Call APIs between many microservices 📩

[khanhduzz]

Discuss about the best practice when call between multi services in a spring boot microservices

[khanhduzz]

There are many different ways to make a call between different services in a spring project.

But two common styles of Microservices Communications:

• Synchronous Communication
• Asynchronous Communication

Synchronous Communication

In the case of Synchronous Communication, the client sends a request and waits for a response from the service. The important point here is that the protocol (HTTP/HTTPS) is synchronous and the client code can only continue its task when it receives the HTTP server response.

For example, Microservice1 acts as a client that sends a request and waits for a response from Microservice2.

We can use RestTemplate or WebClient or Spring Cloud Open Feign library to make a Synchronous Communication multiple microservices.

Asynchronous Communication

In the case of Asynchronous Communication, The client sends a request and does not wait for a response from the service. The client will continue executing its task - It doesn’t wait for the response from the service.

**I have a example with RestTemplate here: **
https://www.javaguides.net/2022/10/spring-boot-microservices-communication-using-resttemplate.html#:~:text=Microservices%20Spring%20Boot.%20In%20this%20tutorial,%20we%20will%20learn%20how

[khanhduzz]

• RestClient is a synchronous HTTP client introduced in Spring Framework 6.1 M2 that supersedes RestTemplate. A synchronous HTTP client sends and receives HTTP requests and responses in a blocking manner, meaning it waits for each request to complete before proceeding to the next one.
• Another solution with RestClient to calling in microservices:
  https://www.baeldung.com/spring-boot-restclient#:~:text=Similar%20to%20RestTemplate,%20or%20any%20other%20rest%20client,%20RestClient%20allows