Reading-4-12.md

Socket.io

Web Sockets

1. Web Socket is a communication protocol that allows for two-way data transfer over a single TCP connection.

2. The client sends a handshake request, the server sends a handshake response, then the client and server can send web socket data back and forth

3. Web Sockets provide a standardized way for the server to send content to a client without first receiving a request from that client.

Socket.io Tutorial

1. The io.on event handler handles connection, disconnection, etc., events in it, using the socket object.

2. Console log whenever a connection or disconnect event happens.

3. socket.emit creates and fires a custom event.

Socket.io vs Web Sockets

1. Web Socket is a protocol and socket.io is a library that implements that protocol.

OSI Model Explained

A seven layer standard for getting things to connect to each other.

1. Application: a set of protocols to help application connect, e.g. http or ftp

2. Presentation: establishes data formatting and is responsible for translation (e.g. ASCII to base64), data compression, and encryption.

3. Session: sets up and manages connections, including DNS and authentication/authorization

4. Transport: maintains integrity of transfer, coordinating transfer rates, segmenting and reassembling data, and chacking that all data got the destination.

5. Network: the map that tells you how to get from one node to another.

6. Data Link: Lets individual machines talk to the network

7. Physical: The actual physical machine; converts digital data into a transmission medium, e.g. electrical or radio signals.

TCP Handshakes Explained

1. TCP is a 3 step protocol to establis a connection between te server and client.

   1. The client says "I would like to open a connection. Here's what you need to connect to me."

   2. The server says "Great, you are connected. Here's what you need to make it a two way connection."

   3. The client says "Swell, we now have a two-way connection."