Reactive Programming (React to something)

It is a declarative programming paradigm to build asynchronous processing pipelines.

Traditional use cases

• user events: When a user clicks a button.
• I/O Responses

What is the execution flow of the server-side web request?

1. Request comes into the server. Server takes a thread from the thread pool to handle the request.
2. that thread does the processing
3. finally return the response to that waiting client.

What the criteria do modern application wants

• handle high data volume
• high-responsive and optimized usage
• optimize hardware resource to reduce cloud hosting cost