phantom-api

phantom-api

phantom-api is a flexible, simple, and powerful web framework that disappears to allow you to focus on the application, not the framework.

Refer to sample_app/app.js for additional insights and explanations of how one might approach phantom-api for web service application development.

install and run

• $ npm install phantom-api

• $ cd node_modules/phantom-api/sample_app/

• $ node app.js

phantom-api should now be running. Open another terminal and test the API using the following curl examples.

example api requests

The following simple request calls an API public interface (curl's -i switch displays HTTP response header along with the body):

$ curl -i "http://localhost:5023/api/getBrotherOfThor/?greeting=Hi"

Try calling a private method:

$ curl -i "http://localhost:5023/api/_initialize/"

If a method expressed in the URL does not exist in your application or it exists but its name begins with "_" (private method), it is not accessible via the API.

The following example demonstrates the powerful, flexible, and simple phantom-api.

This sample API request includes:

• api version
• custom header
• id in the HTTP path
• x parameter in POST data
• y parameter in query string

In order to easily see what data the server application has access to, the JSON response includes the "params" object, which was received as the first parameter to the server method. Again, please view sample_app/app.js for application details.

$ curl -d "x=1" -H "X-Approved-By: Hit Girl" \
    "http://localhost:5023/api/v2.0/postFatherOfThor/46/?y=2"

the params object

The params object is passed as the first argument to each API method. By default the params object includes the following keys:

params._method - "GET", "POST", etc.
params._headers - HTTP request headers
params._custom_headers - X headers, a subset of _headers; provided as a convenience

If JSON is sent by the client, the following key contains the JSON payload:

params._json

sending JSON payload requests

If the client makes a request which sends a JSON string as its payload to an API method, phantom-api provides access to the parsed JSON object via params._json. Example curl request:

$ curl -X POST -H "Content-Type: application/json" -d \
    '{"cities":["Seoul","Shanghai","Taipei"]}' \
    http://localhost:5023/api/postFatherOfThor/46

And then the method gets the array of cities thusly:

this.postFatherOfThor = function( params, callback ) {
    var cities = params._json["cities"];
}

If the JSON string is malformed and fails to parse, then the error is available to the method via params._error.

create your own web services

Below is an example of how you could create app.js:

var phantom = require("phantom-api");

// Both User and Image functions could be in the same file or separate
// files, in which case they'd both could be required in app.js.
var User = function() {

    // Merely by defining a function pointer using the following syntax,
    // "getuser" becomes a public API
    this.getuser = function( params, callback ) {

        // Find the user record from db by id. Because "_retrieveById"
        // begins with an underscore, it is a private method, not exposed
        // to the public API.
        this._retrieveById( params.id, function(result) {

            // The 2nd parameter to the getuser method is "callback". It
            // sends back the result in an HTTP response to the client.
            callback( result );
        })
    };

    this.adduser = function( params, callback ) {
        this._addUser( params, function(add_status) {

            // If callback argument is an object, then phantom
            // automatically sends JSON back to client with appropriate
            // Content-Type in the response.
            callback( {status: add_status} );
        });
    }

}; // end of User function pointer

// Again, this Image module could be defined in another file and required.
var Image = function() {
    this.getimage = function( params, callback ) {

        // Instead of using the callback method, you can immediately
        // send back a response using the JavaScript return keyword.
        //
        // Since value being sent in the response is not an object,
        // the HTTP response will be plain text with applicable
        // Content-Type set in the HTTP response. phantom just does
        // what's right. (Don't worry, phantom allows you to override
        // its default behavior if need be.)
        return "this is plain text";
    }

}; // end of Image function pointer

// Okay, we've defined our application, represented by the User
// and Image functions. Let's start up phantom-api to make the
// APIs available.
//
// First set basic custom configuration, then start up the server.
phantom.setCustomConfig( {DOC_ROOT: "/var/www/my_app/public",
                          PORT: 7723} );

// Pass in classes as a variable number of arguments:
phantom.run( User, Image );

That's it. Now start up your app: $ node app.js

As mentioned previously, please examine sample_app/app.js for more ideas.

custom features

• phantom.setCustomConfig()
• phantom.setHttpStatusCode()
• phantom.setHttpResponseHeader()

Instead of using a config.js for user-defined config values, an inline object can be set just before phantom.run() is called in your app, e.g.:

var phantom = require("phantom-api");

var MyApp = new function() {

}

var conf = {
    PORT: 80,
    DOC_ROOT: "/var/www/my_sick_and_amazing_app/public"
};

phantom.setCustomConfig( conf );

// If there's only a single function object in your app,
// list syntax is still allowed, but not required:
phantom.run( MyApp );

If setCustomConfig() method is called, then reading and processing config.js is ignored.

phantom-api automatically takes care of setting HTTP response headers, status codes, etc. so you, as a developer, don't have to worry about such things.

However, there may be cases when the logic of your application requires that you override phantom-api's behavior.

Before your application returns its response (via return or callback() method), you can manually override the default HTTP status code in the response. Example code snippet in your method:

if ( something unexpectedly bad happens ) {
    phantom.setHttpStatusCode(500);
}

callback( result );

Do you need to set some custom HTTP headers in a particular response?

It's intuitive and easy! Example code snippet in your method:

if ( we need to send HTML instead of JSON ) {
    phantom.setHttpResponseHeader( {"Content-Type": "text/html; charset=utf-8"} );
}

callback( htmlResult );

phantom-api will revert to its default HTTP header behavior for API methods that do not call this method.

If you set a custom response header with a key that already exists in phantom's default header, your custom key will override phantom's default setting.

Duplicate key evaluation is performed case insensitively; if your custom key name is "Content-type" and phantom's is spelled "Content-Type" then the duplicate key will be found and your custom setting will replace it, preserving the case of your custom key.

CORS support

By default, phantom's HTTP response does not include Access-Control-Allow-Origin header. However, if you want your server to accept CORS requests, just include the ACCESS_CONTROL_ALLOW_ORIGIN key in your phantom config, e.g.:

phantom.setCustomConfig( {DOC_ROOT: "/var/www/my_app/public",
                          ACCESS_CONTROL_ALLOW_ORIGIN: "*",
                          PORT: 80} );

Setting it here will automatically include the header in every response so you don't have to manually set a custom header in each API interface method.

HTTP request and response objects

phantom-api is designed to automatically handle the most common HTTP tasks so the developer can focus on the application. However, there are cases in which a method requires access to the request or response object for special operations.

Thus the params object passed into each API method has the following keys available:

params.__request
params.__response

cache mechanism

phantom-api uses a built-in key/value store for saving objects in memory (currently not registered as a module with npm). Inspired by the movie, the class's name is TotalRecall and is exposed by the phantom-api module.

From within your application, the following examples illustrate what is possible with TotalRecall():

var phantom = require("phantom-api");

var cache = new phantom.TotalRecall();

// Optionally set a TTL. The cache will be refreshed on a per key/request
// basis after user defined time has elapsed. Following example is set to
// 5 minutes.
//
// TTL is disabled by default.
cache.setTimeoutInSeconds( 300 );

// Add something to the cache.
cache.put( "myKey", stored_data );

// Check if key is in the cache and retrieve data.
if ( cache.keyExists("myKey") ) {
    var stored_data = cache.get( "myKey" );
}

// Retrieve data from cache with optional 2nd argument.
//
// if "ipAddress" exists in cache, returns value from cache.
//
// If "ipAddress" key does not exist, returns value of
// 2nd argument.
// 
// If "ipAddress" key does not exist and no 2nd argument
// is provided, returns null.
//
// This behavior was copied from Python's get() function.
var data = cache.get( "ipAddress", "127.0.0.1" );

// Remove key/value from cache.
cache.removeKey( "myKey" );

// Clear entire cache.
cache.clear();

// Retrieve list of keys.
var key_list = cache.keys();

Have fun!

Gerry Gold

March 2014