title	description	author	created	modified
Chime	Real Time Channel Based Messaging for Smart TVs	Marc Leef	2015 November 15	2016 January 10

Chime

Chime: Real Time Channel Based Messaging for Smart TVs

Overview

Chime is a high-performance chat server designed specifically to be used in conjunction with Smart TV applications. Chime can be deployed as either a monolithic instance or as a group of worker instances reporting to a master as pictured below.

Project Structure

The Chime backend is written in Java and can be found in backend/src. The Chime frontend is written in Javascript/HTML/CSS and can be found in frontend. The doc folder contains a detailed Javadoc of the project. The packaged, runnable jar files can be found in backend/jars.

Backend Usage

Default Ports

1. Socket Connections (Monolith/Worker): 4444
2. Web Socket Connections (Monolith/Worker): 4445
3. HTTP Requests (Monolith/Worker): 4567
4. HTTP Requests (Master) 4500

Monolithic Chime Instances

Constrained by the maximum number of TCP connections the host is capable of maintaining, but still fully functional.

To instantiate a monolithic Chime instance do:

java -jar chime-monolith.jar

Chime Workers and Master

Uses HTTP messages to coordinate a set of load balanced workers that can be scaled with the number of users.

To instantiate a Chime Master instance do:

java -jar chime-master.jar [Optional port #]

To instantiate a Chime Worker instance do:

java -jar chime-worker.jar [Chime Master URL]

Frontend Usage

Chime instances can be communicated with using JSON messages written to socket/web socket streams or sent via HTTP requests. Clients open and maintain a singular socket connection which is then used to update the backend of channel changes and chime sending events.

Chime Monolith Communication

To connect to a monolithic Chime instance from a browser do:

socket = new WebSocket("ws://[Chime instance URL]")

Then send a registration message like so:

// Channel change event
var registration = {
    registrationMessage : {
        previousChannel : null,
        newChannel : {id : "1"},
        television : {id : "marcs-tv"}
        timeSent : "1000"
    }
};
// Send to server
socket.send(JSON.stringify(registration));

Chimes can be sent similarly:

// New Chime message from client
var chime = {
    chimeMessage : {
        channel : {id : "1"},
        television : {id : "marcs-tv"},
        message : "This is amazing!.",
        timeSent : "1000"
    }
};
// Send to server
socket.send(JSON.stringify(chime));

To listen for Chimes sent from other clients:

// Message event listener
socket.onmessage = function (message) {
    messageObj = JSON.parse(message.data);
    // Do other stuff with message
}

Chime Worker/Master Communication

To connect to a Chime Worker instance first send a HTTP POST request to the master to be assigned a worker:

[Chime Master URL]/worker/assignment

The response should be a success object that contains a worker URL to connect to (open socket with as above):

{
    success : "[Worker URL]"
}

The worker URL can then be communicated with in the same manner as the monolithic setup through a web socket connection.

System Design