coreygrunewald / clients

HttpClient, StringClient, and JsonClient extracted from restify

restify-clients

HttpClient, StringClient, and JsonClient extracted from restify

This module contains HTTP clients extracted from restify.

• JsonClient - sends and expects application/json
• StringClient - sends url-encoded request and expects text/plain
• HttpClient - thin wrapper over node's http/https libraries

The idea being that if you want to support "typical" control-plane REST APIs, you probably want the JsonClient, or if you're using some other serialization (like XML) you'd write your own client that extends the StringClient. If you need streaming support, you'll need to do some work on top of the HttpClient, as StringClient and friends buffer requests/responses.

All clients support retry with exponential backoff for getting a TCP connection; they do not perform retries on 5xx error codes like previous versions of the restify client. You can set retry to false to disable this logic altogether. Also, all clients support a connectTimeout field, which is use on each retry. The default is not to set a connectTimeout, so you end up with the node.js socket defaults.

Getting Started

Install the module with: npm install restify-clients

Usage

Client API

There are actually three separate clients shipped in restify:

• JsonClient: sends and expects application/json
• StringClient: sends url-encoded request and expects text/plain
• HttpClient: thin wrapper over node's http/https libraries

The idea being that if you want to support "typical" control-plane REST APIs, you probably want the JsonClient, or if you're using some other serialization (like XML) you'd write your own client that extends the StringClient. If you need streaming support, you'll need to do some work on top of the HttpClient, as StringClient and friends buffer requests/responses.

All clients support retry with exponential backoff for getting a TCP connection; they do not perform retries on 5xx error codes like previous versions of the restify client. You can set retry to false to disable this logic altogether. Also, all clients support a connectTimeout field, which is use on each retry. The default is not to set a connectTimeout, so you end up with the node.js socket defaults.

Here's an example of hitting the Joyent CloudAPI:

var restify = require('restify');

// Creates a JSON client
var client = restify.createJsonClient({
  url: 'https://us-east-1.api.joyent.com'
});


client.basicAuth('$login', '$password');
client.get('/my/machines', function(err, req, res, obj) {
  assert.ifError(err);

  console.log(JSON.stringify(obj, null, 2));
});

As a short-hand, a client can be initialized with a string-URL rather than an options object:

var restify = require('restify');

var client = restify.createJsonClient('https://us-east-1.api.joyent.com');

Note that all further documentation refers to the "short-hand" form of methods like get/put/del which take a string path. You can also pass in an object to any of those methods with extra params (notably headers):

var options = {
  path: '/foo/bar',
  headers: {
    'x-foo': 'bar'
  },
  retry: {
    'retries': 0
  },
  agent: false
};

client.get(options, function(err, req, res) { .. });

If you need to interpose additional headers in the request before it is sent on to the server, you can provide a synchronous callback function as the signRequest option when creating a client. This is particularly useful with node-http-signature, which needs to attach a cryptographic signature of selected outgoing headers. If provided, this callback will be invoked with a single parameter: the outgoing http.ClientRequest object.

JsonClient

The JSON Client is the highest-level client bundled with restify; it exports a set of methods that map directly to HTTP verbs. All callbacks look like function(err, req, res, [obj]), where obj is optional, depending on if content was returned. HTTP status codes are not interpreted, so if the server returned 4xx or something with a JSON payload, obj will be the JSON payload. err however will be set if the server returned a status code >= 400 (it will be one of the restify HTTP errors). If obj looks like a RestError:

{
  "code": "FooError",
  "message": "some foo happened"
}

then err gets "upconverted" into a RestError for you. Otherwise it will be an HttpError.

createJsonClient(options)

var client = restify.createJsonClient({
  url: 'https://api.us-east-1.joyent.com',
  version: '*'
});

API Options:

Name	Type	Description
accept	String	Accept header to send
audit	Boolean	Enable Audit logging
auditor	Function	Function for Audit logging
connectTimeout	Number	Amount of time to wait for a socket
requestTimeout	Number	Amount of time to wait for the request to finish
dtrace	Object	node-dtrace-provider handle
gzip	Object	Will compress data when sent using content-encoding: gzip
headers	Object	HTTP headers to set in all requests
log	Object	bunyan instance
retry	Object	options to provide to node-retry;"false" disables retry; defaults to 4 retries
signRequest	Function	synchronous callback for interposing headers before request is sent
url	String	Fully-qualified URL to connect to
userAgent	String	user-agent string to use; restify inserts one, but you can override it
version	String	semver string to set the accept-version
followRedirects	Boolean	Follow redirects from server
maxRedirects	Number	Maximum number of redirects to follow

get(path, callback)

Performs an HTTP get; if no payload was returned, obj defaults to {} for you (so you don't get a bunch of null pointer errors).

client.get('/foo/bar', function(err, req, res, obj) {
  assert.ifError(err);
  console.log('%j', obj);
});

head(path, callback)

Just like get, but without obj:

client.head('/foo/bar', function(err, req, res) {
  assert.ifError(err);
  console.log('%d -> %j', res.statusCode, res.headers);
});

post(path, object, callback)

Takes a complete object to serialize and send to the server.

client.post('/foo', { hello: 'world' }, function(err, req, res, obj) {
  assert.ifError(err);
  console.log('%d -> %j', res.statusCode, res.headers);
  console.log('%j', obj);
});

put(path, object, callback)

Just like post:

client.put('/foo', { hello: 'world' }, function(err, req, res, obj) {
  assert.ifError(err);
  console.log('%d -> %j', res.statusCode, res.headers);
  console.log('%j', obj);
});

del(path, callback)

del doesn't take content, since you know, it should't:

client.del('/foo/bar', function(err, req, res) {
  assert.ifError(err);
  console.log('%d -> %j', res.statusCode, res.headers);
});

StringClient

StringClient is what JsonClient is built on, and provides a base for you to write other buffering/parsing clients (like say an XML client). If you need to talk to some "raw" HTTP server, then StringClient is what you want, as it by default will provide you with content uploads in application/x-www-form-url-encoded and downloads as text/plain. To extend a StringClient, take a look at the source for JsonClient. Effectively, you extend it, and set the appropriate options in the constructor and implement a write (for put/post) and parse method (for all HTTP bodies), and that's it.

createStringClient(options)

var client = restify.createStringClient({
  url: 'https://example.com'
})

get(path, callback)

Performs an HTTP get; if no payload was returned, data defaults to '' for you (so you don't get a bunch of null pointer errors).

client.get('/foo/bar', function(err, req, res, data) {
  assert.ifError(err);
  console.log('%s', data);
});

head(path, callback)

Just like get, but without data:

client.head('/foo/bar', function(err, req, res) {
  assert.ifError(err);
  console.log('%d -> %j', res.statusCode, res.headers);
});

post(path, object, callback)

Takes a complete object to serialize and send to the server.

client.post('/foo', { hello: 'world' }, function(err, req, res, data) {
  assert.ifError(err);
  console.log('%d -> %j', res.statusCode, res.headers);
  console.log('%s', data);
});

put(path, object, callback)

Just like post:

client.put('/foo', { hello: 'world' }, function(err, req, res, data) {
  assert.ifError(err);
  console.log('%d -> %j', res.statusCode, res.headers);
  console.log('%s', data);
});

del(path, callback)

del doesn't take content, since you know, it should't:

client.del('/foo/bar', function(err, req, res) {
  assert.ifError(err);
  console.log('%d -> %j', res.statusCode, res.headers);
});

HttpClient

HttpClient is the lowest-level client shipped in restify, and is basically just some sugar over the top of node's http/https modules (with HTTP methods like the other clients). It is useful if you want to stream with restify. Note that the event below is unfortunately named result and not response (because Event 'response' is already used).

client = restify.createClient({
  url: 'http://127.0.0.1'
});

client.get('/str/mcavage', function(err, req) {
  assert.ifError(err); // connection error

  req.on('result', function(err, res) {
    assert.ifError(err); // HTTP status code >= 400

    res.body = '';
    res.setEncoding('utf8');
    res.on('data', function(chunk) {
      res.body += chunk;
    });

    res.on('end', function() {
      console.log(res.body);
    });
  });
});

Or a write:

client.post(opts, function(err, req) {
  assert.ifError(connectErr);

  req.on('result', function(err, res) {
    assert.ifError(err);
    res.body = '';
    res.setEncoding('utf8');
    res.on('data', function(chunk) {
      res.body += chunk;
    });

    res.on('end', function() {
      console.log(res.body);
    });
  });

  req.write('hello world');
  req.end();
});

Note that get/head/del all call req.end() for you, so you can't write data over those. Otherwise, all the same methods exist as JsonClient/StringClient.

One wishing to extend the HttpClient should look at the internals and note that read and write probably need to be overridden.

Proxy

There are several options for enabling a proxy for the http client. The following options are available to set a proxy url:

// Set the proxy option in the client configuration
restify.createClient({
    proxy: 'http://127.0.0.1'
});

From environment variables:

$ export HTTPS_PROXY = 'https://127.0.0.1'
$ export HTTP_PROXY = 'http://127.0.0.1'

There is an option to disable the use of a proxy on a url basis or for all urls. This can be enabled by setting an environment variable.

Don't proxy requests to any urls

$ export NO_PROXY='*'

Don't proxy requests to localhost

$ export NO_PROXY='127.0.0.1'

Don't proxy requests to localhost on port 8000

$ export NO_PROXY='localhost:8000'

Don't proxy requests to multiple IPs

$ export NO_PROXY='127.0.0.1, 8.8.8.8'

Note: The url being requested must match the full hostname in the proxy configuration or NO_PROXY environment variable. DNS lookups are not performed to determine the IP address of a hostname.

basicAuth(username, password)

Since it hasn't been mentioned yet, this convenience method (available on all clients), just sets the Authorization header for all HTTP requests:

client.basicAuth('mark', 'mysupersecretpassword');

Upgrades

If you successfully negotiate an Upgrade with the HTTP server, an upgradeResult event will be emitted with the arguments err, res, socket and head. You can use this functionality to establish a WebSockets connection with a server. For example, using the watershed library:

var ws = new Watershed();
var wskey = ws.generateKey();
var options = {
  path: '/websockets/attach',
  headers: {
    connection: 'upgrade',
    upgrade: 'websocket',
    'sec-websocket-key': wskey,
  }
};
client.get(options, function(err, res, socket, head) {
  res.once('upgradeResult', function(err2, res2, socket2, head2) {
    var shed = ws.connect(res2, socket2, head2, wskey);
    shed.on('text', function(msg) {
      console.log('message from server: ' + msg);
      shed.end();
    });
    shed.send('greetings program');
  });
});

Contributing

Add unit tests for any new or changed functionality. Ensure that lint and style checks pass.

To start contributing, install the git pre-push hooks:

make githooks

Before committing, run the prepush hook:

make prepush

If you have style errors, you can auto fix whitespace issues by running:

make codestyle-fix

License

Copyright (c) 2015 Alex Liu

Licensed under the MIT license.