Service.js

Service.js is a library for managing abstractions over how your program interacts with the outside world.

A "service" is an interface to some global funcationality. Examples would be error reporting, data persistence, API abstraction, performance monitoring, audio playback abstraction, even DOM manipulation abstraction.

An "implementation" of a service is an object that implements the service's interface and registers itself with the services library. There may be multiple implementations of a service, the priority is determined by the order of registration.

An "instance" of a service is a particular implementation that's been instantiated, intialized, and (usually) started. Instances are what the application code actually uses and can be accessed by calling Services.ready.

An example should help clear this up.

Example Usage

In this example, we have two implementations of the "Socket" service, which the pubsub service uses to actually accomplish sending and receiving messages. The SocketService service uses websockets and registers itself first, thereby having a higher priority. However, if the client doesn't have WebSockets, the PollingService implementation of 'Socket' will be started instead.

// Web socket implmentation of 'Socket'
var WebSocketService = Object.create(Services.Service);
WebSocketService.isUsable = function() {
  return 'WebSocket' in window;
};
Services.register('Socket', WebSocketService);

// Polling implementation of 'Socket'
var PollingSocketService = Object.create(Services.Service);
Services.register('Socket', PollingSocketService);

// Implementation of pubsub (there's only 1 in the example)
var Pubsub = Object.create(Services.Service);
Pubsub.onStart = function() {
  return Services.ready('Socket');
}
Pubsub.publish = function() { /* publish stuff */ }
Pubsub.subscribe = function() { /* subscribe to stuff */ }
Services.register('Pubsub', Pubsub);

// Later, in application code

// This is usually called once after all services are registered and your app
// is ready to start. In `window.onload` for instance.
Services.start();

// Anywhere in your app where you need to use a service, you can get access
Services.ready('Pubsub').spread(function(pubsub) {
  // `pubsub` is an instance of the Pubsub service implementation
  pubsub.publish('up and running!');
});

There is complete API documentation available.

Using the library

In a browser

Just include build/service.min.js in a script tag. Then Services will be globally available.

If you use AMD

• Copy build/service.amd.js to the appropriate place in your application, rename it service.js.
• Then you can just require(['service'] function(Services) {} to your heart's content.

In Node.js

npm install service-js

Then in your app all you need to do is require it:

var Services = require('service-js');

Development

Running tests

make test

Building a release

make release

Files will end up in the build directory.