ngnguyen1/chatapp

Chat demo application using nodejs, socketio and redis

Chat app demo using Nodejs, socketIO and redis

Requirement

• Nodejs(You can download at https://nodejs.org/ )
• Redis

Install

• Clone the project git clone https://github.com/NgaNguyenDuy/chatapp.git
• Change to directory chatapp and install all dependencies (include main dependancies and dev dependencies) by type: npm install
• Start redis server
• Start chat server with command: DEBUG=chatapp:init node server.js and go to http://localhost:7777 in your browser and enjoy.

Config

You can change the port or redis connect URL in file config.json that located at config/config.json

Flow

All the processing logic are in two files: lib/socket.js for server side and public/js/main.js for client side.

I used to expressjs module for web framework. See more at Expressjs.

I also used to socket.io module for in interaction between client and server side. See more at socket.io

In server, you must install socket.io module and require it to your server side. In client side, you must require socket.io/socket.js. In this case, i have configured for socket.io and my server listen in same port. So you don't enter the absolute path when client require socket.io library.

The first, i start application and the server(include websocket) will listen in a port (in this case is 7777). When started, socket.io will listen a default event - connection. So all clients side when connect to server, their will auto emit event connection.

From now, the client and server side will communicate directly with each other through events. To emit a event, use .emit('event_name', 'data'), to listen a event, use .on('event_name', callback). To broadcast, use .broadcast.emit('event_name', 'data'). Broadcasting means sending a message to everyone else except for the socket that starts it.

Events in application:

• connection: Default event of socket.io, will be fired when any client connect.
• disconnect: Default event of socket.io, will be fired when any client disconnect.
• history:req: The event will load old messages newest from redis database.
• join: The event will do something: broadcasting to clients that a new user connected, get all user (except itself - that socket) list from redis database, save user to database.
• welcome: The event will be emit a string welcome to client that connected.
• sendMess: The event will listen the messages that user has sent, then emit to all clients (include itself). In this event, we also save message to database.

Working with database - Redis: Redis is an open source, BSD licensed, advanced key-value cache and store. See more at Redis.io

You must require redis module to manipulating with Redis database.

In this application, i only manipulate with database when a new user connected, user send new message. So here are some API:

• redisClient.sadd('users', user_name) will add a user_name to the key users. It will ignored if user_name has exist in this key.
• redisClient.lpush('messages', messages, callback) will add all messages to key messages.
• redisClient.ltrim('messages', start_point, end_point) will trim an existing list that it will contain only elements in range from start_point to end_point.
• redisClient.lrange('messages', start_offset, end_offset, callback) will get specified elements of key messages. The start_offset and end_offset are zero-based indexes, it means 0 being the first element of list (the head of list), 1 being the next element. The offsets can also be negative numbers indicating offsets starting at the end of list. For example, -1 is the last element of the list, -2 for penultimate and so on.
• redisClient.smembers('users', callback) will get all of key users.

Some screenshots

License

MIT