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Loopback module for create Socket.io connections and allow call methods and make subscriptions

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loopback-socket

npm version Build Status Coverage Status

Loopback module for create Socket.io connections and allow call methods.

Installation

npm install loopback-socket --save

Usage

Server side

Include

const LoopbackSocket = require('loopback-socket');

LoopbackSocket.get(name, [timeout])

Create or get a instance with a specific name.

Arguments
Name Type Description
name string Name to instance. Required
[timeout] integer Time to wait authentication after establish connection before disconnect the socket. Optional.
Example
const loopbackSocket = LoopbackSocket.get('name');
const loopbackSocket = LoopbackSocket.get('name', 2000);

loopbackSocket.start(io)

Configure authentication, callbacks and methods with a server socket.

Arguments
Name Type Description
io object Server Socket IO instance. Required.
Example
const server = require('http').createServer();
const io = require('socket.io')(server);
loopbackSocket.start(io);

loopbackSocket.auth(authentication)

Set the function to authenticate connected sockets.

Arguments
Name Type Description
authentication autentication function or object Function called with (socket, credentials, [cb]) arguments or object like { model: Model, method: methodName } where Model is a class and methodName is one of its methods (defined or to be defined) like autentication function.
Authentication function

If an error is thrown in this function or it return a false value then authentication fails. If argument cb is not defined then the returned value will be a the authentication response, and if this value is a promise, then it will be resolved before.

Name Type Description
socket object Socket connected. Required.
credentials object Credentials received. Required.
[cb] function Callback with (err, success) arguments to async return value with NodeJs callback style. Optional.
Example
// Authentication function with NodeJs callback style
function customAuthentication(socket, credentials, cb) {
  User.getUserByCredentials(credentials, cb);
}

// Authentication function with direct value returned o Promise style
function customAuthentication(socket, credentials) {
  return User.getUserByCredentials(credentials); // return data or a promise
}

// Direct setting
loopbackSocket.auth(customAuthentication);

// Setting through a Model
function MyModel() {};

loopbackSocket.auth({
  model: MyModel,
  method: 'customAuthentication'
});

MyModel.customAuthentication = authentication;

loopbackSocket.onConnected(handler)

Add a on connected handler.

Arguments
Name Type Description
handler handler function or object Function called with (socket, credentials, [cb]) arguments or object like { model: Model, method: methodName } where Model is a class and methodName is one of its methods (defined or to be defined) with like handler function.
Handler function

If argument cb is not defined then the returned value will be a the handler response, and if this value is a promise, then it will be resolved before.

Name Type Description
socket object Socket connected. Required.
credentials object Credentials received. Required.
[cb] function Callback with (err, success) arguments to async return value with NodeJs callback style. Optional.
Example
// Authentication function with NodeJs callback style
function customOnConnectedHandler(socket, credentials, cb) {
  User.getUserByCredentials(credentials, cb);
}

// Authentication function with direct value returned o Promise style
function customOnConnectedHandler(socket, credentials) {
  return User.getUserByCredentials(credentials); // return data or a promise
}

// Direct adding
loopbackSocket.onConnected(customOnConnectedHandler);

// Adding through a Model
function MyModel() {};

loopbackSocket.onConnected({
  model: MyModel,
  method: 'customOnConnectedHandler'
});

MyModel.customOnConnectedHandler = customOnConnectedHandler;

loopbackSocket.removeOnConnected(handler)

Remove a connected handler

Arguments
Name Type Description
handler function or object Function called with (socket, credentials, [cb]) arguments or object like { model: Model, method: methodName } where Model is a class and methodName is one of its methods (defined or to be defined) with like handler function.
Example
// Direct remove
loopbackSocket.onConnected(customOnConnectedHandler);

// Remove Model method
function MyModel() {};

loopbackSocket.removeOnConnected({
  model: MyModel,
  method: 'customOnConnectedHandler'
});

loopbackSocket.defineMethod(methodName, method)

Define a method to call by socket connection or replace one existing.

Arguments
Name Type Description
methodName string Method name.
method method function or object Function called with (socket, credentials, args, [cb]) arguments or object like { model: Model, method: methodName } where Model is a class and methodName is one of its methods (defined or to be defined) with like method function.
Method function

If argument cb is not defined then the returned value will be the method called reponse, and if this value is a promise, then it will be resolved before.

Name Type Description
socket object Socket connected. Required.
credentials object Credentials received. Required.
args. object Arguments to call method. Required.
[cb] function Callback with (err, success) arguments to async return value with NodeJs callback style. Optional.
Example
/// Method function with NodeJs callback style
function customMethod(socket, credentials, args, cb) {
  let data;

  // Option 1
  cb(null, data); // Client receives { result: data }
  
  // Option 2
  cb('myError');  // Client receives { error: 'myError' }

}

/// Method function with direct value returned o Promise style
function customMethod(socket, credentials, args) {
  let dataOrPromise;

  // Option 1
  return dataOrPromise; // Client receives { result: dataOrPromiseResolvedValue }

  // Option 2
  throw 'myError'; // Client receives { error: 'myError' }

}

// Direct definition
loopbackSocket.defineMethod('customMethod', customMethod);


// Definition through a Model
function MyModel() {};

loopbackSocket.defineMethod('customMethod', {
  model: MyModel,
  method: 'customMethod',
});

MyModel.customMethod = customMethod;

loopbackSocket.removeMethod(methodName)

Remove a method of socket.

Arguments
Name Type Description
methodName string Method name to remove.
Example
// Direct remove
loopbackSocket.onConnected('customMethod');

Client side sample

const socket = io('http://localhost');

socket.on('connect', (socket) => {
  // send credentials
  socket.emit('authentication', credentials);
});

socket.on('authenticated', (socket) => {
  // socket authenticated
});

socket.on('unauthorized', (socket) => {
  // socket failed authentication
});

function callMyMethod() {
  // Call a defined socket method
  socket.emit('myMethod', {}, (response) => {
    if (response.error) {
      // Method return a error;
      return;
    }
    // Method success;
    console.log(response.result);
  });
}

Samples

Loopback + AngularJS:

https://github.com/arondn2/loopback-socket/tree/master/examples/loopback

Troubles

If you have any kind of trouble with it, just let me now by raising an issue on the GitHub issue tracker here:

https://github.com/arondn2/loopback-socket/issues

Also, you can report the orthographic errors in the READMEs files or comments. Sorry for that, I do not speak English.

Tests

npm test or npm run cover

Contributing

In lieu of a formal style guide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code.