Feign as a declarative REST client
In the Booking microservice, there is a synchronous call to Fare. RestTemplate is used for making the synchronous call. When using RestTemplate, the URL parameter is constructed programmatically, and data is sent across to the other service. In more complex scenarios, we will have to get to the details of the HTTP APIs provided by RestTemplate or even to APIs at a much lower level.
Feign is a Spring Cloud Netflix library for providing a higher level of abstraction over REST-based service calls. Spring Cloud Feign works on a declarative principle. When using Feign, we write declarative REST service interfaces at the client, and use those interfaces to program the client. The developer need not worry about the implementation of this interface. This will be dynamically provisioned by Spring at runtime. With this declarative approach, developers need not get into the details of the HTTP level APIs provided by RestTemplate.
The following code snippet is the existing...
