Node Hermes

A node library written in Typescript, used for communication between front- & backend. Communication between backend and Hermes is done over Redis and communication between frontend and Hermes is done using sockets.

Setup (Typescript)

To avoid duplicate typings included from other packages, the following typings packages must be installed to compile the project:

• bluebird (ambient)
• chai (ambient)
• form-data (ambient)
• mocha (ambient)
• node (ambient)
• redis (ambient)
• request (ambient)
• request-promise (ambient)
• socket.io (ambient)
• socket.io-client (ambient)
• lodash

To ensure the same version, please see typings.json.

Usage

Basic example of spawning a Hermes instance.

var httpConfig = {
  listenOnPort: 5000
};

var apiConfig = {
  baseUri: 'api.test.dev',
  apiToken: 'testToken'
};

var socketServerConfig = {
  events: []
};

var redisConfig = {
  initialSubscribes: ['test1', 'test2']
};

var hermes = new Hermes(httpConfig, apiConfig, socketServerConfig, redisConfig);

hermes.run();

Components

Hermes contains the following components:

Http server

A basic http server.

Configuration

The only configurable parameter for the http server is the listenOnPort parameter.

Redis connection

Two connections to a Redis instance; one subscriber and one publisher. See src/lib/redis/redis-connection.ts for details.

Usage

Example of subscribing, unsubscribing and publishing to Redis:

// Spawn a Hermes instance, see Usage section

var redisConnection:RedisConnection = hermes.redisConnection;

// Start listening for a Redis event
redisConnection.subscribe('test-channel');

// Stop listening on a Redis event
redisConnection.unsubscribe('test-channel');

// Send an event over Redis
redisConnection.publish('test-channel', {data: 'some interesting data'});

Example of handling incoming event over Redis:

// Spawn a Hermes instance, see Usage section

var redisConnection:RedisConnection = hermes.redisConnection;

redisConnection.subscribe('test-event');

// Handle incoming event
redisConnection.on('test-event', (data:any) => console.log(data);

Configuration

The redis connection is configurable when spawning Hermes. All parameters are optional.

• port the port used by your Redis server, default 6379
• host the host name used by your Redis server, default localhost
• initialSubscribes a list of Redis events to subscribe to after Redis connection has been established, default []
• connectionConfig config object passed to package redis when connection is created

Events

The following events are triggered by the Redis connection:

• redis:subscriber:connected triggered when subscriber channel is established
• redis:publisher:connected triggered when publisher channel is established
• redis:subscriber:subscribed triggered when the subscriber successfully subscribed to an event
• redis:subscriber:unsubscribed triggered when the subscriber successfully unsubscribed from an event
• redis:connection:error triggered when we receive a Redis error
• <event-name> triggered when there's an incoming event over Redis we are subscribed to

Socket server

A SocketIO server listening for incoming socket connections.

Authentication

Hermes authenticates every incoming connection by listening to a user:authenticate event being sent through the socket. The provided access token is then sent to a configurable api uri (see Configuration) to validate the access token.

Note: Hermes will only handle one user:authenticate event at a time from a specific socket.

Successful

If the user is authenticated, Hermes will respond with a user:authenticated event over the same socket with data {success: true} and also add the socket to the system. After successful authentication, all configured events (see Configuration) will be handled.

To unregister from the system. The socket must either disconnect or a user:logout event must be sent over the socket.

Failed

If authentication fails, Hermes will respond with a user:authenticated event over the same socket with data {success: false}. If max attempts are exceeded Hermes sends a socket:closed event and then disconnects the socket.

Usage

Basic usage of the Socket Server

// Spawn Hermes instance
var socketServer:SocketServer = hermes.socketServer;
socketServer.on('new:user', (connection:SocketConnection) => {
    connection.on('test-event', (data:any) => console.log(data));
});

// socket is an incoming connection to Hermes
socket.emit('user:authenticate', 'access-token');
// Hermes will now respond with {'success': true} and internally trigger the 'new:connection' event

socket.emit('test-event', {data: 'important stuff'});
// {data: 'important stuff'} is now written in the console

// Unregister from Hermes
socket.emit('user:logout');

Configuration

The socket server is configurable when spawning Hermes.

• events a list of events that the system should handle, default []
• maxAuthenticateAttempts number of times a socket is allowed to fail authentication before it is disconnected, default infinite

Events

Events triggered by the Socket server:

• new:user triggered when a new user connects to the system
• new:socket triggered when an existing user connects with another socket
• user:authenticated triggered when an authentication has been processed

User Api

A user api component used to authenticate a user against a given backend.

Configuration

The following parameters are available to be configured:

• baseUri the base uri of the api, mandatory.
• apiToken the token sent in the authorization header by Hermes to the backend
• authenticationUri uri used to authenticate and retrieve the user by Hermes, default /users/me

Tests

To run tests simply install dev-dependencies and run mocha.

Note: The socket server will spawn a http server on port 5000, make sure it is not in use.

License

Copyright (c) 2016 Interactive Solutions Bodama AB

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.