A simple Somata service with Node.js

A Somata service exposes methods that can be called by a Somata client elsewhere in your code. Let's make a simple SpeakerService that exposes two methods to say hello and goodbye.

CoffeeScriptJavaScript
somata = require 'somata'

# Create a new Somata service named 'hello' with a single method 'sayHello'

service = new somata.Service 'hello', {

    sayHello: (name, cb) ->
        cb null, 'Hello, ' + name + '!'

}
var somata = require('somata');

var service = new somata.Service('hello', {
    sayHello: function(name, cb) {
        return cb(null, 'Hello ' + name + '!');
    }
});
somata = require 'somata'

client = new somata.Client
client.remote 'hello', 'sayHello', 'Fred', (err, response) ->
    console.log 'Response: ' + response
var somata = require('somata');

var client = new somata.Client;

client.remote('hello', 'sayHello', 'Fred', function(err, response) {
  return console.log('Response: ' + response);
});
somata = require 'somata'

# Create a new Somata service named 'speaker'
service = new somata.Service 'speaker', {

    # With a few methods
    sayHello: (name, cb) ->
        cb null, 'Hello, ' + name + '!'

    sayGoodbye: (name, cb) ->
        cb null, 'Goodbye, ' + name + '!'
}
var service, somata;

somata = require('somata');

service = new somata.Service('speaker', {
  sayHello: function(name, cb) {
    return cb(null, 'Hello, ' + name + '!');
  },
  sayGoodbye: function(name, cb) {
    return cb(null, 'Goodbye, ' + name + '!');
  }
});

Now let's call these functions in order from another piece of code.

somata = require 'somata'

# Create a new Somata client
client = new somata.Client

# Execute SpeakerService.sayHello('world') and get the result...
client.remote 'speaker', 'sayHello', 'world', (err, hello) ->
    console.log '[speaker.sayHello] response: ' + hello

    # ... then execute SpeakerService.sayGoodbye('world')
    client.remote 'speaker', 'sayGoodbye', 'world', (err, goodbye) ->
        console.log '[speaker.sayGoodbye] response: ' + goodbye

        process.exit()
var client, somata;

somata = require('somata');

client = new somata.Client;

client.remote('speaker', 'sayHello', 'world', function(err, hello) {
  console.log('[speaker.sayHello] response: ' + hello);
  return client.remote('speaker', 'sayGoodbye', 'world', function(err, goodbye) {
    console.log('[speaker.sayGoodbye] response: ' + goodbye);
    return process.exit();
  });
});

Start the service, then run the client:

$ coffee speaker-service.coffee &
Somata service listening on localhost:15555...

$ coffee speaker-client.coffee
Found service speaker@localhost:15555
[speaker.sayHello] response: Hello, world!
[speaker.sayGoodbye] response: Goodbye, world!
$ node speaker-service.js &
Somata service listening on localhost:15555...

$ node speaker-client.js
Found service speaker@localhost:15555
[speaker.sayHello] response: Hello, world!
[speaker.sayGoodbye] response: Goodbye, world!

Subscribe to a remote event

Each Somata service can also publish events. Any client in the 'cluster/system' can then subscribe to these events as you would with any javascript event. Let's create a Service that will publish an 'announcement' with a message every second and print out the message elsewhere by subscribing to the 'announcement' event.

somata = require 'somata'

# Create a service with no methods
service = new somata.Service 'publisher', {}

# Publish an 'announcement' event with message 'Hey there, world!'
sendAnnouncement = ->
    service.publish 'announcement', 'Hey there, world!'

# Publish every second
setInterval sendAnnouncement, 1000
var sendAnnouncement, service, somata;

somata = require('somata');

service = new somata.Service('publisher', {});

sendAnnouncement = function() {
  return service.publish('announcement', 'Hey there, world!');
};

setInterval(sendAnnouncement, 1000);

Create a Client that subscribes to the 'announcement' event and logs the message

somata = require 'somata'

client = new somata.Client

# Subscribe to an 'announcement' event from the 'publisher' service
client.on 'publisher', 'announcement', (message) ->
    console.log '[subscriber.onAnnouncement] New message:', message
var client, somata;

somata = require('somata');

client = new somata.Client;

client.on('publisher', 'announcement', function(message) {
  return console.log('[subscriber.onAnnouncement] New message:', message);
});

Start the service and client

$ coffee publisher-service.coffee &
[didBind] Socket mulj67id bound to tcp://0.0.0.0:36206...
Registered service `publisher~ho5xqalh` on tcp://0.0.0.0:36206

$ coffee subscriber-client.coffee
[Client.subscribe] publisher~u3sg0zoj : announcement

Subscribing <mic9pdgi::publisher:announcementy7wq>
[subscriber.onAnnouncement] New message: Hey there, world!
[subscriber.onAnnouncement] New message: Hey there, world!
[subscriber.onAnnouncement] New message: Hey there, world!
...
$ node publisher-service.js &
[didBind] Socket mulj67id bound to tcp://0.0.0.0:36206...
Registered service `publisher~ho5xqalh` on tcp://0.0.0.0:36206

$ node subscriber-client.js
[Client.subscribe] publisher~u3sg0zoj : announcement

Subscribing <mic9pdgi::publisher:announcementy7wq>
[subscriber.onAnnouncement] New message: Hey there, world!
[subscriber.onAnnouncement] New message: Hey there, world!
[subscriber.onAnnouncement] New message: Hey there, world!
...

You can even subscribe to Services' events from the browser with somata-socketio.

For more examples, see https://github.com/somata/somata-node/tree/master/examples