connect-rest

connect-rest is a featureful very easy-to-use middleware for connect for building REST APIs. The library has a stunning feature list beyond basic rest functionality.

Just a few examples: (far from incomplete):

• execution branches: a single service can have multiple paths and a single incoming request can invoke multiple services
• versioning: rest services can be versioned via many ways
• regular expressions: path description can be given using regular expression
• parameter mappings: path matchings can be bound as parameters
• service discovery: built-in rest service allowing one to discover what rest services are available in general or for a given version
• "reflective" publishing: by providing a single object, its methods will be published as rest services automatically by simple logic
• dynamic API protection by Protectors
• Multiple contexts for flexible orchestrating
• customizable HTTP-layer management: HTTP status code, mime-types, headers, minifying can be set at service and execution level
• async services: a rest service can call back asynchronously when the answer is made
• monitoring/measuring: every rest service execution can be enabled for measurement to be collected and populated internally or for external monitoring solutions

!Note: connect-rest's concept is - as for integration - to provide a connect plugin and to be a framework for your rest services carrying only about content and business logic, nothing else. However, in case of need for interoperability, the need might cause you to use only the path-related features alone. This can be done using dispatchers.

Usage

The connect-rest is a simple, yet powerful middleware for connect, inspired by restify. The aim is to give a really feature-rich tool allowing you to focus on the business logic only.

Installation

$ npm install connect-rest

Features:

• Quick setup
• Assign
• Path description
• Versioning
• Rest functions
• Customize HTTP response
• Customize answers of REST functions
• API_KEY management
• Unprotected rest service
• Protector
• Context
• Orchestrating the contexts
• Discover services
• Prototype services
• Logging
• Reflective publishing
• Domain support
• Answering async rest requests
• Dispatchers
• Monitoring
• More examples
• License
• Changelog

Quick setup

// requires connect and connect-rest middleware
var connect = require('connect');
var rest = require('connect-rest');

// sets up connect and adds other middlewares to parse query, parameters, content and session
// use the ones you need
var connectApp = connect();
	.use( connect.query() )
	.use( connect.session( { ... } ) )
	.use( connect.urlencoded() )
	.use( connect.json() )
;

// initial configuration of connect-rest. all-of-them are optional.
// default context is /api, all services are off by default
var options = {
	apiKeys: [ '849b7648-14b8-4154-9ef2-8d1dc4c2b7e9' ], // to set up api-key restriction
	discoverPath: 'discover', // activates discovery service
	protoPath: 'proto', // activates prototype service
	logger:{ name: 'your appname', level: 'info' }, // activates logger
	context: '/api' // general context used for URIs of connect-rest
};

// adds connect-rest middleware to connect
connectApp.use( rest.rester( options ) );

// defines a few sample rest services
rest.get('/books/:title/:chapter', functionN0 );

rest.post( { path: '/make', version: '>=1.0.0' }, functionN1 );

rest.post( [ '/act', '/do' ], functionN2 );

rest.post( [ { path: '/shake', version: '>=2.0.0' }, { path: '/twist', version: '>=2.1.1' } ], functionN3 );

Back to Feature list

Assign

direct binding

You can assign your rest modules by specifying the needed http request functions: head, get, post, put, delete.

Example:

function service( request, content, callback ){
	console.log( 'Received headers:' + JSON.stringify( request.headers ) );
	console.log( 'Received parameters:' + JSON.stringify( request.parameters ) );
	console.log( 'Received JSON object:' + JSON.stringify( content ) );
	callback(null, 'ok');
}
rest.post( [ { path: '/shake', version: '>=2.0.0' }, { path: '/twist', version: '>=2.1.1' } ], service );

assign function

Other way to assign is to use the assign function directly.

Example:

function service( request, content, callback ){
	...
}
// bind the service funciont to all http request types
rest.assign( '*', [ { path: '/shake', version: '>=2.0.0' }, { path: '/twist', version: '>=2.1.1' } ], service );
...
// bind the service funciont to only the given http request types
rest.assign( ['head','get','post'], [ { path: '/shake', version: '>=2.0.0' }, { path: '/twist', version: '>=2.1.1' } ], service );

parameters

After each assign function you might need to pass the followings:

• a path description
• a function to be called.

Path description

connect-rest supports many options to be used as path description.

Named parameters

rest.get('/books/:title', functionN0 );

or

rest.get('/books/:title/:chapter', functionN0 );

You can define parametrized paths for services to accept REST variables from the caller. In this case, whatever string is after the 'books', will be interpret as variable(s) and passed to the service function via the request object.

So sending a get request to the uri '/api/books/AliceInWonderland/1', will result the following request object:

{"headers": ...,"parameters":{"title":"AliceInWonderland", "chapter": "1"}}

Optional parameter

rest.post('/store/?id', functionN );

This definition allows you to define one optional parameter at the end of the path. It might be called using

'/store'

or using

'/store/108'

paths. Both HTTP calls will be directed to the same functionN service. In latter case, the '108' will be set as a parameter in the request object with the value of '108'.

General matcher

rest.get('/inquire/*book', functionM );

This definition gives you the possibility to define a general matcher allowing to have been called with anything after the string

'/inquire'

so can be called using

'/inquire/alice/in/wonderland'

or using

'/inquire/oz/the/great/wizard'

paths. This results to have the parameter 'book' with value

'alice/in/wonderland' or 'oz/the/great/wizard'

respectively.

You can make rather complex mixtures of those options as well:

'/borrow/:uid/?isbn/:bookTitle'

One can call this with uri:

'borrow/2/AliceInWonderland' or 'borrow/2/HG1232131/AliceInWonderland'

The character '*' can be used for both path and version too to make generic bindings:

{ path: '*', version: '*' }

Be aware, that this path will be matched to all paths within the defined context.

Special assigns:

You can use the all options above at once.

[ { path: '/rent/:country/?isbn/*bookTitle', version: '<2.0.0' }, { path: '/borrow/:uid/?isbn/?bookTitle', version: '>=2.1.1' } ]

Just define what you really need. :)

Parameter processing

The logic how connect-rest is managing parameter replacement is the following:

The parameters are processed in the path definition order and any missing optional parameter will be filled with empty strings to keep the order of them keeping in sight all mandatory parameters put after the optional ones.

Versioning

As for versioning, the syntax is semantic versioning, the same you use for npm

rest.get( { path: '/special', version: '1.0.0' }, functionN0);

So you can use different version specificaiton depending on your need:

version: '1.0.0 - 2.9999.9999'
version: '2.0.1'
version: '2.x'
version: '~1'
version: ">=1.0.2 <2.1.2"

Only the requests defining the right version number will match the defined paths.

connect-rest ignores all unmatching calls which might fail by the badly given path or version.

Back to Feature list

Rest functions

A rest function is a normal JS function you can define easily.

Every handler function receives

• a 'request' object containing "headers", "parameters", "files", "session" properties
• an optional 'content' object which is the object extracted from the http body's payload.
• an optional callback function. This is the 'node standard' way to manage callbacks if needed.

If callback is used as third parameter, needs to be called and pass the error or result object. Otherwise the return value of rest functions will be sent back to the client as a json string.

rest.get( { path: '/personal/:uid', version: '1.0.0' }, function( request, content, callback ){
	callback( null, { name: 'John Doe' } );
});
rest.get( '/purchases/:uid', function( request, content ){
	return { purchases: [ ... ] };
});

The async way is strongly encouraged to be used unless you have something really computation-free function...

Back to Feature list

Customize HTTP response

If one defines a rest function possessing 3 parameters, the third is the callback allowing 3 parameters to send. The first and second parameters are the conventional error and result objects.

The third one is an object aimed to contain to refine the HTTP response sent back to the client. This includes mime-types, status code, etc.

Status codes

As for status code, all you need to do is this:

Error case:

rest.get( '/invalidPath', function( request, content, callback ){
	var error = new Error('invalid path');
	error.statusCode = 404;
	return callback( error );
});

Special case when no error occurred, yet the http request's status has to be set:

rest.get( '/special', function( request, content, callback ){
	return callback( null, 'Processing...', { statusCode: 202 } );
});

Back to Feature list

Response headers

To refine the headers in the response HTML, the way is the same as above: customize the third parameter of the callback function.

rest.get( '/special', function( request, content, callback ){
	return callback( null, 'Content.', { headers: { ETag: "10c24bc-4ab-457e1c1f" } } );
});

Minify response JSON

You can make the response JSON object minified by passing a single boolean parameter to the callback's third optional parameter:

rest.get( '/special', function( request, content, callback ){
	...
	return callback( null, '{ "key"     :    "value" }', { minify: true } );
});

This will send

{"key":"value"}

to the client.

Customize answers of REST functions

When assigning routes with rest API you can pass an object too. This object looks like this:

{
	contentType: ''
	validator: ...
}

The contentType defines what the given REST service will retrieve. If not given, 'application/json' will be used.

The validator is a function, which can be used to determine if the REST function can be called in a given circumstances or should be ignored. This could mean authorization or ip address validation or other security concern.

rest.post( [ { path: '/shake', version: '>=2.0.0' }, { path: '/twist', version: '>=2.1.1' } ], function( request, content ){
	return JSON.stringify(content);
}, null, { contentType:'application/xml', validator: function(req, res){ return _.contains(req.user.roles, "superuser"); } } );

Back to Feature list

API_KEY management

The option passed to the connect-rest might contain an array enumerating accepted api_keys:

var options = {
	'apiKeys': [ '849b7648-14b8-4154-9ef2-8d1dc4c2b7e9' ]
	...
};

If property 'apiKeys' is present, the associated array of strings will be used as the list of api keys demanded regarding every incoming calls. So having such option, a call should look like this:

'/api/books/AliceInWonderland/1?api_key=849b7648-14b8-4154-9ef2-8d1dc4c2b7e9'

otherwise error response will be sent with status code 401 claiming: 'API_KEY is required.'.

Unprotected REST service

When you are using API_KEYs, you still might want to have 'exceptions'. Functions which can be served out of the border os API_KEY restriction. You can turn off that protection for a given service like this:

rest.get( { path: '/special', unprotected: true }, functionN0);

Protector

Protector is a function which can be passed when creating a rest services and decides if a given call is allowed or should be blocked and ignored. So the protector function called in every rest call when the given path is evaluated and matched and boolean return value of the function tells to the connect-rest to allow the rest function's execution to take place or blocked by some security reason.

rest.get( { path: '/special', protector: function(req, pathname, version){ return true; } }, functionN0);

The req object, the pathname and api call version is passed and the returning boolean version tells if call is allowed to be performed. You can have such functions to define session-based dynamic protection or differentiate between widely available rest calls and restricted business-sensitive feature.

Back to Feature list

Context

connect-rest uses context uri prefix by default to create a speparated 'namespace' for the rest functions. You can define it dynamically:

rest.context( '/api' ); // means that every rest calls need to be sent to '/api/X' path.

or through the option object as well when you add the middleware to the connect object:

var options = {
	'context': '/api'
};
connectApp.use( rest.rester( options ) );

Default context is the '/api' string.

Orchestrating the contexts

The connect-rest also allows you to specify the context at REST function level. This helps if you want to orchestrate your functions using multiple contexts. Let me show you:

rest.get( { path: '/workspace', context: '/pages' }, functionN0);

This REST function can be called by sending a GET request to the address of

/pages/workspace

This way you can easily manage dynamic templates not being forced to be in the same context as API calls.

You can orchestrate the contexts of your architecture as it pleases you.

Discovery services

connect-rest provides a built-in service: discover. Via a simple get request, it allows you - by specifying a version - to discover the plublished REST apis matching the given version.

var options = {
    'discoverPath': 'discover'
};
connectApp.use( rest.rester( options ) );

This will enable this service - considering the context described above - on the path '/api/discover/:version'. Sending a get request to - let's say - this path

http://localhost:8080/api/discover/3.0.0

would retrieve all services which can be called using version 3.0.0 (non-versioned and matching versioned services). The returned JSON is the following:

{
	"HEAD":["/peek"],
	"GET":["discover/:version","/books/:title/:chapter"],
	"POST":["/store",{"path":"/make","version":">=1.0.0"},"/act","/do",{"path":"/shake","version":">=2.0.0"},{"path":"/twist","version":">=2.1.1"}],
	"PUT":[],
	"DELETE":[]
}

Prototype services

The assign-methods allows you to pass a third parameter, an object which can be considered as a prototype of the expected parameter of the service when a client wants to make a call.

rest.post( [ { path: '/shake', version: '>=2.0.0' }, { path: '/twist', version: '>=2.1.1' } ], functionN, {'title': 'Alice in Wonderland'} );

That parameter debriefs the client what structure the functionN expects to receive. To activate this feature, first you have to add a new attribute to the options object:

var options = {
    'apiKeys': [ '849b7648-14b8-4154-9ef2-8d1dc4c2b7e9' ],
    'discoverPath': 'discover',
    'protoPath': 'proto',
    'logger': 'connect-rest'
};

This 'protoPath' means that sending a request to the server on path:

'/api/proto/POST/2.3.0/api/twist?api_key=849b7648-14b8-4154-9ef2-8d1dc4c2b7e9'

will retrieve the object

{'title': 'Alice in Wonderland'}

because the service

on path '/api/twist' and method 'POST' with version '2.3.0'

can be called and there is an assigned prototype object to it. Giving access method, version and path is mandatory for this feature.

Back to Feature list

Logging

In the option object passed to the constructor, there is an optional parameter 'logger', which enables the logging functionality:

var options = {
	'apiKeys': [ '849b7648-14b8-4154-9ef2-8d1dc4c2b7e9' ],
	'discoverPath': 'discover',
	'logger': 'connect-rest'
};

or

var options = {
    'apiKeys': [ '849b7648-14b8-4154-9ef2-8d1dc4c2b7e9' ],
    'discoverPath': 'discover',
    'logger': loggerInstance
};

You can set:

• a string, which will be interpret as the name of the logger seen in the logs, or
• passing a bunyan instance to be used.

In the absence of 'logger' property, no logs will be made. The connect-rest will use level 'info' for entry and exit points of services and 'debug' for the milestones of all internal processes.

Back to Feature list

Reflective publishing

connect-rest allows you to have an extremely easy and fast way to publish your services.

You can define your own services like this in a file (services.js in this example):

function health( request ){
	return 'ok';
};
function record( request, content ){
	return 'saved';
}
exports.health = health;
exports.record = record;

and publish them this way:

var services = require('./services');
...
rest.publish( services );

This will discover all functions assigned to the exports having a name which conforms the following regular expression:

/^[a-zA-Z]([a-zA-Z]|\d|_)*$/g

The logic is simple. If the function has

• 1 parameter: it will be a 'get' method
• 2 parameters: it will be a 'post' method

and the path will be its name. So, by executing one single statement you will automatically have the following services:

/health on Get
/record on Post

If you have 100 services defined, then 100 rest api you will have automatically. Nice.

Domain support

connect-rest adds support for domain-based error handling. To the options object you can pass a domain too:

var createDomain = require('domain').create;
...
var superDomain = createDomain();
...
var restDomain = createDomain();
superDomain.add( restDomain );
var options = {
	apiKeys: [ '849b7648-14b8-4154-9ef2-8d1dc4c2b7e9' ],
	discoverPath: 'discover',
	protoPath: 'proto',
	logger: 'connect-rest',
	domain: restDomain
};

By passing the restDomain object, connect-rest will assign req and rest object to that domain and in any occurring error, it will be sent to the caller with HTTP status code 500.

Back to Feature list

Answering async rest requests

connect-rest provides a way to serve async rest requests. It might be important - especially between fragmented server-side environment - to call rest services and accept the answer on a specific callback URL specified by the requestor.

The client has to specify a request parameter "callbackURL" possessing the callback URL where the answer has to be sent. Having sent the request, connect-rest will answer it right away with status code 200 and message Ok. and having the result created, it will sent via HTTP POST to the URL given in the HTTP parameters.

This process is performed behind the scenes, you do not have do anything special about it. If that parameter can be found in the HTTP request, the call will be threaten as async request.

Back to Feature list

Dispatchers

In some cases, you might face with a situation where other 3rd party connect library has to be used and the case might require for path-related logic to be used. connect-rest is designed to be able to use as simple path processing helper library as well.

connectApp.use( rest.dispatcher( 'GET', '/dispatcher/:subject', function(req, res, next){
	res.end( 'Dispatch call made:' + req.params['subject'] );
} ) );

This simple code makes is pretty straightforward. In case of a 'GET' HTTP request coming to the url '/dispatcher', the given function is executed. That function can be any third party connect lib you want to use.

Back to Feature list

Monitoring

connect-rest allows you to monitor and measure the execution of the published rest services. Every service execution measure the execution time and reports to a bus transparently. The commulated data is populated regularly as configured.

var options = {
	...,
	monitoring: {
		populateInterval: 6000,
		console: true,
		listener: function(data){ ... }
	}
};

By adding a monitoring to the options of the library, the monitoring can be activated. The population interval is defined via the populateInterval property measured in millisecs.

The property console - if present - will print the cumulated execution times grouped/structured by paths and version to the console.

The property listener - if present - allows you to pass a function which the populated data will be sent to. This way you can define own function to process the collected measurements.

More examples

I have collected a few examples from some implementations submited by users of connect-rest.

Might help to have a more complete picture about what you can reach and realize with this library. In case of any wanted scenario, please open a ticket and I will happily comply with it.

Example, how to restrict rest api calls to only those who logged in already, meaning to have some session info

var protectBySession = function(req, pathname, version){
	return req.session && req.session.uid;
};
rest.get( { path: '/model/person', unprotected: true, protector: protectBySession, version: '1.0.0' }, function( request, content, callback ){
	callback( null, personModel );
});

Example to how define a free-to-call rest function in a very restricted environment. Dynamic templating is a typical scenario, no versioning is needed, nore api_key or session-based protection, must be put on a separate context and result has mime-type of "text/html"

var allower = function(req, pathname, version){
	return true;
};
rest.get( { path: '/?page/?id', unprotected: true, protector: allower, context: '/pages' }, function( request, content, callback ){
	// render some page
	renderer.render( request.parameters.page, request.parameters.id, function(err, res){
		callback( err, res );
	} );
}, { contentType:'text/html' } );

A fairly complex REST path which is needed in some cases and a custom return status code:

rest.get( '/call/:system/?entity/?version/:subject/*', function( request, content, callback ){
	// Do some business logic
	return callback(null, 'Done.', {statusCode:201} );
}, { contentType:'application/json' } );

In this case you call this path by the following uris:

/call/library/books/AliceInWonderland
/call/library/books/2.0/AliceInWonderland
/call/library/AliceInWonderland
/call/library/AliceInWonderland/firstedition/chapter1

Not a typical or strictly REST-conform scenario, but you might end up with the need of complex URIs.

Tip: To manage all calls not handled by connect-rest could be also important. The following code demonstrates how to define a small middleware, which is executed when no REST function is matched.

app.use( rest.rester( options ) );
app.use( function(req, res, next){
	if(req.session)
		req.session.destroy();
	// render error page by some renderer...
	renderer.render( 'error', {}, function(err, html){
		res.writeHead( 500, { 'Content-Type' : 'text/html' } );
		res.end( html );
	} );
} );

License

(The MIT License)

Copyright (c) 2013 Imre Fazekas

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Bugs

See https://github.com/imrefazekas/connect-rest/issues.

Changelog

• 0.9.1: fixes...
• 0.9.0: context specification at REST function level is allowed.
• 0.8.x: fixes...
• 0.8.0: protector introduced
• 0.7.7: check function added. Now you can test if a given call would/allowed to take place.
• 0.7.x: fixes...
• 0.6.x: fixes...
• 0.6.0: dispatchers added
• 0.5.0: minifying services added
• 0.0.48: An rest service can now be unprotected
• 0.0.43-47: Various fixes/improvements
• 0.0.42: Incoming request count monitoring added
• 0.0.41: listener for populated measurements can be set
• 0.0.40: monitoring services (bus) added
• 0.0.3X: minor fixes, refined documentation
• 0.0.28.29: a case when mandatory parameter follows optional(s) has been fixed
• 0.0.26-27: async request fix
• 0.0.23-25: small fix for content type management
• 0.0.22: response header customization added
• 0.0.21:
  • async rest calling allowed by passing a http parameter: callbackURL
  • and some logging fixes
• 0.0.20: callback/next function passed to the services methods can receive third parameter: statusCode setting the http status of the response
• 0.0.19: assign function introduced for bulk http-method assignments for a given rest function
• 0.0.18: fixes
• 0.0.16:
  • better optional parameter handling allowing to use optional parameter chain like: /set/?department/?room
  • rewritten assing services. instead of passing a single validator, one has to pass on optional object: { contentType: '', validator: ...} which allows one to define validator and answer return content mime-type as well.
• 0.0.15 : Great changes from Joel Grenon, thank you! Standard callbacks introduced, better optional parameter handling and respecting error status code if exists
• 0.0.14 : Adding grunt project files
• 0.0.13 : Validator function can be also passed
• 0.0.12 : Domain (introduced in Node 0.8.0) support added
• 0.0.11 : First request parameter now has a callback for async rest calls
• 0.0.10 : Prototyping added
• 0.0.9 : General path matcher added, optional now marked with '?'
• 0.0.8 : Other body parsing middlewares are respected
• 0.0.6 : logging added
• 0.0.5 : optional parameter added
• 0.0.4 : API_KEY management added
• 0.0.3 : discovery managemenet added
• 0.0.2 : named parameters added
• 0.0.1 : initial release