itzcookiie / chat-app

chat-app

Objective: Build a chat room app using a socket server

Learning objectives:

• Learn and understand what a socket server is
• Learn how it relates to e.g. TCP, HTTP
• Create and start a socket server and send a request from a client
• Build a chat app using a socket server

---

Currently

• Create and start a socket server and send a request from a client ✅

Next steps

For the chat room effect

• Build 3 socket servers, one main and two child ones ✅

Part 1 ✅

• Send a message to the main socket from a client and broadcast/send that message to the other child ones

EDIT: I did this differently because the idea was for the main socket to connect the child socket to the clients. But doing it this way won't work because the child socket is not connected to the client. So basically, the client has to issue the connection for the child socket to send a response. Since only the main socket is connected it won't work.

Instead the client connects to the main socket, the main socket sends the address of the child socket (AKA room) and the client then connects to the child socket and sends messages there. The child socket will hold a list of users and send out messages to all the users there

Part 2 ✅

• Create two client sockets (or imagine you have 2 users)
  • Use input in a while loop to give the impression of a logged in user
• Map the two child server sockets to the two client sockets
• So when a client sends a message to the server, only it's chosen server socket will see the message (important part) and respond back to it
• IE. a client can identify itself with a particular server socket

Room isolation ✅

• Should be enough having each socket on a different port
• Unless e.g. you can only use one port per process/thread or something like that
• In a situation like that, we will do multiprocessing
• Each room will have it's own socket (that will be the seperation. So each room AKA socket will have it's own unique users subscribed to it. E.g. User A and B are in room 1 or port 5000)
• Each room run in it's own process

---

Learnings

• Learned that with socket servers, the server can send data/messages to the client at any time. With just HTTP, only the client can issue requests (or send data/messages).

How does a socket server work

• You first of all create a socket
• The socket will bind itself to a port (or address). Basically an ID, so it can be located
• The socket then listens() for requests. This makes the socket accessible/open for connection to other sockets
• The socket then accepts() requests. Accept basically means it starts processing the requests made to it

What is a socket server

• A socket server is a way of transferring data between machines over a network

How HTTP differs from socket

• HTTP runs on a socket
• HTTP and socket are both communication protocols for transferring data between machines over a network. AKA, it is a way for a client and server to communicate with each other
• In HTTP, e.g. a client sends a request to a server and the server sends back a response. AFter this the connection is closed
• HTTP runs on top of the TCP protocol
• Websocket is bidirectional so data flows both ways. In HTTP it is unidirectional ie. can only flow from client to server
• Websocket when the host closes the connection, the connection is terminated at both ends
• To make a request in HTTP, you have to use HTTP request method e.g. GET, PUT, POST, DELETE, PATCH (CRUD)
• HTTP is stateless (after request is finished connection is closed); Websocket is stateful (because the connection stays open after request is finished)