bogart

Bogart

A blazing fast rapid application development web framework using JSGI for node.

Getting Started

Bogart can be installed via npm.

npm install bogart

Alternatively, clone the git repository.

git clone git://github.com/nrstott/bogart.git

Hello World in Bogart

Make a directory: mkdir hello-world

Create the following file:

app.js

var bogart = require('bogart');

var router = bogart.router();
router.get('/', function(req) { 
  return "hello world"; 
});

router.get('/:name', function(req) {
  return 'hello '+req.params.name;
});

var app = bogart.app();
app.use(bogart.batteries); // A batteries included JSGI stack including streaming request body parsing, session, flash, and much more.
app.use(router); // Our router

app.start();

Start your app: node app.js

Visit it in a web browser at http://localhost:8080. Visit the route that says hello to you by name at http://localhost:8080/bob

Changing the port

If you can't run on 8080, change the app.start call e.g. app.start(9090, '127.0.0.1')

Routing

Routing in Bogart is simple and intuitive. A route is an HTTP method paired with an URL matching pattern and a handler function.

var router = bogart.router();
router.get('/', function(req) {
  return bogart.html('Hello World');
});

Routes are tested for matches in the order in which they are defined.

Route Patterns

Route patterns are matched against URLs. They may include named parameters that will be accessible via the params object of the req object passed to the route handler.

var router = bogart.router();
router.get('/hello/:name', function(req) {
  var greeting = 'Hello '+req.params.name;
  return bogart.html(greeting);
});

Route patterns support wildcards. Wildcards will match anything whereas regular named parameters will not match beyond a path separator ("/").

var router = bogart.router();
router.get('/hello/*', function(req, name) {
    return bogart.html('Hello '+req.params.splat[0]);
});

No Route Found

When no route pattern matches the request, a next jsgi application to be called may be specified either with the Router#notFound method or via a parameter to the function returned by bogart:router. If both techniques are used, then the parameter overrides the app specified by the Router#notFound method.

Specified by calling the Router#notFound method

var myRouter = bogart.myRouter();
router.get('/', index);
myRouter.notFound(function (req) {
  return bogart.html('Not Found', { status: 404 });
});

Specified as a parameter to the router

var myRouter = bogart.router();
myRouter.get('/', index);

var app = bogart.app();
app.use(myRouter(function (req) {
  return {
    status: 404,
    body: [ 'Not Found' ]
  };
}))

Regex Routes

When a route pattern is not powerful enough, regular expressions may be used to specify which URLs are to be matched.

var router = bogart.router();
router.get(/\/posts?/, function(req) {
  // Matches 'post' or 'posts'
  return bogart.html('Regex Route');
});

Parameters are via regular expression groups in regular expression routes. The parameter values are put in an Array in req.params.splat of the req object passed to the route handler.

var router = bogart.router();
router.get(/hello-(.*)/, function(req) {
  var name = req.params.splat[0];
  return bogart.html('Hello '+name);
});

Custom HTTP Verbs

To handle HTTP Verbs other than get, post, put, and delete, the route method of Router can be invoked.

var router = bogart.router();
router.route('options', '/', function (req) {
  // Logic for handling the request goes here.
});

Bogart Application

bogart.app makes it easy to setup a middleware chain and start coding. Combined with bogart.batteries (See Below), you can setup a full-stack JSGI application in two lines of code.

var app = bogart.app();
app.use(bogart.batteries);

After adding bogart.batteries, you will normally want to add a Router. This is also done with app.use. To start the application, use the start method.

var app = bogart.app();
app.use(bogart.batteries);

var router = bogart.router();
// NOTE: Here you would normally add some routes.

app.use(router);
app.start();

Response Helpers

Bogart includes helpers for creating JSGI Responses. The helpers, by convention, take a final parameter of an options object that allows the caller to override defaults. The options object is merged with the default JSGI Response values of the helper before the JSGI Response is returned.

Respond with JSON

Helper to create an HTTP 200 Success response with a Content-Type of application/json.

Sample Route:

var router = bogart.router();
router.get('/', function(req) {
  return bogart.json({ framework: 'Bogart' });
});

This route yields the following JSGI Response:

{
  status: 200,
  headers: { 'Content-Type': 'application/json' },
  body: [ '{ "framework": "Bogart" }' ]
}

Respond with CORS headers

Helper to send a JSON response with 'Access-Control-Allow-Origin', 'Access-Control-Allow-Methods', and 'Access-Control-Allow-Headers' headers to faciliate Cross-Origin Resource Sharing (CORS).

Sample Route:

var router = bogart.router();
router.get('/', function(req) {
  return bogart.cors({ framework: 'Bogart' });
});

This route yields the following JSGI Response:

{
  status: 200,
  headers: { 
    'Content-Type': 'application/json',
    'Access-Control-Allow-Origin': '*',
    'Access-Control-Allow-Methods': 'GET,PUT,POST,DELETE',
    'Access-Control-Allow-Headers': 'x-requested-with,*'
  },
  body: [ '{ "framework": "Bogart" }' ]
}

Redirect

Helper to create an HTTP 302 Temporary Redirect response.

Sample Route:

var router = bogart.router();
router.get('/', function(req) {
  return bogart.redirect('/some/other/url');
});

This route yields the following JSGI Response:

{
  status: 302,
  headers: { 'Location': '/some/other/url' },
  body: []
}

Error

Helper to create an HTTP 500 Internal Server Error response.

Sample Route:

var router = bogart.router();
router.get('/', function(req) {
  return bogart.error('<html>...</html>');
});

This route yields the following JSGI Response:

{
  status: 500,
  headers: { 'Content-Type': 'text/html' },
  body: [ '<html>...</html>' ]
}

Not Modified

Helper to create an HTTP 304 Not Modified response.

Sample Route:

var router = bogart.router();
router.get('/', function(req) {
  return bogart.notModified();
});

This route yields the following JSGI Response:

{
  status: 304,
  headers: {},
  body: []
}

File (Streaming!)

Helper to create an HTTP 200 Success response with a body streamed from the contents of a file. The Content-Type of the response is determined by the mime type of the file.

Sample Route:

var path = require('path');

var router = bogart.router();
router.get('/download/*', function(req) {
  var filePath = path.join(__dirname, 'public', req.params.splat[0]);

  return bogart.file(filePath);
});

This route yields the following JSGI Response:

{
  status: 200,
  headers: { 'Content-Type': '<mimetype of the file>' },
  body: fileStream // <-- A file stream
}

Proxy (Streaming!)

Helper to create a response that proxies the response from a URL.

Sample Route:

var router = bogart.router();
router.get('/google', function(req) {
  return bogart.proxy('http://www.google.com');
});

This route yields a JSGI Response that matches the response from the proxied URL.

Imperative Response Builder

Bogart includes the ResponseBuilder helper to provide an imperative interface. While not recommended as a goto style of programming in Bogart, there are times when buiding a response imperatively makes for cleaner, better code. This is true especially when working with callback based functions that cannot be wrapped by bogart.promisify.

var router = bogart.router();
router.get('/', function(req) {

  // Get a ResponseBuilder
  var res = bogart.res();

  doSomethingAsync(function(err, messageStr) {
    res.setHeader('Content-Type', 'text/plain');

    if (err) {
      res.status(500);
      res.send('Error');
      return res.end(); // We use return to break out of the function, do not want to continue executing after res.end()
    }

    res.status(200);
    res.send(messageStr);
    res.end(); // End the Response.  This is analagous to resolving a promise for a JSGI Response.
  });

  return res;
});

Using Session

The session middleware can be included individually with app.use(bogart.middleware.session) or by using batteries app.use(bogart.batteries) which includes a default stack of JSGI middleware.

A session function will be available on the request object passed to your route handlers. This function follows the jQuery style of arity determining if it is getting or setting a key/value pair. A call to session with one argument is a get to the value of the key referenced by the argument.

req.session('name'); // => value associated with 'name'

A call to session with two arguments is a set.

req.session('name', 'Nathan'); // sets the value of 'name' to 'Nathan'

Contrived Example

A set of two routes that use session:

router.get('/:name', function(req) {
  req.session('name', req.params.name);
  return bogart.redirect('/');
});

router.get('/', function(req) {
  return bogart.html('Hello ' +req.session('name'));
});

Visiting '/:name' ('/Nathan', '/Bob', etc...) will set a session key that will be displayed by the root route '/', after the redirect.

Running the Examples

In the 'examples' directory of the cloned source, there are several examples of bogart applications.

Hello World

The hello world example demonstrates a basic bogart applications. The application has a route, '/:name', that takes a name as a parameter in the request URL. The application responds with 'hello '. It also has a route, '/', that responds with hello world.

> cd examples
> node hello-world.js

Visit the application in your web browser at http://localhost:8080/Jim

Mustache Template with Layout

This example demonstrates usage of the mustache templating engine and a mustache layout. A layout is a page designed to hold other templates to avoid duplication of content.

> cd examples/mustache-layout
> node app.js

Visit the application in a web browser at http://localhost:8080/

Jade

If you would like to use Jade instead of Mustache, please npm install bogart-jade. Then in your application add require('bogart-jade') and the Jade ViewEngine will be available via bogart.viewEngine('jade'). See the github repository for more information.

Middleware

Bogart comes with a variety of JSGI middleware appliances. The batteries appliance includes a recommended JSGI application chain for normal usage.

Batteries

Frameworks are better when they come batteries included. Bogart ships with the batteries, it's just up to you to put them in if you want to use them.

The batteries middleware creates the following JSGI chain where nextApp is the JSGI appliance passed as the first parameter to batteries:

error -> validateResponse -> directory -> parted -> methodOverride
      -> session -> flash -> bodyAdapter -> stringReturnAdapter -> nextApp

Serve Static Files

The static example demonstrates using bogarts Directory middleware to serve an image.

> cd examples/static-server
> node app.js

Visit the application in a web browser at http://localhost:8080/. You should see the image.

Error

Translates rejected promises to a JSGI error response.

Flash

Provides Ruby-esque 'flash' variables, good only for the next request cycle. Flash session tracking and flash data is stored via encrypted cookies by default. These providers can be overriden with the Flash middleware options. An example flash data provider implementation with a Redis backend is available here: https://github.com/jdc0589/bogart-flash-redis

MethodOverride

Checks for the _method parameter or X-HTTP-METHOD-OVERRIDE header to override the HTTP method.

ParseJson

Parses the body of any request with an "application/json" content-type. The value of request body is reassigned with the parsed value. Use the Parted middleware instead unless you have a specific reason not to as it contains a superset of this functionality and also performs streaming parsing.

ParseForm

Parses the body of any request with an "application/x-www-form-urlencoded" content-type. The value of request body is reassigned with the parsed value. Use the Parted middleware instead unless you have a specific reason not to as it contains a superset of this functionality and also performs streaming parsing.

Parted

A JSGI wrapper around the excellent Parted middleware for Connect. Parted is a streaming multipart, json, and urlencoded parser.

Session

Standard flash middleware for bogart. Session id and data are stored in encrypted cookies by default, however this can be overridden with custom storage providers. A redis backed session data store is available here: https://github.com/jdc0589/bogart-session-redis

Design Philosophy

• Public APIs should be terse. Prefer bogart.app() to new bogart.Application().
• Be verbose when it does not increase typing for the API user. A good example of this would be in naming of function parameters. The parameter name does not affect the user of the API, so making it more verbose makes for better self-documenting code.
• Use promises when the contract fits. Never use an EventEmitter that should only be attached to in a specific scope and will only call a success and/or error callback one time.
• Use EventEmitter for signals that can fire any number of times.
• Prefer composition to inheritance.
• Avoid manipulating prototypes of Node.JS constructors. Manipulating prototypes makes for harder to understand code. Also, Bogart is expected to be cross-platform in the future.

Promises

Promises provide a well-defined interface for interacting with an object that represents the result of an action that is performed asynchronously. Why does Bogart use Promises instead of Callbacks for an interface? Because it's prettier and easier to reason about!

In all seriousness, I don't want to get into large arguments about the merits of Promises. Node.JS uses callbacks for its API; however, user-land applications and frameworks are free to employ higher-level abstractions and Bogart uses Promises.

Terminology

• Listener: A function listening for the resolution or rejection of a Promise.
• Resolve: A successful Promise is 'resolved' which invokes the success listeners that are waiting and remembers the value that was resolved for future success listeners that are attached.
• Reject: When an error condition is encountered, a Promise is 'rejected' which invokes the error listeners that are waiting and remembers the value that was rejected for future error listeners that are attached.
• Callback: A function executed upon successful resolution of a Promise.
• Errback: A function executed when a Promise is rejected
• Progressback: A function executed to provide intermediate results of a Promise.

How Promises Work

Promises may only be resolved one time. In the future, when success listeners are added to a promise that has already been resolved, the success listener will be invoked with the previously resolved value. Each success listener or error listener is invoked one time and one time only.

Promises are not EventEmitters. Many times when describing promises, other coders ask why not just use an EventEmitter. Promises have a different contract. The fact that promises are resolved or rejected only one time is powerful. EventEmitters have their place; however, they do not take the place of Promises and Promises do not take the place of EventEmitters.

function helloWorld() {
  // Retrieve the q promise utility
  var q = require('bogart').q;

  // Create a deferred, a wrapper around a Promise.
  var deferred = q.defer();

  // Do something async
  setTimeout(function() {
    // Resolve the promise, this will cause success listeners to be invoked.
    deferred.resolve('hello world');
  }, 100);

  // Return the promise that the deferred wraps to the client.
  return deferred.promise;
}

// Consuming the helloWorld function
var p = helloWorld();
p.then(function(msg) {
  // This function will be invoked on success
  console.log(msg);
}, function(err) {
  // This function will be invoked on error.
  console.log(err);
});

The then Method

promise.then(callback, errback, progress)

A promise will have a then method which takes up to three parameters. The three parameters are all optional. The first parameter, callback, is executed if the Promise is successfully resolved. The second parameter, errback, is executed if the Promise is rejected. The third parameter, progress, is used to provide intermediate feedback on the asynchronous operation. This parameter is rarely used. Most promises do not report progress.

The when Function

bogart.q.when(promiseOrValue, callback, errback, progress)

The when function in the bogart.q namespace is helpful when you do not know if what you have is a value or a promise for a value. The callback will be executed for success for a resoled promise or for the value passed if it is a value and not a promise.

// The following two lines are equivalent with the exception that the `when` can 
// handle values that are not promises.
q.when(p, function() { console.log('Success'); });
p.then(function() { console.log('Success'); });

Bubbling

Promises can be 'bubbled'. The return value of a callback becomes the value of an external promise. The same is true of errbacks.

function bubble(p) {
  return p.then(function() {
    // Assume makePromise is a function that returns a promise for an asyncronous operation.
    // The value of makePromise when resolved becomes the resolution of the `bubble` function as well.
    return makePromise();
  });
}

Bubbling errbacks is parallel to having a try/catch at a higher level handle errors at a lower level.

p.then(function(url) {
  return request(url).then(function() {
    throw 'error';
  });
}, function(err) {
  // Will handle the error that occurs in the callback of `request.then`.
  console.log(err);
});

Working with Node.JS Callbacks

Node.JS uses a style of callback with the following signuare: function(err, result). Bogart includes a utility function, bogart.promisify, to adapt these Node.JS-style functions to return a Promise.

var fs = require('fs'); // Node File System Module
var bogart = require('bogart'); // Include Bogart

// A promise-based version of fs.readFile.
var readFile = bogart.promisify(fs.readFile);

readFile('test.txt').then(function(data) {
  console.log(data);
});

NOTE: A Node.JS-style function which calls its callback multiple times is not compatible with promises. A Promise may be resolved only once. Node.JS style functions that call their callback multiple times are uncommon. The vast majority of Node.JS style functions can be safely translated using bogart.promisify.

Promises are 'A Good Thing'

There are a lot of critiques of Promises. These usually come from programmers who have not used a proper Promise library. Turst me, promises are 'A Good Thing'. Your code will be more composable, readable, and maintainable if you choose to use Promises instead of Callbacks for your API. It is also quite easy to transalate Node.JS style callbacks into promises using bogart.promisify so working wtih callback based APIs is still simple.

JSGI

JSGI stands for JavaScript Gateway Interface. It is an interface between web applications and web servers. It is similar to Ruby's Rack and Python's WSGI.

Entities

• Application: A JavaScript Function that takes one argument, the Request as a JavaScript Object, and returns its Response as a JavaScript Object containing three required attributes: status, headers, and body.
• Middleware: JSGI Applications that can call other JSGI Applications. Middleware can be organized into a call chain to provide useful services or perform useful business logic.
• Request: A JavaScript Object that contains the state of the HTTP request. JSGI Applications and Middleware are free to modify the request object.

Bogart Relationship to JSGI

Bogart makes it easy to create JSGI Applications and Middleware. Bogart is a high-level wrapper around JSGI.

Valid JSGI responses are always valid returns from Bogart. Bogart, via its helpful Middleware, also allows you to return Node.JS Streams, Node.JS Buffers, and JavaScript Strings as responses that will be translated into valid JSGI responses.

Bogart also provides helper functions to make creating JSGI responses easier. Prime examples of this are bogart.file which returns a JSGI response that serves a file and bogart.proxy which returns a response that proxies another URL.

Supporting Modules

• Jade View Engine: npm install bogart-jade

Contributors

• Nathan Stott
• Nick Fitzgerald
• Martin Murphy
• Davis Clark
• Aaron Shafovaloff
• Lewis Patterson
• William Skinner
• Duncan Smith
• Madison Sharps

License

Copyright (c) 2009 Nathan Stott <nathan.whiteboard-it.com>

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 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.