flowhttp

flowHttp

Treat node.js http(s) as a simple duplex stream

Install

npm install flowhttp

Basic usage

var flowHttp = require('flowhttp');

// A simple GET request
flowHttp('http://example.com').pipe(process.stdout);

// Upload a file
fs.createReadStream('./file.txt').pipe(flowHttp.post('http://example.com/upload'));

API

flowHttp.request(options)

At the core of the flowHttp module is the flowHttp.request() method. This method performs a basic HTTP or HTTPS request (defaults to GET).

options can be an object or a string. If options is a string, it is automatically parsed with url.parse().

The options argument is identical to the first argument of the http.request() method in the http core module. You should check out that documentation for the most up-to-date info related to your version of node.js.

It returns a flowHttp.Request object which can be used to send data along with the request and receive data from the response. This makes it very easy to read data from any request and optionally write data to a POST or PUT request.

flowHttp.get(options)

One of 4 convenience methods corresponding to the standard HTTP REST verbs. The only difference between this method and flowHttp.request() is that it sets the method to GET and calls req.end() automatically.

flowHttp.post(options)

One of 4 convenience methods corresponding to the standard HTTP REST verbs. The only difference between this method and flowHttp.request() is that it sets the method to POST.

flowHttp.put(options)

One of 4 convenience methods corresponding to the standard HTTP REST verbs. The only difference between this method and flowHttp.request() is that it sets the method to PUT.

flowHttp.del(options)

One of 4 convenience methods corresponding to the standard HTTP REST verbs. The only difference between this method and flowHttp.request() is that it sets the method to DELETE and calls req.end() automatically.

flowHttp(options)

Since most requests are GET requests, the flowHttp.get() method have been aliased for your convenience.

flowHttp.agent

Set this property to http.globalAgent can easily be overwritten:

flowHttp.agent = false; // don't use an agent

For more info about custom agents, see http.Agent.

Class: flowHttp.Request

The Request object is returned by flowHttp.request() and its convenience methods. Request inherits from stream.Duplex.

var duplexRequestStream = flowHttp('http://example.com');

Besides the normal methods and properties avaliable on a duplex stream, the following API have been made available:

request.req

The native http.ClientRequest object.

request.res

The native http.IncomingMessage object. Note that this property will not be available until the response event have been emittet.

request.setHeader(name, value)

An alias for request.req.setHeader().

request.getHeader(name)

An alias for request.req.getHeader().

request.removeHeader(name)

An alias for request.req.removeHeader().

Event 'response'

function (response) {}

Get access to the raw http.IncomingMessage reponse object. This is emitted before any data or end event. You would normally not need to listen for this event unless you need to acceess the response headers or status code.

Event 'data'

function (chunk) {}

Emitted for each chunk of the reponse body.

Event 'end'

function () {}

Emitted when the entire reponse have been received.

Event 'error'

function (err) {}

If an error occurs during the request/reponse cycle, you will get notified here.

Examples

A dead simple GET request piped to STDOUT:

flowHttp('http://example.com').pipe(process.stdout);

Same as above by listening to the emitted events:

var body = '';
flowHttp('http://example.com')
  .on('response', function (res) {
    if (res.headers['some-header'] !== 'some-expected-value')
      res.destroy(); // terminate the request
  })
  .on('data', function (chunk) {
    body += chunk;
  })
  .on('end', function () {
    // output the body returned from the GET example.com reqeust
    console.log(body);
  });

Upload a picture by piping it through a simple POST request and outputting the response to STDOUT:

fs.createReadableStream('./picture.jpg')
  .pipe(flowHttp.post('http://example.com'))
  .pipe(process.stdout);

POST data to the remote server and pipe the response to STDOUT:

var req = flowHttp.post('http://example.com');
req.pipe(process.stdout);
req.write('data to be sent to the server');
red.end(); // call end to send the request

Piping

A very common usage of flowHttp is to pipe the response to a writable stream:

flowHttp('http://example.com').pipe(getWriteableStreamSomehow());

But what if the writeable stream needs access to the http.IncomingMessage object? E.g. to know the HTTP status code or read some of the headers.

To allow for this, a special response event is emittet to all writeable streams attached using the request.pipe() method. Consider the following example:

var util = require('util');
var zlib = require('zlib');
var PassThrough = require('stream').PassThrough;

// Decoder that will check the Conent-Encoding headers and optionally
// decode the body of the HTTP request
var Decoder = function () {
  var decoder = this;
  PassThrough.call(this);

  // Listen for the special `response` event
  this.once('response', function (res) {
    if (res.headers['content-encoding'] === 'gzip') {
      decoder._src.unpipe(decoder);
      decoder._src.pipe(zlib.createGunzip()).pipe(decoder);
    }
  });

  // Record the source of the pipe to be used above
  this.once('pipe', function (src) {
    decoder._src = src;
  });
};
util.inherits(Decoder, PassThrough);

flowHttp('http://example.com').pipe(new Decoder()).pipe(process.stdout);

See the flowhttp-decoder module for a fully working example.

Chaining

If you chain multiple streams using the .pipe() method, you might want to forward the response event down the line. A special readable._forwardFlowHttpResponse() method have been added to the Readable class. This method will therefore be available for all streams that you pipe from.

See the flowhttp-decoder module as an example of how to implement this in your own streams.

Modules supporting flowHttp

• flowhttp-status - Supply a whitelist of HTTP status codes. If the HTTP response doesn't conform to this whitelist, an error event will be emittet on the stream
• flowhttp-decoder - Automatically decode gzipped and deflated responses

License

MIT