Reactive Programming

Reactive Manifesto

Reactive Programming is equivalent to Functional programming ++

Asynchronous Programming : vert.x library of Java

Three options available

• handle()
• exceptionally() The above two catches the exception and recovers
• whenComplete() -> Catches Exception but does not recover

Responsive :

There should be an upper limit of response time off an application and an application should respond back to the user within a defined time limit. Eg. For a compute intensive task

• Can design a parallel algorithm (consumes lot of resources)
• Can design async tasks ()

Resilient

In resilient systems, deal with errors gracefully.

Eg. on DB Failures,

• Use Cache
• Use Backup db in replication sync

Elastic

Message Driven

Systems can achieve loose coupling. The components of the system should talk to each

other by asynchronous communication.

CompletableFuture and Reactive Manifest

Responsive

* Asynchronous
* Control return immediately, and the response will be collected whrn its ready
* example CompletableFuture.supplyAsync() runs asynchronously 

Resilent

* No code crash on Exception or Error

Elastic

* Async tasks run is a thread pool (Fork join pool)
* # threads can go up down automatically

Message Driven

* Event driven async tasks interaction
* thenAccept() runs on completion of supplyAsync(event is done and signalling to initiate thenAccept is received)