Server API

TI-151:

• Megherea Eugen
• Ivasisin Ivan
• Poseletchi Cristian
• Taranovici Vasilie
• Petrov Cristina

Prerequisites

• All clients should use socket.io for simplicity
• All requests should be sent in binary format
• ALl requests from server are in binary format
• Client should store unique id (localstorage for example)

0. Run server locally

node dist/main.js

1. Connect to the server

By default socket server runs on port 3000. If you run your server locally, you should initialize socket on client as:

var client = io('localhost:3000');

2. Request-response mechanism

A request-response mechanism using WebSockets is a mechanism where you send a piece of information to the server and listen for repsonse. When you send a request to the server, server responds with the same event name and appending ':res' string to it.

For instance:

    client.on('init:res', function (data) {
        // here data contains response from server
    });
    client.emit('init', ConvertToBinary({
        id: 'mega-random-id',
        name: 'your name appearing in chat'
    }));

Note: not all requests will return a value in response, see later on

3. Events

Client --> Server events:

Event name	Data	Response value
init	An object with: name {string} - username to appear in chat id {string} - unique random id.	null
getParticipants	null	An array of participants (including you). Each participant is an object with id and name fields.
message	An object containing: to {string} - to whom the message goes from {string} - your unique id. If you provide another id, other user will never know from whom the message was body {string} - the text message itself	null
roommessage	same as message event	null
createroom	{ name: {string} - room name, participants: {string[]} - an array of participants id }	null
getRooms	null	An array of Rooms in which you are a member of. Each element is an object containing id {string}: room id, name {string} - room name,

Server --> Client events:

Event name	Data
update	An object which may contain fields which were updated. For now, update is only for notifiing about participant list change. It will contain participants field, which is an array of participants (Exactly the same as in getParticipants event)
message	An object containing from and body fields.
inviteRoom	An object containing id {string}: room id, name {string} - room name,

General flow

1. When page loads, client will ask user to input his/her name.
2. App should generate/get id and send init request to the server.
3. Client should ask for participants list by sending getParticipants event and waiting for server to respond with an array of participants. Do not forget to filter yourself from that array.
4. After client got the array, he/she should render in in page, using provided name field.
5. At this point client should add event listener for update and message event comming from the server.

4. Binary <-/-> JSON

Use this code to serialize/deserialize messages. You should call toBinary before sending anything. You should call toJSON to parse the binary message. NOTE: There is no error handling whatsoever, be careful

function toBinary (data) {
  data = JSON.stringify(data);
  var string = btoa(unescape(encodeURIComponent(data))),
    charList = string.split(''),
    uintArray = [];
  for (var i = 0; i < charList.length; i++) {
    uintArray.push(charList[i].charCodeAt(0));
  }
  return new Uint8Array(uintArray);
}

function toJSON(uintArray) {
  uintArray = new Uint8Array(uintArray);
  var encodedString = String.fromCharCode.apply(null, uintArray);
  return JSON.parse(encodedString);
}

example:

    socket.emit('message', toBinary({
        to: 'id',
        from: 'another id',
        body: 'hello world'
    }));

    socket.on('message', (data) => {
        var msg = toJSON(data);
        // here msg is an json object
    });