Spring REST vs gRPC: Which to Choose? Interview preparation

Deciding between Spring REST and gRPC is a crucial step in choosing the right approach for your application architecture. Both technologies are commonly used for communication in distributed systems, but they cater to different needs and use cases. REST has long been a popular choice for building APIs, especially with its simplicity and browser-friendliness. On the other hand, gRPC has emerged as a modern alternative, offering high-performance Remote Procedure Call (RPC) capabilities ideal for microservices and internal APIs.

This blog will break down the differences between Spring REST and gRPC across various dimensions, helping you choose the right one for your project.

Table of Contents

1. Protocol and Encoding (JSON vs Protobuf)
2. Spring Boot REST Setup vs Spring Boot gRPC
3. RESTful Endpoints vs RPC Calls
4. Browser and Mobile Support
5. Performance Benchmarks (Latency + Payload)
6. Bi-Directional Streaming in gRPC
7. Load Balancing and Retries
8. Monitoring and Observability
9. Use Cases: Microservices, IoT, Internal APIs
10. REST-to-gRPC Migration Tips
11. FAQs

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1. Protocol and Encoding (JSON vs Protobuf)

REST

• Protocol: REST uses HTTP/HTTPS as the underlying protocol, making it inherently stateless and cacheable.
• Encoding: REST APIs most commonly exchange data in JSON format, which is human-readable but relatively bulky.

gRPC

• Protocol: gRPC uses the HTTP/2 protocol, which supports multiplexing, making it faster and more efficient in handling multiple simultaneous requests and responses.
• Encoding: gRPC employs Protocol Buffers (Protobuf) for data serialization. Protobuf is highly efficient, producing compact binaries that reduce payload size significantly compared to JSON.

Key Takeaway: JSON is more human-friendly and suited for browser-based apps, while Protobuf is optimized for performance and data efficiency.

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2. Spring Boot REST Setup vs Spring Boot gRPC

Spring Boot REST Setup

• Ease of Use: Setting up REST in Spring Boot is straightforward. Developers can define APIs using the @RestController annotation.
• Tooling: Swagger/OpenAPI makes managing and documenting REST APIs simple.
• Example:

   @RestController
   public class HelloController {
       @GetMapping("/hello")
       public String sayHello() {
           return "Hello, World!";
       }
   }
   ```  

### Spring Boot gRPC Setup  
- **Learning Curve:** gRPC setup in Spring Boot requires additional configuration and understanding of `.proto` files.  
- **Example:** Define your service in a `.proto` file:
   ```proto
   service HelloService {
       rpc SayHello (HelloRequest) returns (HelloResponse);
   }

• Use Spring integration libraries like grpc-spring-boot-starter for seamless configuration.

Key Takeaway: REST is easier to get started with, while gRPC setup involves more complexity but pays off in performance-critical applications.

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3. RESTful Endpoints vs RPC Calls

RESTful Endpoints

• Based on resources and operates via HTTP methods like GET, POST, PUT, DELETE.
• Example API endpoint for fetching users:

   GET /users/123

RPC Calls

• RPC is focused on procedures rather than resources. Instead of endpoints, you directly call methods like:

   SayHello(request)

Key Difference: REST aligns with the traditional resource-based API design, whereas gRPC offers a more granular approach through method calls.

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4. Browser and Mobile Support

REST

• Designed to work seamlessly with browsers and is supported natively across all modern frontend frameworks like React and Angular.

gRPC

• Works natively with backends but is challenging in browser environments due to Protobuf serialization. Tools like gRPC-Web help bridge the gap for browser support.

Key Takeaway: REST edges out gRPC for browser-based applications, while gRPC is preferred for backend systems and microservices.

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5. Performance Benchmarks (Latency + Payload)

REST

• JSON payloads are text-based, making them larger and slightly slower to process.
• REST over HTTP typically has higher latency due to statelessness and overhead.

gRPC

• Protobuf ensures compact binary payloads, significantly reducing bandwidth usage.
• HTTP/2 enables multiplexing, reducing latency for high-concurrency environments.

Benchmark Insight: The smaller payload size and HTTP/2 efficiency make gRPC faster and more cost-effective for high-traffic use cases.

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6. Bi-Directional Streaming in gRPC

One of gRPC’s standout features is bi-directional streaming, enabling real-time communication between clients and servers.

Example Use Case

A stock-trading application can use gRPC streams to send updates to the client continuously in real-time.

REST’s Limitation

While REST supports polling or server-sent events, these approaches are less efficient compared to gRPC’s streaming capabilities.

Key Takeaway: Choose gRPC if your app relies on real-time data or requires continuous communication.

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7. Load Balancing and Retries

REST

• Relies on API gateways like NGINX or AWS API Gateway for load balancing and retries.

gRPC

• Has built-in support for client-side load balancing and retries, offering better distributed system behavior without external infrastructure.

Key Takeaway: gRPC simplifies operational complexity with built-in features for load balancing and failover handling.

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8. Monitoring and Observability

REST

• Tools like Spring Actuator and Prometheus easily integrate to provide metrics and monitoring.
• Logging frameworks allow detailed observability.

gRPC

• Monitoring gRPC services requires tools that support Protobuf parsing, such as Jaeger for tracing or Prometheus with custom exporters.

Key Takeaway: Although both can be monitored effectively, REST benefits from broader industry support for observability tools.

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9. Use Cases: Microservices, IoT, Internal APIs

REST Use Cases

• Public APIs: Ideal for third-party services and browser interactions.
• Mobile Backends: Simple, JSON-based communication.

gRPC Use Cases

• Microservices: Efficient for backend-to-backend communication.
• IoT Applications: Compact Protobuf payloads are perfect for bandwidth-constrained environments.
• Game Development: Real-time, low-latency multiplayer interactions.

Key Takeaway: REST is the default for public-facing APIs, whereas gRPC shines in performance-sensitive, internal environments.

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10. REST-to-gRPC Migration Tips

1. Prepare Your Services: Identify REST APIs that handle internal traffic or performance-heavy tasks.
2. Define Protobuf Files: Convert JSON schemas into .proto definitions.
3. Integrate gRPC Gradually: Use libraries like grpc-gateway to expose gRPC services as REST endpoints, enabling backward compatibility.
4. Test Performance Gains: Set up benchmarks to justify the migration.

Pro Tip: Avoid migrating public APIs to gRPC unless absolutely necessary due to browser compatibility concerns.

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FAQs

Can you combine REST and gRPC in the same application?

Yes, you can. Use gRPC for internal communication and REST for external-facing APIs via tools like gRPC-gateway.

Which is easier to debug, REST or gRPC?

REST is easier to debug due to human-readable JSON payloads. gRPC debugging requires Protobuf parsers or specialized tools.

When should I avoid gRPC?

Avoid gRPC for browser-based apps or environments where JSON and REST are standard. gRPC is better suited for internal purposes.

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Summary

The choice between Spring REST and gRPC depends on your application’s requirements. REST remains the top choice for public-facing APIs due to its simplicity, browser compatibility, and widespread support. On the other hand, gRPC excels in backend communication with its high-performance capabilities, small payloads, and bi-directional streaming support.

By understanding the strengths and trade-offs of each, you can make informed decisions that align with your project goals and technical constraints! For more insights, explore the Spring REST documentation or check out gRPC examples.