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This is a fork of the original bluechatter: https://github.com/IBM-Bluemix/bluechatter The BlueChatter app is a very simple chat/IRC type app for your browser. It is very basic, you just go to the app, enter a user name and start chatting.

For a demonstration of this application you can watch the following YouTube video.

To get started, click Create toolchain.

BlueChatter uses Node.js and Express for the server. On the frontend BlueChatter uses Bootstrap and JQuery. The interesting part of this application is how the communication of messages is done. The application uses long polling to enable the clients (browsers) to listen for new messages. Once the app loads a client issues a request to the server. The server waits to respond to the request until it receives a message. If no message is received from any of the chat participants it responds back to the client with a 204 - no content. As soon as the client gets a response from the server, regardless of whether that response contains a message or not, the client will issue another request and the process continues.

One of the goals of this application is to demonstrate scaling in Bluemix. As we know when you scale an application in Bluemix you essentially are creating multiple instance of the same application which users will connect to at random. In other words there are multiple BlueChatter servers running at the same time. So how do we communicate chat messages between the servers? We use the pubsub feature of Redis to solve this. All servers bind to a single Redis instance and each server is listening for messages on the same channel. When one chat server receives a chat message it publishes an event to Redis containing the message. The other servers then get notifications of the new messages and notify their clients of the. This design allows BlueChatter to scale nicely to meet the demand of its users.