The moleculer-io is a Websocket gateway service for Moleculer using socket.io.

$ npm install moleculer-io

• Usage
  • Init server
  • Handle socket events
  • Handle multiple events
  • Aliases
    • Mapping policy
  • Custom handler
  • Handler hooks
  • Calling options
  • Middlewares
  • Authorization
  • Joining and leaving rooms
  • Broadcast
  • CORS
  • Using multiple instances
  • Logging settings
  • Full settings
  • License
  • Contact

Usage

Init server

Using with Node http server:

const server = require('http').Server(app)
const SocketIOService = require("moleculer-io")
const ioService = broker.createService({
  name: 'io',
  mixins: [SocketIOService]
})

ioService.initSocketIO(server)

// Once the initSocketIO() was called, you can access the io object from ioService.io
broker.start()
server.listen(3000)

Or let moleculer-io create a server for you:

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    port: 3000 //will call initSocketIO() on broker.start()
  }
})
broker.start()

Or maybe you want to use it with moleculer-web

const ApiService = require("moleculer-web");
const SocketIOService = require("moleculer-io")
broker.createService({
  name: 'gateway',
  mixins: [ApiService, SocketIOService], //Should after moleculer-web
  settings: {
    port: 3000
  }
})
broker.start()

In this case, moleculer-io will use the server created by moleculer-web .

Handle socket events

Server:

const IO = require('socket.io')
const {
  ServiceBroker
} = require('moleculer')
const SocketIOService = require('moleculer-io')

const broker = new ServiceBroker()

broker.createService({
  name: "math",
  actions: {
    add(ctx) {
      return Number(ctx.params.a) + Number(ctx.params.b);
    }
  }
})

const ioService = broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    port: 3000
  }
})

broker.start()

By default, moleculer-io handle the call event which will proxy to moleculer's broker.call

Examples:

• Call test.hello action without params: socket.emit('call','test.hello', callback)
• Call math.add action with params: socket.emit('call','math.add', {a:25, b:13}, callback)
• Get health info of node: socket.emit('call','$node.health', callback)
• List all actions: socket.emit('call', '$node.actions', callback)

Example client:

const io = require('socket.io-client')
const socket = io('http://localhost:3000')
socket.emit('call', 'math.add', { a: 123, b: 456},
function(err, res) {
  if (err) {
    console.error(err)
  } else {
    console.log('call success:', res)
  }
})

Handle multiple events

You can create multiple routes with different whitelist, calling options & authorization.

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    port: 3000,
    io: {
      namespaces: {
        '/': {
          events: {
            'call': {
              whitelist: [
                'math.add'
              ],
              callOptions: {}
            },
            'adminCall': {
              whitelist: [
                'users.*',
                '$node.*'
              ]
            }
          }
        }
      }
    }
  }
})

Aliases

You can use alias names instead of action names.

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    port: 3000,
    io: {
      namespaces: {
        '/': {
          events: {
            'call': {
              aliases: {
                'add': 'math.add'
              },
              whitelist: [
                'math.add'
              ],
              callOptions: {}
            }
          }
        }
      }
    }
  }
})

Then doing socket.emit('call','math.add', {a:25, b:13}, callback) on the client side will be equivalent to socket.emit('call','add', {a:25, b:13}, callback).

Mapping policy

The event has a mappingPolicy property to handle events without aliases.

Available options:

• all - enable to handle all actions with or without aliases (default)
• restrict - enable to handle only the actions with aliases

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    port: 3000,
    io: {
      namespaces: {
        '/': {
          events: {
            'call': {
              mappingPolicy: 'restrict',
              aliases: {
                'add': 'math.add'
              },
              callOptions: {}
            }
          }
        }
      }
    }
  }
})

Custom handler

You can make use of custom functions within the declaration of an event handler.

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    port: 3000,
    io: {
      namespaces: {
        '/': {
          events: {
            'call': {},
            'myCustomEventHandler': function(data, ack) { // write your handler function here.
              let socket = this
              socket.emit('hello', 'world')
              socket.$service.broker.call('math.add', {
                a: 123,
                b: 456
              })
            }
          }
        }
      }
    }
  }
})

There is an internal pointer in socket objects:

• socket.$service is pointed to this service instance.

Handler hooks

The event handler has before & after call hooks. You can use it to set ctx.meta, access socket object or modify the response data.

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    io: {
      namespaces: {
        '/': {
          events: {
            'call': {
              whitelist: [
                'math.*'
              ],
              onBeforeCall: async function(ctx, socket, action, params, callOptions) { //before hook
                  console.log('before hook:', params)
                },
              onAfterCall: async function(ctx, socket, res) { //after hook
                console.log('after hook', res)
                // res: The respose data.
              }
            }
          }
        }
      }
    }
  }
})

Calling options

The handler has a callOptions property which is passed to broker.call. So you can set timeout, retryCount or fallbackResponse options for routes.

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    io: {
      namespaces: {
        '/': {
          events: {
            'call': {
              callOptions: {
                timeout: 500,
                retryCount: 0,
                fallbackResponse(ctx, err) { ...
                }
              }
            }
          }
        }
      }
    }
  }
})

Note: If you provide a meta field here, it replaces the socketGetMeta method's result.

Middlewares

Register middlewares. Both namespace middlewares and packet middlewares are supported.

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    io: {
      namespaces: {
        '/': {
          middlewares: [ //Namespace level middlewares, equipment to namespace.use()
            function(socket, next) {
              if (socket.request.headers.cookie) return next();
              next(new Error('Authentication error'));
            }
          ],
          packetMiddlewares: [ // equipment to socket.use()
            function(packet, next) {
              if (packet.doge === true) return next();
              next(new Error('Not a doge error'));
            }
          ],
          events: {
            'call': {}
          }
        }
      }
    }
  }
})

Note: In middlewares the this is always pointed to the Service instance.

Authorization

You can implement authorization. Do 2 things to enable it.

• Set authorization: true in your namespace
• Define the socketAuthorize method in service.

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    io: {
      namespaces: {
        '/': {
          authorization: true, // First thing
          events: {
            'call': {
              whitelist: [
                'math.*',
                'accounts.*'
              ]
            }
          }
        }
      }
    }
  },
  methods: {
    // Second thing
    async socketAuthorize(socket, eventHandler){
      let accessToken = socket.handshake.query.token
      if (accessToken) {
        try{
          let user = await this.broker.call("user.verifyToken", {accessToken})
          return {id: user.id, email: user.email, token: accessToken}  // valid credential, return the user
        }catch(err){
          throw new UnAuthorizedError() // invalid credentials
        }
      } else {
        // anonymous user
        return
      }
    }
  }
})

Client:

const socket = io({
  query: {
    token: '12345'
  }
})

See examples/full

Also you could overwrite the socketGetMeta method to add more addition meta info. The default socketGetMeta method is:

socketGetMeta(socket){
  return {
    user: socket.client.user,
    $rooms: Object.keys(socket.rooms)
  }
}

Example to add more additional info:

broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  methods: {
    socketGetMeta(socket) { //construct the meta object.
      return {
        user: socket.client.user,
        $rooms: Object.keys(socket.rooms),
        socketId: socket.id
      }
    },
    // In addition, you can also customize the place where user is stored.
    // Here is the default method the save user:
    socketSaveMeta(socket, ctx) {
      socket.client.user = ctx.meta.user
    }
  }
})

If you want to authorize a user after socket connected, you can write an action to do it.

broker.createService({
  name: 'accounts',
  actions: {
    login(ctx){
      if(ctx.params.user == 'tiaod' && ctx.params.password == 'pass'){
        ctx.meta.user = {id:'tiaod'}
      }
    },
    getUserInfo(ctx){
      return ctx.meta.user
    }
  }
})

Joining and leaving rooms

In your action, set ctx.meta.$join or ctx.meta.$leave to the rooms you want to join or leave.

eg.

ctx.meta.$join = 'room1' //Join room1
ctx.meta.$join = ['room1', 'room2'] // Join room1 and room2

ctx.meta.$leave = 'room1' //Leave room1
ctx.meta.$leave = ['room1', 'room2'] // Leave room1 and room2

After the action is finished, moleculer-io will join or leave the room you specified.

Example room management service:

broker.createService({
  name: 'rooms',
  actions: {
    join(ctx){
      ctx.meta.$join = ctx.params.room
    },
    leave(ctx){
      ctx.meta.$leave = ctx.params.room
    },
    list(ctx){
      return ctx.meta.$rooms
    }
  }
})

Broadcast

If you want to broadcast event to socket.io from moleculer service:

broker.call('io.broadcast', {
  namespace:'/', //optional
  event:'hello',
  args: ['my', 'friends','!'], //optional
  volatile: true, //optional
  local: true, //optional
  rooms: ['room1', 'room2'] //optional
})

Note: You should change the 'io' to the service name you created.

CORS

moleculer-io will pick the settings.cors.origin option and use it to validate the request. (Which is also compatible with moleculer-web! )

broker.createService({
  name: 'io',
  mixins: [ApiGateway, SocketIOService],
  settings:{
		cors: {
			origin: ["http://example.com"], //Moleculer-io only pick up this option and set it to io.origins()
			methods: ["GET", "OPTIONS", "POST", "PUT", "DELETE"],
			allowedHeaders: [],
			exposedHeaders: [],
			credentials: false,
			maxAge: 3600
		}
	}
})

For detail see https://socket.io/docs/server-api/#server-origins-fn

Using multiple instances

If you plan for a highly available setup (launching multiple instances of this service behind a Load Balancer), you will have to take some extra steps. Due to the nature of WebSockets these instances will need a PubSub capable broker to connect to, in order to broadcast messages to sockets that are connected to other instances. For a more in depth explanation of this concept, and additional steps that have to be taken (such as Load Balancer configuration), refer to the Socket.io Documentation.

In order to interconnect this service with other services, start the service with an adapter:

const broker = new ServiceBroker({
    transporter: "redis://redis:6379"
})
broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    port: 3000,
    io: {
      options: {
        adapter: require("socket.io-redis")("redis://redis:6379")
      }
    }
  }
})

Logging settings

If you want to keep clean your project console or have a more deep way to debug the data sent over the socket you can just change some settings in your service to add/remove logs:

• logRequest: Log all the incoming request through the socket
• logRequestParams: Log the request params
• logResponse: Log response data
• logBroadcastRequest: Log the request to forward to the sockets
• logClientConnection: Log when a client gets connected

To start logging something indicate whatever logging level you want:

const broker = new ServiceBroker({
    transporter: "redis://redis:6379"
})
broker.createService({
  name: 'io',
  mixins: [SocketIOService],
  settings: {
    logClientConnection: 'info'
    port: 3000,
    io: {
      options: {
        adapter: require("socket.io-redis")("redis://redis:6379")
      }
    }
  }
})

logRequest, logRequestParams, logResponse are adopted from the API gateway, the other ones are managed only in this one and by default they are disabled

Full settings

settings: {
  port: 3000,
  io: {
    options: {}, //socket.io options
    namespaces: {
      '/':{
        authorization: false,
        middlewares: [],
        packetMiddlewares:[],
        events: {
          call: {
            mappingPolicy: 'all',
            aliases: {
              'add': 'math.add'
            },
            whitelist: [
              'math.*'
            ],
            callOptions:{},
            onBeforeCall: async function(ctx, socket, action, params, callOptions){
              ctx.meta.socketid = socket.id
            },
            onAfterCall:async function(ctx, socket, res){
             socket.emit('afterCall', res)
            }
          }
        }
      }
    }
  }
}

License

The project is available under the MIT license.

Contact

Copyright (c) 2021 MoleculerJS