如何实现2个微服务之间的通信

Question

I had a discussion with my coworker about the way we should implement the communication between 2 microservices. At the moment we have 2 micro services which are depended on each other because my coworker wanted to avoid code duplication by reusing the DTO objects which were used for the REST API.

In a perfect world we would not have any dependencies between the services but in our case it makes sense. In my opinion this couples the services which is worse than duplicating a DTO.

Would you duplicate the DTO in second micro service or are there other solutions?

Answer 1

I suggest you use GRPC (protocol buffer) fro communicating between microservices.

1. create a maven project contains protocol buffers file( it is like a project contains only DTOs wich share among other projects)
2. create how many serivces you like and add protobuf as dependency, it can be even an android project
3. use grpc to communicate with your separated services (in a microservices you should never have any dependencies between the services)

I used to try different solutions for communicating between services including REST APIs but I found GRPC is a perfect world to do so. Also you can have your REST APIs along with GRPC.

Answer 2

For the concept of "Loose coupling", it is not recommend to design microservices communicating each other via REST. Here is a good blogpost to understand the concept. https://www.beeworks.be/blog/2017/rest-antipattern.html
One way is to use a message broker as an enterprice bus.
If you use message broker, - you may use RPC calls to request one microservice to another. - or you may publish an event(pub/sub)
Here is a good blogpost to understand of concepts of using message broker in microservice infrastructure.
https://dev.to/matteojoliveau/microservices-communications-why-you-should-switch-to-message-queues--48ia

Answer 3

Even in this post there were different opinions on how to share models between micro services and how to communicate. I would say the clean solutions is explained in this post.

Micro services: shared library vs code duplication