A real-time chat application.
- This is a code challenge proposed by K.Lab.
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The task is to create a chat-system backend in nodeJS.
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Upon data sent from a client to any of the backends, the data should be pushed to all other clients connected to that channel.
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Upon connection of a client to a channel, the backend should send the last 10 messages to that client.
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clients only get messages for their specified channel.
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all messages persist in redis for 24h.
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(not pretty sure of this one) the system is horizontally scalable
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Use the barebones client you can clone the from here: https://github.com/Klab-Berlin/backendTestClient
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Use redis (http://redis.io/documentation) as a database to store the messages for 24h.
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Use this base lib and wrapper for websockets:
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A message has channel, author, text, timestamp fields.
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I used a few node-libs : websocket, redis, finalhandler, serve-static
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Solving the data sync problem.
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The architecture I opted for is client-server architecture. And used redis to store the messages in a sorted set.
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The advantage of WebSocket is two way communication. When one user sends a message (client -> server) then server sends that message to all conected users (server -> client).
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For client -> server communication I used simple text (UTF8Data).
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For server -> client I distinguished between 2 different types of message: server sends messages history server sends messages to users in the same channel Therefore every message is a simple JavaScript object (JSON).
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I included a file Steps which details my choices and which difficulties I faced.
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Clone the repository
git clone https://github.com/Yosr-Ch/chat-taskcd TestServer -
Install node libs
npm install -
Run the script
node index.js //or nodemon index.js to automatically restart the server upon changes
- The basic function that is working is opening 2 browser windows (chromium Version 53.0.2785.143, firefox version 50.0) and chat.