WebSockets technology is a bidirectional, full-duplex protocol for communication between client and server over the web. It has been standardized in 2011 and its fully compatible with HTTP. This protocol enables realtime applications such as chatting, notifications, live feed , multiplayer gaming and otheruse cases.

In this video we will explain what WebSockets are and why it was invented. we will then build a server and client using WebSockets. We will also talk about the pros and cons of WebSockets, and discuss some alternatives to this technology 

Chapters
0:00 Intro
2:00 HTTP
5:40 WebSockets
8:00 WebSockets Handshake
11:20 WebSockets Usecases
14:30 WebSockets Example Code
36:40 WebSockets Pros and Cons 
42:10 Do you have to use webSockets?

Source Code in the video for WebSockets 
https://github.com/hnasr/javascript_playground/tree/master/websocket-demo


HTTP
  * talk about request-response show a slide. Client initiate request all the time. Imagine building a chatting app? 

WebSockets 
- Slide showing bidrectional full duplex  standard web 
- 
How WebSockets Work?
- WebSockets handshake 
- Initial request is always HTTP which we all know creates a tcp connection, that request then http upgrade tells the server to use it as bidirectional.  
- Once done switches to binary protocol. 
- Ws:// wss:// protocol 

WebSocket use cases
- Chatting
- Live feeds
- Multiplayer gaming
- Progress bar/ logging/ uploading..

- WebSockets example (Server/Client) 
- WebServers Pros and Cons  

Pros
1. Full-duplex no need for constant polling  
2. compatible with HTTP, so proxies know to deal with it
3. Firewalls won’t block it doesn’t use a special port
Cons
1. Proxying is tricky, lots of proxies and transparent proxies don’t support it yet
2. Layer 7 load balancing is tricky, timeouts on the load balancer. 
3. More complicated to implement (simple telnet use HTTP)
4. Not ideal for all use cases - (microservices)


- Do you have to use Web Sockets ? ( alternatives  ) 
It is important to note that WebSockets is not the only HTTP realtime based solution, there are other ways to achieve real time such as eventsource, and long polling. 

- Load Balancing with WebSockets (bonus) 
- layer 4 
- Layer 7 (tunnel) 

Longpolling
Eventsource
WebSockets 

 
Sources: 

https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers

https://www.ably.io/concepts/websockets

https://link.medium.com/ljsSOsnW6Y

https://blog.stanko.io/do-you-really-need-websockets-343aed40aa9b



Cards
HTTP Crash Course https://www.youtube.com/watch?v=0OrmKCB0UrQ
TLS https://www.youtube.com/watch?v=AlE5X1NlHgg
What is a Web Servers https://www.youtube.com/watch?v=JhpUch6lWMw
Layer 4 vs Layer 7 Load Balancing https://www.youtube.com/watch?v=aKMLgFVxZYk





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