Long Polling

• Request is taking long, I’ll check with you later But talk to me only when it's ready

• moving short polling from the client to the server

Use case

• Short polling and req/resp not ideal

• Same usecase as short polling But too chatty

  • A request takes long time to process

  • The backend want to sends notification

• Kafka uses it

How

• Client sends a request

• Server responds immediately with a handle

• Server continues to process the request

• Client uses that handle to check for status

• Server DOES not reply until it has the response

  • The connection is still there but server only responds when ready to

• So we got a handle, we can disconnect and we are less chatty

• Some variation has timeouts too

Pros

• less chatty

• Backend friendly - dont overwhlem it

• client can disconnect

Cons

• not real time

Links

• https://www.baeldung.com/spring-mvc-long-polling