Messaging Patterns

Request-Response

Model

• Client sends a request
• Server parses the request: Where does a request begin and end?
• Server processes the request: Example, Deserializing JSON and then processing.
• Server sends a response
• Client parses the response and consume

Anatomy

• Client and server need to define and agree upon the request/response structure.
• Request/response has a boundary
• Defined by protocol and message format.

Where is it used?

• Web, HTTP, DNS, SSH.
• Remote Procedure Call (RPC)
• SQL and database protocols
• APIs (REST/SOAP/GraphQL)

Where it doesn't work well?

• Notification Service
• Chat Applications
• Very Long requests - What if client disconnects?

Polling

Or short-polling.

• Request takes long time to process

Push

Use case

• Client wants real-time notification from server.

Examples

• User just logged in
• Message just recieved (chat app)

Cons

• Client must be online
• Client must be able to handle