3 To use the HTTP server and client one must `require('http')`.
5 The HTTP interfaces in Node are designed to support many features
6 of the protocol which have been traditionally difficult to use.
7 In particular, large, possibly chunk-encoded, messages. The interface is
8 careful to never buffer entire requests or responses--the
9 user is able to stream data.
11 HTTP message headers are represented by an object like this:
13 { 'content-length': '123',
14 'content-type': 'text/plain',
15 'connection': 'keep-alive',
18 Keys are lowercased. Values are not modified.
20 In order to support the full spectrum of possible HTTP applications, Node's
21 HTTP API is very low-level. It deals with stream handling and message
22 parsing only. It parses a message into headers and body but it does not
23 parse the actual headers or the body.
28 This is an `EventEmitter` with the following events:
32 `function (request, response) { }`
34 Emitted each time there is request. Note that there may be multiple requests
35 per connection (in the case of keep-alive connections).
36 `request` is an instance of `http.ServerRequest` and `response` is
37 an instance of `http.ServerResponse`
39 ### Event: 'connection'
41 `function (socket) { }`
43 When a new TCP stream is established. `socket` is an object of type
44 `net.Socket`. Usually users will not want to access this event. The
45 `socket` can also be accessed at `request.connection`.
49 `function (errno) { }`
51 Emitted when the server closes.
53 ### Event: 'checkContinue'
55 `function (request, response) { }`
57 Emitted each time a request with an http Expect: 100-continue is received.
58 If this event isn't listened for, the server will automatically respond
59 with a 100 Continue as appropriate.
61 Handling this event involves calling `response.writeContinue` if the client
62 should continue to send the request body, or generating an appropriate HTTP
63 response (e.g., 400 Bad Request) if the client should not continue to send the
66 Note that when this event is emitted and handled, the `request` event will
71 `function (request, socket, head) { }`
73 Emitted each time a client requests a http upgrade. If this event isn't
74 listened for, then clients requesting an upgrade will have their connections
77 * `request` is the arguments for the http request, as it is in the request event.
78 * `socket` is the network socket between the server and client.
79 * `head` is an instance of Buffer, the first packet of the upgraded stream, this may be empty.
81 After this event is emitted, the request's socket will not have a `data`
82 event listener, meaning you will need to bind to it in order to handle data
83 sent to the server on that socket.
85 ### Event: 'clientError'
87 `function (exception) { }`
89 If a client connection emits an 'error' event - it will forwarded here.
91 ### http.createServer([requestListener])
93 Returns a new web server object.
95 The `requestListener` is a function which is automatically
96 added to the `'request'` event.
98 ### server.listen(port, [hostname], [callback])
100 Begin accepting connections on the specified port and hostname. If the
101 hostname is omitted, the server will accept connections directed to any
102 IPv4 address (`INADDR_ANY`).
104 To listen to a unix socket, supply a filename instead of port and hostname.
106 This function is asynchronous. The last parameter `callback` will be called
107 when the server has been bound to the port.
110 ### server.listen(path, [callback])
112 Start a UNIX socket server listening for connections on the given `path`.
114 This function is asynchronous. The last parameter `callback` will be called
115 when the server has been bound.
120 Stops the server from accepting new connections.
123 ## http.ServerRequest
125 This object is created internally by a HTTP server -- not by
126 the user -- and passed as the first argument to a `'request'` listener.
128 This is an `EventEmitter` with the following events:
132 `function (chunk) { }`
134 Emitted when a piece of the message body is received.
136 Example: A chunk of the body is given as the single
137 argument. The transfer-encoding has been decoded. The
138 body chunk is a string. The body encoding is set with
139 `request.setEncoding()`.
145 Emitted exactly once for each request. After that, no more `'data'` events
146 will be emitted on the request.
152 Indicates that the underlaying connection was terminated before
153 `response.end()` was called or able to flush.
155 The `err` parameter is always present and indicates the reason for the timeout:
157 `err.code === 'timeout'` indicates that the underlaying connection timed out.
158 This may happen because all incoming connections have a default timeout of 2
161 `err.code === 'aborted'` means that the client has closed the underlaying
162 connection prematurely.
164 Just like `'end'`, this event occurs only once per request, and no more `'data'`
165 events will fire afterwards.
167 Note: `'close'` can fire after `'end'`, but not vice versa.
171 The request method as a string. Read only. Example:
177 Request URL string. This contains only the URL that is
178 present in the actual HTTP request. If the request is:
180 GET /status?name=ryan HTTP/1.1\r\n
181 Accept: text/plain\r\n
184 Then `request.url` will be:
188 If you would like to parse the URL into its parts, you can use
189 `require('url').parse(request.url)`. Example:
191 node> require('url').parse('/status?name=ryan')
192 { href: '/status?name=ryan',
193 search: '?name=ryan',
195 pathname: '/status' }
197 If you would like to extract the params from the query string,
198 you can use the `require('querystring').parse` function, or pass
199 `true` as the second argument to `require('url').parse`. Example:
201 node> require('url').parse('/status?name=ryan', true)
202 { href: '/status?name=ryan',
203 search: '?name=ryan',
204 query: { name: 'ryan' },
205 pathname: '/status' }
215 Read only; HTTP trailers (if present). Only populated after the 'end' event.
217 ### request.httpVersion
219 The HTTP protocol version as a string. Read only. Examples:
221 Also `request.httpVersionMajor` is the first integer and
222 `request.httpVersionMinor` is the second.
225 ### request.setEncoding(encoding=null)
227 Set the encoding for the request body. Either `'utf8'` or `'binary'`. Defaults
228 to `null`, which means that the `'data'` event will emit a `Buffer` object..
233 Pauses request from emitting events. Useful to throttle back an upload.
238 Resumes a paused request.
240 ### request.connection
242 The `net.Socket` object associated with the connection.
245 With HTTPS support, use request.connection.verifyPeer() and
246 request.connection.getPeerCertificate() to obtain the client's
247 authentication details.
251 ## http.ServerResponse
253 This object is created internally by a HTTP server--not by the user. It is
254 passed as the second parameter to the `'request'` event. It is a `Writable Stream`.
256 ### response.writeContinue()
258 Sends a HTTP/1.1 100 Continue message to the client, indicating that
259 the request body should be sent. See the [checkContinue](#event_checkContinue_) event on
262 ### response.writeHead(statusCode, [reasonPhrase], [headers])
264 Sends a response header to the request. The status code is a 3-digit HTTP
265 status code, like `404`. The last argument, `headers`, are the response headers.
266 Optionally one can give a human-readable `reasonPhrase` as the second
271 var body = 'hello world';
272 response.writeHead(200, {
273 'Content-Length': body.length,
274 'Content-Type': 'text/plain' });
276 This method must only be called once on a message and it must
277 be called before `response.end()` is called.
279 If you call `response.write()` or `response.end()` before calling this, the
280 implicit/mutable headers will be calculated and call this function for you.
282 Note: that Content-Length is given in bytes not characters. The above example
283 works because the string `'hello world'` contains only single byte characters.
284 If the body contains higher coded characters then `Buffer.byteLength()`
285 should be used to determine the number of bytes in a given encoding.
286 And Node does not check whether Content-Length and the length of the body
287 which has been transmitted are equal or not.
289 ### response.statusCode
291 When using implicit headers (not calling `response.writeHead()` explicitly), this property
292 controls the status code that will be send to the client when the headers get
297 response.statusCode = 404;
299 After response header was sent to the client, this property indicates the
300 status code which was sent out.
302 ### response.setHeader(name, value)
304 Sets a single header value for implicit headers. If this header already exists
305 in the to-be-sent headers, it's value will be replaced. Use an array of strings
306 here if you need to send multiple headers with the same name.
310 response.setHeader("Content-Type", "text/html");
314 response.setHeader("Set-Cookie", ["type=ninja", "language=javascript"]);
317 ### response.getHeader(name)
319 Reads out a header that's already been queued but not sent to the client. Note
320 that the name is case insensitive. This can only be called before headers get
325 var contentType = response.getHeader('content-type');
327 ### response.removeHeader(name)
329 Removes a header that's queued for implicit sending.
333 response.removeHeader("Content-Encoding");
336 ### response.write(chunk, encoding='utf8')
338 If this method is called and `response.writeHead()` has not been called, it will
339 switch to implicit header mode and flush the implicit headers.
341 This sends a chunk of the response body. This method may
342 be called multiple times to provide successive parts of the body.
344 `chunk` can be a string or a buffer. If `chunk` is a string,
345 the second parameter specifies how to encode it into a byte stream.
346 By default the `encoding` is `'utf8'`.
348 **Note**: This is the raw HTTP body and has nothing to do with
349 higher-level multi-part body encodings that may be used.
351 The first time `response.write()` is called, it will send the buffered
352 header information and the first body to the client. The second time
353 `response.write()` is called, Node assumes you're going to be streaming
354 data, and sends that separately. That is, the response is buffered up to the
357 ### response.addTrailers(headers)
359 This method adds HTTP trailing headers (a header but at the end of the
360 message) to the response.
362 Trailers will **only** be emitted if chunked encoding is used for the
363 response; if it is not (e.g., if the request was HTTP/1.0), they will
364 be silently discarded.
366 Note that HTTP requires the `Trailer` header to be sent if you intend to
367 emit trailers, with a list of the header fields in its value. E.g.,
369 response.writeHead(200, { 'Content-Type': 'text/plain',
370 'Trailer': 'TraceInfo' });
371 response.write(fileData);
372 response.addTrailers({'Content-MD5': "7895bf4b8828b55ceaf47747b4bca667"});
376 ### response.end([data], [encoding])
378 This method signals to the server that all of the response headers and body
379 has been sent; that server should consider this message complete.
380 The method, `response.end()`, MUST be called on each
383 If `data` is specified, it is equivalent to calling `response.write(data, encoding)`
384 followed by `response.end()`.
387 ## http.request(options, callback)
389 Node maintains several connections per server to make HTTP requests.
390 This function allows one to transparently issue requests.
394 - `host`: A domain name or IP address of the server to issue the request to.
395 - `port`: Port of remote server.
396 - `method`: A string specifying the HTTP request method. Possible values:
397 `'GET'` (default), `'POST'`, `'PUT'`, and `'DELETE'`.
398 - `path`: Request path. Should include query string and fragments if any.
399 E.G. `'/index.html?page=12'`
400 - `headers`: An object containing request headers.
401 - `agent`: Controls `Agent` behavior. Possible values:
402 - `undefined` (default): use default `Agent` for this host and port.
403 - `Agent` object: explicitly use the passed in `Agent`.
404 - `false`: explicitly generate a new `Agent` for this host and port. `Agent` will not be re-used.
406 `http.request()` returns an instance of the `http.ClientRequest`
407 class. The `ClientRequest` instance is a writable stream. If one needs to
408 upload a file with a POST request, then write to the `ClientRequest` object.
413 host: 'www.google.com',
419 var req = http.request(options, function(res) {
420 console.log('STATUS: ' + res.statusCode);
421 console.log('HEADERS: ' + JSON.stringify(res.headers));
422 res.setEncoding('utf8');
423 res.on('data', function (chunk) {
424 console.log('BODY: ' + chunk);
428 req.on('error', function(e) {
429 console.log('problem with request: ' + e.message);
432 // write data to request body
437 Note that in the example `req.end()` was called. With `http.request()` one
438 must always call `req.end()` to signify that you're done with the request -
439 even if there is no data being written to the request body.
441 If any error is encountered during the request (be that with DNS resolution,
442 TCP level errors, or actual HTTP parse errors) an `'error'` event is emitted
443 on the returned request object.
445 There are a few special headers that should be noted.
447 * Sending a 'Connection: keep-alive' will notify Node that the connection to
448 the server should be persisted until the next request.
450 * Sending a 'Content-length' header will disable the default chunked encoding.
452 * Sending an 'Expect' header will immediately send the request headers.
453 Usually, when sending 'Expect: 100-continue', you should both set a timeout
454 and listen for the `continue` event. See RFC2616 Section 8.2.3 for more
457 ## http.get(options, callback)
459 Since most requests are GET requests without bodies, Node provides this
460 convenience method. The only difference between this method and `http.request()` is
461 that it sets the method to GET and calls `req.end()` automatically.
466 host: 'www.google.com',
471 http.get(options, function(res) {
472 console.log("Got response: " + res.statusCode);
473 }).on('error', function(e) {
474 console.log("Got error: " + e.message);
479 ## http.getAgent(host, port)
481 `http.request()` uses a special `Agent` for managing multiple connections to
482 an HTTP server. Normally `Agent` instances should not be exposed to user
483 code, however in certain situations it's useful to check the status of the
484 agent. The `http.getAgent()` function allows you to access the agents.
488 `function (response, socket, head) { }`
490 Emitted each time a server responds to a request with an upgrade. If this
491 event isn't being listened for, clients receiving an upgrade header will have
492 their connections closed.
494 A client server pair that show you how to listen for the `upgrade` event using `http.getAgent`:
496 var http = require('http');
497 var net = require('net');
499 // Create an HTTP server
500 var srv = http.createServer(function (req, res) {
501 res.writeHead(200, {'Content-Type': 'text/plain'});
504 srv.on('upgrade', function(req, socket, upgradeHead) {
505 socket.write('HTTP/1.1 101 Web Socket Protocol Handshake\r\n' +
506 'Upgrade: WebSocket\r\n' +
507 'Connection: Upgrade\r\n' +
510 socket.ondata = function(data, start, end) {
511 socket.write(data.toString('utf8', start, end), 'utf8'); // echo back
515 // now that server is running
516 srv.listen(1337, '127.0.0.1', function() {
519 var agent = http.getAgent('127.0.0.1', 1337);
526 'Connection': 'Upgrade',
527 'Upgrade': 'websocket'
531 var req = http.request(options);
534 agent.on('upgrade', function(res, socket, upgradeHead) {
535 console.log('got upgraded!');
544 By default set to 5. Determines how many concurrent sockets the agent can have open.
548 An array of sockets currently in use by the Agent. Do not modify.
552 A queue of requests waiting to be sent to sockets.
556 ## http.ClientRequest
558 This object is created internally and returned from `http.request()`. It
559 represents an _in-progress_ request whose header has already been queued. The
560 header is still mutable using the `setHeader(name, value)`, `getHeader(name)`,
561 `removeHeader(name)` API. The actual header will be sent along with the first
562 data chunk or when closing the connection.
564 To get the response, add a listener for `'response'` to the request object.
565 `'response'` will be emitted from the request object when the response
566 headers have been received. The `'response'` event is executed with one
567 argument which is an instance of `http.ClientResponse`.
569 During the `'response'` event, one can add listeners to the
570 response object; particularly to listen for the `'data'` event. Note that
571 the `'response'` event is called before any part of the response body is received,
572 so there is no need to worry about racing to catch the first part of the
573 body. As long as a listener for `'data'` is added during the `'response'`
574 event, the entire body will be caught.
578 request.on('response', function (response) {
579 response.on('data', function (chunk) {
580 console.log('BODY: ' + chunk);
584 // Bad - misses all or part of the body
585 request.on('response', function (response) {
586 setTimeout(function () {
587 response.on('data', function (chunk) {
588 console.log('BODY: ' + chunk);
593 This is a `Writable Stream`.
594 Note: Node does not check whether Content-Length and the length of the body
595 which has been transmitted are equal or not.
597 This is an `EventEmitter` with the following events:
599 ### Event: 'continue'
603 Emitted when the server sends a '100 Continue' HTTP response, usually because
604 the request contained 'Expect: 100-continue'. This is an instruction that
605 the client should send the request body.
609 `function (response) { }`
611 Emitted when a response is received to this request. This event is emitted only once. The
612 `response` argument will be an instance of `http.ClientResponse`.
615 ### request.write(chunk, encoding='utf8')
617 Sends a chunk of the body. By calling this method
618 many times, the user can stream a request body to a
619 server--in that case it is suggested to use the
620 `['Transfer-Encoding', 'chunked']` header line when
621 creating the request.
623 The `chunk` argument should be an array of integers
626 The `encoding` argument is optional and only
627 applies when `chunk` is a string.
630 ### request.end([data], [encoding])
632 Finishes sending the request. If any parts of the body are
633 unsent, it will flush them to the stream. If the request is
634 chunked, this will send the terminating `'0\r\n\r\n'`.
636 If `data` is specified, it is equivalent to calling `request.write(data, encoding)`
637 followed by `request.end()`.
641 Aborts a request. (New since v0.3.8.)
644 ## http.ClientResponse
646 This object is created when making a request with `http.request()`. It is
647 passed to the `'response'` event of the request object.
649 The response implements the `Readable Stream` interface.
653 `function (chunk) { }`
655 Emitted when a piece of the message body is received.
662 Emitted exactly once for each message. No arguments. After
663 emitted no other events will be emitted on the response.
669 Indicates that the underlaying connection was terminated before
670 `end` event was emitted.
671 See [http.ServerRequest](#http.ServerRequest)'s `'close'` event for more
674 ### response.statusCode
676 The 3-digit HTTP response status code. E.G. `404`.
678 ### response.httpVersion
680 The HTTP version of the connected-to server. Probably either
682 Also `response.httpVersionMajor` is the first integer and
683 `response.httpVersionMinor` is the second.
687 The response headers object.
689 ### response.trailers
691 The response trailers object. Only populated after the 'end' event.
693 ### response.setEncoding(encoding=null)
695 Set the encoding for the response body. Either `'utf8'`, `'ascii'`, or `'base64'`.
696 Defaults to `null`, which means that the `'data'` event will emit a `Buffer` object..
700 Pauses response from emitting events. Useful to throttle back a download.
702 ### response.resume()
704 Resumes a paused response.