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Connect is an extensible HTTP server framework for [node](http://nodejs.org) using "plugins" known as _middleware_. ```js var connect = require('connect'); var http = require('http'); var app = connect(); // gzip/deflate outgoing responses var compression = require('compression'); app.use(compression()); // store session state in browser cookie var cookieSession = require('cookie-session'); app.use(cookieSession({ keys: ['secret1', 'secret2'] })); // parse urlencoded request bodies into req.body var bodyParser = require('body-parser'); app.use(bodyParser.urlencoded({extended: false})); // respond to all requests app.use(function(req, res){ res.end('Hello from Connect!\n'); }); //create node.js http server and listen on port http.createServer(app).listen(3000); ``` ## Getting Started Connect is a simple framework to glue together various "middleware" to handle requests. ### Install Connect ```sh $ npm install connect ``` ### Create an app The main component is a Connect "app". This will store all the middleware added and is, itself, a function. ```js var app = connect(); ``` ### Use middleware The core of Connect is "using" middleware. Middleware are added as a "stack" where incoming requests will execute each middleware one-by-one until a middleware does not call `next()` within it. ```js app.use(function middleware1(req, res, next) { // middleware 1 next(); }); app.use(function middleware2(req, res, next) { // middleware 2 next(); }); ``` ### Mount middleware The `.use()` method also takes an optional path string that is matched against the beginning of the incoming request URL. This allows for basic routing. ```js app.use('/foo', function fooMiddleware(req, res, next) { // req.url starts with "/foo" next(); }); app.use('/bar', function barMiddleware(req, res, next) { // req.url starts with "/bar" next(); }); ``` ### Error middleware There are special cases of "error-handling" middleware. There are middleware where the function takes exactly 4 arguments. When a middleware passes an error to `next`, the app will proceed to look for the error middleware that was declared after that middleware and invoke it, skipping any error middleware above that middleware and any non-error middleware below. ```js // regular middleware app.use(function (req, res, next) { // i had an error next(new Error('boom!')); }); // error middleware for errors that occurred in middleware // declared before this app.use(function onerror(err, req, res, next) { // an error occurred! }); ``` ### Create a server from the app The last step is to actually use the Connect app in a server. The `.listen()` method is a convenience to start a HTTP server (and is identical to the `http.Server`'s `listen` method in the version of Node.js you are running). ```js var server = app.listen(port); ``` The app itself is really just a function with three arguments, so it can also be handed to `.createServer()` in Node.js. ```js var server = http.createServer(app); ``` ## Middleware These middleware and libraries are officially supported by the Connect/Express team: - [body-parser](https://www.npmjs.com/package/body-parser) - previous `bodyParser`, `json`, and `urlencoded`. You may also be interested in: - [body](https://www.npmjs.com/package/body) - [co-body](https://www.npmjs.com/package/co-body) - [raw-body](https://www.npmjs.com/package/raw-body) - [compression](https://www.npmjs.com/package/compression) - previously `compress` - [connect-timeout](https://www.npmjs.com/package/connect-timeout) - previously `timeout` - [cookie-parser](https://www.npmjs.com/package/cookie-parser) - previously `cookieParser` - [cookie-session](https://www.npmjs.com/package/cookie-session) - previously `cookieSession` - [csurf](https://www.npmjs.com/package/csurf) - previously `csrf` - [errorhandler](https://www.npmjs.com/package/errorhandler) - previously `error-handler` - [express-session](https://www.npmjs.com/package/express-session) - previously `session` - [method-override](https://www.npmjs.com/package/method-override) - previously `method-override` - [morgan](https://www.npmjs.com/package/morgan) - previously `logger` - [response-time](https://www.npmjs.com/package/response-time) - previously `response-time` - [serve-favicon](https://www.npmjs.com/package/serve-favicon) - previously `favicon` - [serve-index](https://www.npmjs.com/package/serve-index) - previously `directory` - [serve-static](https://www.npmjs.com/package/serve-static) - previously `static` - [vhost](https://www.npmjs.com/package/vhost) - previously `vhost` Most of these are exact ports of their Connect 2.x equivalents. The primary exception is `cookie-session`. Some middleware previously included with Connect are no longer supported by the Connect/Express team, are replaced by an alternative module, or should be superseded by a better module. Use one of these alternatives instead: - `cookieParser` - [cookies](https://www.npmjs.com/package/cookies) and [keygrip](https://www.npmjs.com/package/keygrip) - `limit` - [raw-body](https://www.npmjs.com/package/raw-body) - `multipart` - [connect-multiparty](https://www.npmjs.com/package/connect-multiparty) - [connect-busboy](https://www.npmjs.com/package/connect-busboy) - `query` - [qs](https://www.npmjs.com/package/qs) - `staticCache` - [st](https://www.npmjs.com/package/st) - [connect-static](https://www.npmjs.com/package/connect-static) Checkout [http-framework](https://github.com/Raynos/http-framework/wiki/Modules) for many other compatible middleware! ## API The Connect API is very minimalist, enough to create an app and add a chain of middleware. When the `connect` module is required, a function is returned that will construct a new app when called. ```js // require module var connect = require('connect') // create app var app = connect() ``` ### app(req, res[, next]) The `app` itself is a function. This is just an alias to `app.handle`. ### app.handle(req, res[, out]) Calling the function will run the middleware stack against the given Node.js http request (`req`) and response (`res`) objects. An optional function `out` can be provided that will be called if the request (or error) was not handled by the middleware stack. ### app.listen([...]) Start the app listening for requests. This method will internally create a Node.js HTTP server and call `.listen()` on it. This is an alias to the `server.listen()` method in the version of Node.js running, so consult the Node.js documentation for all the different variations. The most common signature is [`app.listen(port)`](https://nodejs.org/dist/latest-v6.x/docs/api/http.html#http_server_listen_port_hostname_backlog_callback). ### app.use(fn) Use a function on the app, where the function represents a middleware. The function will be invoked for every request in the order that `app.use` is called. The function is called with three arguments: ```js app.use(function (req, res, next) { // req is the Node.js http request object // res is the Node.js http response object // next is a function to call to invoke the next middleware }) ``` In addition to a plan function, the `fn` argument can also be a Node.js HTTP server instance or another Connect app instance. ### app.use(route, fn) Use a function on the app, where the function represents a middleware. The function will be invoked for every request in which the URL (`req.url` property) starts with the given `route` string in the order that `app.use` is called. The function is called with three arguments: ```js app.use('/foo', function (req, res, next) { // req is the Node.js http request object // res is the Node.js http response object // next is a function to call to invoke the next middleware }) ``` In addition to a plan function, the `fn` argument can also be a Node.js HTTP server instance or another Connect app instance. The `route` is always terminated at a path separator (`/`) or a dot (`.`) character. This means the given routes `/foo/` and `/foo` are the same and both will match requests with the URLs `/foo`, `/foo/`, `/foo/bar`, and `/foo.bar`, but not match a request with the URL `/foobar`. The `route` is matched in a case-insensitive manor. In order to make middleware easier to write to be agnostic of the `route`, when the `fn` is invoked, the `req.url` will be altered to remove the `route` part (and the original will be available as `req.originalUrl`). For example, if `fn` is used at the route `/foo`, the request for `/foo/bar` will invoke `fn` with `req.url === '/bar'` and `req.originalUrl === '/foo/bar'`. ## Running Tests ```bash npm install npm test ``` ## People The Connect project would not be the same without all the people involved. The original author of Connect is [TJ Holowaychuk](https://github.com/tj) The current lead maintainer is [Douglas Christopher Wilson](https://github.com/dougwilson) [List of all contributors](https://github.com/senchalabs/connect/graphs/contributors) ## Node Compatibility - Connect `< 1.x` - node `0.2` - Connect `1.x` - node `0.4` - Connect `< 2.8` - node `0.6` - Connect `>= 2.8 < 3` - node `0.8` - Connect `>= 3` - node `0.10`, `0.12`, `4.x`, `5.x`, `6.x`, `7.x`, `8.x`, `9.x`, `10.x`, `11.x`, `12.x`; io.js `1.x`, `2.x`, `3.x` ## License [MIT](LICENSE) [coveralls-image]: https://badgen.net/coveralls/c/github/senchalabs/connect/master [coveralls-url]: https://coveralls.io/r/senchalabs/connect?branch=master [npm-downloads-image]: https://badgen.net/npm/dm/connect [npm-url]: https://npmjs.org/package/connect [npm-version-image]: https://badgen.net/npm/v/connect [travis-image]: https://badgen.net/travis/senchalabs/connect/master [travis-url]: https://travis-ci.org/senchalabs/connect