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Gokul G.K.
Gokul G.K.

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Implementing gRPC.

gRPC is a framework developed by Google that provides an efficient, language-independent mechanism for making Remote Procedure Calls (RPCs). Its primary use case is to enhance the performance of these remote calls while maintaining compatibility across different programming languages. Remote procedure calls are crucial in microservices and distributed environments, where large volumes of data are transferred between services.

Core Principle

gRPC is built on several core principles that contribute to its performance and capabilities:

  1. Protocol Buffers: gRPC employs Protocol Buffers for serialization, allowing efficient binary encoding of data. This reduces message size and minimizes the parsing and serialization overhead, resulting in faster communication.
  2. Strongly-typed contracts: gRPC APIs rely on strongly-typed contracts defined with Protocol Buffers that specify the services, methods, and data types available. This establishes a straightforward, consistent interface between the client and the server, minimizing the risk of errors and misunderstandings.
  3. Bi-directional streaming: gRPC facilitates bi-directional streaming, allowing clients and servers to exchange messages simultaneously. This feature enhances communication efficiency, particularly for large or real-time data transfers.
  4. Language-agnostic: gRPC is intended to be language-agnostic, offering official support for various programming languages such as C++, Java, Python, and Go. This flexibility allows developers to select the most appropriate language for their project without facing compatibility issues.

gRPC Core Concept

  • High-performance applications
  • Microservices architecture
  • Applications that require high scalability

gRPC is an excellent choice for performance-centric, scalable APIs in distributed systems, microservices, and real-time applications. It supports multiple languages and platforms with efficient binary data. It's ding. It's ideal for teams experienced in low-level programming and network communication, enabling fast, reliable APIs.

gRPC vs REST API: Comparison Table

Aspect gRPC REST
Protocol HTTP/2 HTTP/1.1 (or HTTP/2)
Message Format Protocol Buffers (Binary) JSON, XML (Text)
Performance โšก Faster (binary serialization) Slower (text parsing)
Payload Size Smaller (~3-10x) Larger
Latency Lower Higher
Bandwidth Usage Lower Higher
Code Generation Automatic (from .proto files) Manual or template-based
Browser Support Limited (gRPC-Web required) Native support
API Style RPC (function calls) Resource-oriented (URIs)
URL Routing Service.Method RESTful paths (/resource/id)
HTTP Methods Uses POST for all GET, POST, PUT, DELETE, PATCH
Caching Difficult (custom logic) Built-in (HTTP caching)
Streaming Bidirectional streaming Request-response only
Connection Persistent (multiplexed) Per-request
Learning Curve Steeper Easier
Ecosystem Growing Mature & established
Documentation Code-generated (proto) Manual documentation
Debugging Harder (binary format) Easier (JSON readable)
Mobile Friendly Good Very good
IoT/Edge Computing Excellent Good
Real-time Features Excellent (streaming) Limited
Interceptors/Middleware Built-in Manual implementation
Error Handling Standardized (gRPC codes) HTTP status codes
Authentication JWT, OAuth, Certificates OAuth, API Keys, JWT
Use Cases Microservices, Real-time, Mobile Public APIs, Web services

Java Implementation

Clone this Git repo.

Run these commands to build and run the applications
mvn clean install
mvn spring-boot:run

Expected outcome

๐Ÿ  ==========================================
๐Ÿ  AquaWorld Pet Store gRPC API
๐Ÿ  ==========================================
๐Ÿ  gRPC Server started on port 9090
๐Ÿ  Test with grpcurl: grpcurl -plaintext localhost:9090 list
๐Ÿ  ==========================================
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Test Application
install grpcurl
grpcurl - Command-line tool for testing gRPC APIs

# macOS
brew install grpcurl

# Linux (requires Go)
go install github.com/fullstorydev/grpcurl/cmd/grpcurl@latest
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Expected Result

com.aquaworld.grpc.auth.AuthService
com.aquaworld.grpc.order.OrderService
com.aquaworld.grpc.payment.PaymentService
com.aquaworld.grpc.product.ProductService
grpc.reflection.v1.ServerReflection
grpc.reflection.v1alpha.ServerReflection
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Follow the ReadMe file to test the remaining functionalities.

gRPC Application

gRPC Design and Best Practices

API Versioning in gRPC

  • Versioning via Proto Packages The recommended approach is to version your API using the package name in your .proto files.
  • Field Numbers Are Sacred In Protocol Buffers, field numbers must never be reused.
  • Don't Delete Instead of removing fields, mark them as deprecated.

Error Handling in gRPC

  • Use gRPC Status Codes Correctly
    • OK โ€“ Success
    • INVALID_ARGUMENT โ€“ Client sent invalid data
    • NOT_FOUNDโ€“ Resource does not exist
    • ALREADY_EXISTS โ€“ Duplicate resource
    • PERMISSION_DENIED โ€“ Authorization failure
    • UNAVAILABLE โ€“ Service temporarily unavailable Avoid returning UNKNOWN or INTERNAL for client-side errors.
  • Rich Error Details via Trailers gRPC offers rich error metadata, enabling clients to handle failures programmatically through structured error details in trailers.

Deadlines, Timeouts, Retries, and Load Balancing

  • Always Set Deadlines A gRPC deadline defines how long a client is willing to wait for a response.
  • Retries Must Be Intentional Retries can improve resilienceโ€”but only when used carefully.
  • Load Balancing Considerations HTTP2'sssHTTP/2'ss long-lived connections, which change how load balancing works.

Choose gRPC if you need:

  • High performance and low latency
  • Efficient mobile/IoT communication
  • Real-time bidirectional streaming
  • Microservices architecture
  • Internal APIs between services
  • Minimal bandwidth usage

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