Writing an API

In this section, we will write the API using Protocol Buffer (Protobuf) for a payment service. If you recall, this is the piece that you haven’t yet implemented in the sample e-commerce app.

Before writing the API, let’s set up the Gradle project.

Setting up the project

The code for this chapter will contain three projects under the Chapter11 directory – the API, server, and client:

• API: This is a library project that contains the .proto file and its generated Java classes packaged in a JAR file. This project will generate the payment-gateway-api-0.0.1.jar library artifact, which you will publish in a local repository. This library will then be used in both the server and client projects.
• Server: This project represents the gRPC server, which will implement the gRPC services and serve the gRPC requests.
• Client: This project contains the gRPC client, which will call the gRPC server. To kick off the inter-service communication...