Proof of Concept (PoC): Software Architecture - Software Interfaces [1] Interaction Styles - Remote Procedure Call - gRPC

Description:

This project is intended to evaluate a PoC for the Remote Procedure Calls Pattern(RPC) interaction style created by Google (2015) as a Synchronous Messaging Pattern for Cloud Native Applications that follows the RPC pattern [3].

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Objectives:

• Define the ProtoBuffs for 2 services: customer and restaurant.
• Integrate them with a database in which customers and restaurant dishes information are stored.
• Publish both services to be consumed by a client like BloomRPC [6].
• Grant the communication from the customer service to the restaurant service in order to get the total amount for the billing account to pay.

gRPC Diagram [5]:

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Technologies used:

• Java 1.8 as a programming language with maven.
• grpc-netty-shaded: HTTP/2 transport library.
• grpc-protobuf, and protobuf-maven-plugin: for compilation of the proto files to the protocolBuffers model to be implemented by the services.

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How to test it?

• Open the project and execute mvn clean install and verify that the protobuf model gets generated as it is shown in the image bellow:

• Open the project and right click in both CustomerServer.java and RestaurantServer.java classes.
• Download BloomRPC to be used as a client to make requests to both services [6].
• Load both the customer.proto and the restaurant_dish.proto in the BloomRPC interface:
• Specify the ports for each service as it is shown in the image bellow and execute an unary call per each service. Verify that the dishes_amount proto field that representes the billing account to pay has the value of the sum of all the dishes associate it with the customer "william"

Customer:

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Restaurant:

restaurant_dish.proto

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Results:

As it was shown in the previous screenshots, the CustomerService was able to communicate to the Restaurant one through a Channel used in the RestaurantClient and the serialization and deserialization was efficiently performed by both services.

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Conclusions:

• gRPC was implemented as a Synchronous Pattern of communication as it is suggested in [3].
• However, a more efficient implementation (asynchronous one) is preferred for those kind of applications following the Microservices Architectural Style.
• Nevertheless, the implementation of both services allows developers to manage Software Interfaces Interaction Styles as it were local methods as they are getting used to.

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References:

1. Software Architecture in Practice, 4th Edition, Len Bass, Paul Clements, Rick Kazman, 2022, pages 217-227
2. Building Java Microservices with gRPC
3. Design Patterns for Cloud Native Applications, 1st edition, Kasun Indrasiri, Sriskandarajah Suhothayan, 2021, pages 57-72
4. gRPC Up & Running, 1st Edition, Kasun Indrasiri, Danesh Kuruppu , 2020
5. Introduction to gRPC
6. BloomRPC client