How to build a two-way network messaging architecture?

Question

Algorithms

I'm interested in a pattern that will allow you to ask the user for missing data and at the same time completely separate the client and server logic.
Example:

• user performs an action
  
• the client makes a request to the server
  
• the server processes the request, at some point a clarification is required from the user
  
• the server makes a request to the client
  
• user adds new data
  
• the client makes a request to the server
  
• the server continues processing the request and returns a response
  
• the result is displayed on the client
  

Answer 1

Read about the Finite State Machine.