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A CGI-like router for building HTTP APIs that serves JavaScript programs from a directory.

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Getting Started

Register is a walk down memory lane to the good old days of Perl's CGI module. It is a CGI emulator for people who want to just start hacking away at the web program, script by script, until it's done.

Register is great for writing web APIs. I built it to complement Stencil, which is an API-only template language; instead of MVC, you have templates over and API. Because of this, Register focuses on building an API, not on generating HTML.


Get Register with NPM.

install npm register

Make a directory in which to build your Register application.

$ mkdir ./app
$ vim ./app/greet.cgi.js

Then you want to create a Register program.

require('register')(module, function (params, response) {
  response.setHeader('Content-Type', 'text/plain');
  response.end(params.greeting + ', World!');

Now you can run your Register web application.

$ register ./app
Register listening on port 8386 pid 981.

Test it out from the command line.

$ curl http://localhost:8386/greet?greeting=Hello
TK What does curl say here? Or what switches do I use go get only the body?
Hello, World!

Minimal Register Script

A minimal Register script will set a content type and write a result.

require('register')(function (params, response) {
  response.setHeader('Content-Type', 'text/plain');
  response.end(JSON.stringify(params || {}) + '\n');

Running a Register Script at the Command Line

You can now run you script from the command line to debug it. You can run it directly or run it through a debugger.

$ node params.cgi.js 'name=register&number=1'
Content-Type: text/plain


Testing Register Scripts with Mock Requests

Testing your register scripts is simplified by a mock request wrapper. Here we create at test that is a simple Node.js program, but you can use the mock request wrapper in the test framework of your choice.

var deepEqual = require ('assert').deepEqual;
var request = require('register/request')(require);

request('./hello.cgi.js', { name: 'register', number: 1 }, function (headers, body) {
  deepEqual(headers['Content-Type'], 'text/plain', 'headers are copacetic');
  deepEqual(JSON.parse(body), { name: 'register', number: 1 }, 'body is copacetic');

Note how we pass our require to the request function builder. It allows the request function to find scripts relative to the location of the test.

Serving Up Your Register Scripts

TK: Run the register server.

Embedding Register in Your Web Application

Register works with Sencha Connect to add Register scripts to your web service. We can create a service using a directory and add it to a Sencha Connect app.

var service = require('register/service');
var connect = require('connect');

var app = connect()


Register uses the directory driven Reactor router to generate the routes for your web application. It follows some conventions that convert the path of a script in a directory tree to the url path in your application.

Let's use this example directory.


Routing File Suffix

Only the files ending with .cgi.js are considered for addition to the path by the service. The file basename is used for the file path so that params.cgi.js in the directory is requested by the url http://localhost/params.

Index Files

If the file base name is index as in index.cgi.js, then that is the script that is run when url matches the directory name. index.cgi.js is run for the root url http://localhost/.

Path Slurping Files

If the file base name ends with an underscore, the script will match a url path. The ./articles/edit_.cgi.js will match http://localhost/articles/edit. Additionally, it will also match any sub-paths, so it would also match

The path would be passed into script as a pathInfo property of the request object.

This is all inspired by the good old days of creating web sites by letting them sprawl out over a directory on your web server. If you want to change the URL paths of your program, simply rename your files and move them into a different directory. There's no need to update your routing DSL. What you see is what you get.

Writing Scripts

A Register script is a JavaScript program that wraps a JavaScript function. It is a simple construct that maps a URL to a single function through a directory tree. The function acts as a run-of-the-mill request handler function for a server created with the Node.js HTTP API. It inspects the request object and sends response through the responseobject .

With Register we create our request handlers in files that we can copy between applications — gasp! — like in the good old days script archives. We can reorganize the routing of our application by reorganizing our scripts. When we look at our scripts in a tree view of the directory, we're seeing

Respond to a Request

We respond to a request by writing a response using the response object. The request object contains details about the request, like the URL, query parameters, and request headers. The response object contains methods for writing a message the browser can see.

You know this already if you've done any web programming with Node.js, these are the request and response objects created by the Node.js HTTP server.

Getting a Parsed URL

The request object has a URL property, but it is just a string. To do anything meaningful with that URL, we need to parse it — we need to split it up into it's component parts.

Register will save us a step and give us a parsed url if we request it. We request a parsed url simply by adding the parameter url to our handler function.

Handling Parameters

With our parsed URL we can inspect parameters using the query property of the parsed url.

Handling Path Information

Errors and Redirects

To send errors we use the control object, or do we?

Must be sent before body is sent.

Sending Errors

Sending Redirects


Asynchronous Control Flow

With Cadence.


register = require('register')

request = require('register/request')(require)

Exports a single function used to build a request wrapper. Pass

request(path, query, callback(error, headers, body))

Invokes a GET request on the Register script at path. The script path is relative to the require of the calling script. (See the function builder above for details on how that is possible.)

The query is an object used to form the query part of a query string. The callback is the standard callback for a Register script with the following parameters;

Change Log

Changes for each release.

Version 0.0.0

Mon Mar 25 18:44:29 UTC 2013