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asynchronousmicroservicescommunicationsoasynchronous
Kenaka
Kenaka

Reputation: 59

Asynchronous communication between Microservices

For the last week I've been researching a lot on the microservice architecture pattern and its requirements and constraints. The majority of ressources suggest to use event buses/message brokers (asynchronous communication) to communicate between microservices rather than using REST API endpoints. Synchronous calling would result in a higher response time and may cause cascading failure in case of a particular microservice failing in the chain.

Question:

Let's say the user requests a particular functionality or page on a website/mobile app which then needs to fetch data from multiple microservices and use theire respective functionalities to provide the desired outcome. But to achieve the desired outcome (response to client) ALL the services need to do their work before the backend sends the response back to the client (website/mobile app).

But if we use asynchronous service requests - which means the calling service doesnt wait for a response and would send its own response back to the client without getting the data from the asynchronously called service - the outcome might not be complete if an asychronously called service doesnt respond in time (service is unavailable or network issues). This would mean that the backend will send an incomplete response back to the client which is not acceptable.

How can I deal with this issue or did I get the concept wrong?

I'm thankful for every answer

Upvotes: 1

Views: 996

Answers (1)

Levi Ramsey
Levi Ramsey

Reputation: 20611

If it's absolutely essential that a request gets a full response (i.e. that the request is synchronous), that's a strong argument in favor of the service stitching together synchronous requests and responses (and potentially needing to handle rollback in cases of partial success etc.).

Many requests don't fall into that pattern, though. For instance, a response might well be interpretable as "we've received your request and the operation will be performed. You can track the progress of your operation by using this request ID"; such an approach fits well with asynchronous messaging.

Upvotes: 2

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