Understanding the asynchronous communication design pattern

Earlier in this chapter, we identified one of the reactive design principles as asynchronous message-driven communication. That principle is core to the asynchronous communication design pattern:

1. First, the client sends a request message to a server
2. Next, the server sends an acknowledgement message to the client immediately and then takes whatever time is necessary to process the request
3. Once the request is fully processed, the response message is sent from the server to the client

This diagram illustrates three components of asynchronous communication:

Asynchronous communication design pattern implementation—overview

This method of communication is efficient because it allows the client to send multiple request messages to the server and not dedicate processing resources, and anticipate a response message from...