# Server Sent Events

* one request, but the response is very long, never ending
* client can handle and parse this response
  * spot the chunks and initiate some code
* Using content-type: Chunk-stream or event-stream
* Designed for http and req/resp
* overcomes issues of push

## What

* A response has start and end
* Client sends a request
* Server sends logical events as part of response
  * event has a start and end which the client can recognise and unfold to use
* Server never writes the end of the response
* It is still a request but an unending response
* Client parses the streams data looking for events
* Works with request/response (HTTP)

## PRo

* real time
* Compatible with req/resp

## Cons

* Client must be online
* Might not be able to handle all these events
  * similar to push
  * client might disconnect
  * The server will have to handle this problem
* polling is preferred for lighter clients
* Using http 1.1 issue
  * can only make 6 connections to a domain
  * only one request per connection, and until the request is finished cannot send anything else on that connection
  * so if all 6 req are server side events, it will be blocked
* Better to use http2
  * can send multiple streams in same connnection