { };</code></dt>
<dd>
Called when the other end of the connection sends a FIN packet.
<code>onReceive</code> will not be called after this. After
receiving this <code>readyState</code> will be
<code>"writeOnly"</code>. You should probably just call
<code>connection.close()</code> in this callback.
</dd>
<dt><code>connection.onDisconnect = function (had_error) { };</code></dt>
<dd>
Called once the connection is fully disconnected.
<p>
The callback is passed one boolean argument <code>had_error</code>.
This lets one know if the connect was closed due to an error.
(TODO: look up error codes.)
</p>
</dd>
<dt><code>connection.onError = function () { };</code></dt>
<dd>Called on an error.</dd>
</dl>
<h2 id="http"><code>node.http</code></h2>
<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>
<p>
HTTP message headers are represented by an array of 2-element
arrays like this
</p>
<pre>
[ ["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></p>
<h3 id="http_server"><code>node.http.Server</code></h3>
<dl>
<dt><code>new node.http.Server(request_handler, options);</code></dt>
<dd>
<p>Creates a new web server.</p>
<p>
The <code>options</code> argument is optional. The
<code>options</code> argument accepts the same values as the
options argument for <code>node.tcp.Server</code> does.
</p>
<p>
The <code>request_handler</code> is a callback which is made
on each request with a <code>ServerRequest</code> and
<code>ServerResponse</code> arguments.
</p>
</dd>
<dt><code>server.listen(port, hostname)</code></dt>
<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.
</p>
</dd>
<dt><code>server.close()</code></dt>
<dd>
<p>Stops the server from accepting new connections.</p>
</dd>
</dl>
<h3 id="http_server_request"><code>node.http.ServerRequest</code></h3>
<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>request_handler</code> callback.
</p>
<dl>
<dt><code>req.method</code></dt>
<dd>The request method as a string. Read only. Example:
<code>"GET"</code>, <code>"DELETE"</code>.
</dd>
<dt><code>req.uri</code></dt>
<dd> Request URI. (Object.)</dd>
<dt><code>req.uri.anchor</code></dt>
<dt><code>req.uri.query</code></dt>
<dt><code>req.uri.file</code></dt>
<dt><code>req.uri.directory</code></dt>
<dt><code>req.uri.path</code></dt>
<dt><code>req.uri.relative</code></dt>
<dt><code>req.uri.port</code></dt>
<dt><code>req.uri.host</code></dt>
<dt><code>req.uri.password</code></dt>
<dt><code>req.uri.user</code></dt>
<dt><code>req.uri.authority</code></dt>
<dt><code>req.uri.protocol</code></dt>
<dt><code>req.uri.params</code></dt>
<dt>
<code>req.uri.toString()</code>,
<code>req.uri.source</code>
</dt>
<dd>The original URI found in the status line.</dd>
<dt><code>req.headers</code></dt>
<dd>
The request headers expressed as an array of 2-element arrays.
Read only.
</dd>
<dt><code>req.httpVersion</code></dt>
<dd>
The HTTP protocol version as a string. Read only. Examples:
<code>"1.1"</code>, <code>"1.0"</code>
</dd>
<dt><code>req.onBody = function (chunk) { }; </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>
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 decoded.
<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>req.setBodyEncoding()</code>.
</p>
</dd>
<dt><code>req.onBodyComplete = function () { };</code></dt>
<dd>
Callback. Made exactly once for each message. No arguments.
After <code>onBodyComplete</code> is executed
<code>onBody</code> will no longer be called.
</dd>
<dt><code>req.setBodyEncoding(encoding)</code></dt>
<dd>
Set the encoding for the request body. Either <code>"utf8"</code>
or <code>"raw"</code>. Defaults to raw.
</dd>
<dt><code>req.interrupt()</code></dt>
<dd>
Interrupt the request. You will not receive anymore callbacks.
This is useful if, for example someone is streaming up a file but it
is too large and neesd to be stopped. The connection to the client
will be closed immediately.
</dd>
</dl>
<h3 id="http_server_response"><code>node.http.ServerResponse</code></h3>
<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>request_handler</code> callback.
</p>
<dl>
<dt><code>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>404</code>. The second
argument, <code>headers</code>, should be an array of 2-element
arrays, representing the response headers.
<p>Example:</p>
<pre>
var body = "hello world";
res.sendHeader(200, [ ["Content-Length", body.length]
, ["Content-Type", "text/plain"]
]);</pre>
<p>
This method must only be called once on a message and it must
be called before <code>res.finish()</code> is called.
</p>
</dd>
<dt><code>res.sendBody(chunk, encoding="ascii")</code></dt>
<dd>
This method must be called after <code>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.
<p>
If <code>chunk</code> is a string, the second parameter
specifies how to encode it into a byte stream. By default the
<code>encoding</code> is <code>"ascii"</code>.
</p>
</dd>
<dt><code>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>res.finish()</code>, MUST be called on each
response.
</dd>
</dl>
<h3 id="http_client"><code>node.http.Client</code></h3>
<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>
<p> Example of connecting to <code>google.com</code></p>
<pre>
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>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>client.get(path, request_headers);</code></dt>
<dt><code>client.head(path, request_headers);</code></dt>
<dt><code>client.post(path, request_headers);</code></dt>
<dt><code>client.del(path, request_headers);</code></dt>
<dt><code>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>
<p>
Do remember to include the <code>Content-Length</code> header if you
plan on sending a body. If you plan on streaming the body, perhaps
set <code>Transfer-Encoding: chunked</code>.
</p>
<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>req.sendBody()</code>.)
</p>
<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></p>
</dd>
</dl>
<h3 id="http_client_request"><code>node.http.ClientRequest</code></h3>
<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.
</p>
<dl>
<dt><code>req.sendBody(chunk, encoding="ascii")</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>["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>
<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>
</dd>
<dt><code>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>"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.
</p>
</dd>
</dl>
<h3 id="http_client_response"><code>node.http.ClientResponse</code></h3>
<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.
</p>
<dl>
<dt><code>res.statusCode</code></dt>
<dd>The 3-digit HTTP response status code. E.G. <code>404</code>.</dd>
<dt><code>res.httpVersion</code></dt>
<dd>
The HTTP version of the connected-to server. Probably either
<code>"1.1"</code> or <code>"1.0"</code>.
</dd>
<dt><code>res.headers</code></dt>
<dd>The response headers. An Array of 2-element arrays.</dd>
<dt><code>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>res.setBodyEncoding()</code>.
</p>
</dd>
<dt><code>res.onBodyComplete</code></dt>
<dd>
Callback. Made exactly once for each message. No arguments.
After <code>onBodyComplete</code> is executed
<code>onBody</code> will no longer be called.
</dd>
<dt><code>res.setBodyEncoding(encoding)</code></dt>
<dd>
Set the encoding for the response body. Either
<code>"utf8"</code> or <code>"raw"</code>. Defaults to raw.
</dd>
</dl>
<h2 id="modules">Modules</h2>
<p>
Node has a simple module loading system. In Node, files and
modules are in one-to-one correspondence. As an example,
<code>foo.js</code> loads the module <code>mjsunit.js</code>.
</p>
<p>The contents of <code>foo.js</code>:</p>
<pre>
include("mjsunit.js");
function onLoad () {
assertEquals(1, 2);
}</pre>
<p>The contents of <code>mjsunit.js</code>:</p>
<pre>
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>
The module <code>mjsunit.js</code> has exported a function
<code>assertEquals()</code>. <code>mjsunit.js</code> must be
in the same directory as <code>foo.js</code> for
<code>include()</code> to find it. The module path is relative
to the file calling <code>include()</code>.
</p>
<p>
<code>include()</code> inserts the exported objects from the
specified module into the global namespace.
</p>
<p>
Because file loading does not happen instantaneously, and
because Node has a policy of never blocking, the callback
<code>onLoad</code> can be set and will notify the user when the
included modules are loaded. Each file/module can have an
<code>onLoad</code> callback.
</p>
<p>
To export an object, add to the special <code>exports</code>
object. The functions <code>fail</code> and
<code>deepEquals</code> are not exported and remain private to
the module.
</p>
<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>onLoad()</code> callback is made. For example:
</p>
<pre>
var mjsunit = require("mjsunit.js");
function onLoad () {
mjsunit.assertEquals(1, 2);
}</pre>
<p>
<code>include()</code> and <code>require()</code> cannot be
used after <code>onLoad()</code> is called. So put them at the
beginning of your file.
</p>
<p>
Additionally when <code>node.exit()</code> is called or when
a program exits naturally, the function <code>onExit()</code> will be
called for each module (children first).
The <code>onExit()</code> callback cannot perform I/O as the process is
going to forcably exit in several microseconds, however it is a good
hook to perform some constant time checks of the module's state.
It's useful for unit tests.
</p>
<p>
Just to reiterate: <code>onExit()</code>, is not the place to close
files or shutdown servers. The process will exit before they get
performed.
</p>
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