EIP – Request/Response Integration Pattern

Summary

This post will summarise the various Message Construction patterns. This isn’t a comprehensive list, but patterns that have been widely adopted by the integration community. Some of these Message Construction patterns can also be classed under Message Exchange patterns.

Request-Reply / Request-Response

Request-Reply is a message exchange pattern in which a requester sends a request message to a replier system that receives and processes the request, ultimately returning a message as a response. This is a simple, but powerful messaging pattern that allows two applications to have a two-way conversation with one another over a channel. This pattern is especially common in client-server architectures. — Wikipedia

Transmission Type: Synchronous

In a practical use case, let’s assume you have a CRM system, where you want to query the CRM to return a list of customers. Your message will include some sort of request to the CRM system, but also the target system will respond to your request by sending you the customer data in return.

Microsoft’s online documentation goes into great lengths to explain this pattern here: https://docs.microsoft.com/en-us/azure/architecture/patterns/async-request-reply

Logic Apps Design Pattern

This pattern uses the HTTP request trigger. A caller makes a request, waits for some business logic to process then receives a response.

The implementation below uses a Delay activity to reproduce some processing.

Finally, a Response activity sends a message back to the caller.