Server-Sent Events w/ crypto price ticks

This is a simple demonstration of Server-Sent Events & WebSockets based on a Node.js backend and a HTML/JS frontend.

Server-Sent events (SSE) is a specification for implementing server-side push events to web frontend applications, through plain-old HTTP.

This is best contrasted with WebSockets, which offer a full-duplex messaging channel over a custom protocol, operating within a single TCP connection w/ an HTTP-compatible handshake.

Setup

clone the project and perform the following commands

npm install 
node server.js

Trying out the demo

Navigate to http://localhost:8000 and watch crypto rise 🚀🚀🚀

On this page you have the opportunity to switch between SSE and WebSockets for ticker events. It will do the same thing, but with the two different technologies.

for SSE the client opens a connection to /events endpoint, which the server keeps open
for WebSockets, a connection to http://localhost:40510 is used

SSE vs WebSockets

Advantages of SSE:

Transported over simple HTTP instead of a custom protocol
Can be poly-filled with javascript to "backport" SSE to browsers that do not support it yet.
Built in support for re-connection and event-id
- try restarting our Node.js server.
- when using SSE, the tick events will work great again
- with the switch set to WebSockets, thats not the case
No trouble with corporate firewalls doing packet inspection
Ideally used for stock ticker or browser notifications

Advantages of WebSockets:

Real time, two directional communication.
Native support in more browsers
Supports binary data as well
No connection limit
- SSE is limited to 6 connections per browser + domain
Ideally used for chat applications