REST vs RPC

In distributed systems, both REST (Representational State Transfer) and RPC (Remote Procedure Call) are widely used communication paradigms, but they differ in terms of design philosophy, usage, and complexity. Here’s a comparison of REST vs RPC:

1. Conceptual Model

• REST:

  • Based on resources.

  • Clients interact with resources (such as users, files) via standard HTTP methods (GET, POST, PUT, DELETE).

  • Follows stateless communication, where each request from the client must contain all necessary information to be understood by the server.

  • Typically used with JSON or XML payloads.

• RPC:

  • Based on actions or procedures.

  • Clients invoke procedures or methods on the server, similar to calling a function in local code.

  • Focuses on actions (CreateUser(), UpdateBalance()) rather than resources.

  • Payload format is often protocol-specific (e.g., JSON-RPC, XML-RPC, gRPC).

2. Ease of Use

• REST:

  • Simpler to use and more intuitive for CRUD (Create, Read, Update, Delete) operations due to resource-based design.

  • Easier to consume from clients, especially when dealing with web-based applications, as it uses standard HTTP methods and status codes.

• RPC:

  • Feels more natural when thinking in terms of actions or procedures.

  • More complex to design and implement because it often requires defining specific methods and payload formats for each procedure.

3. Protocol

• REST:

  • Primarily uses HTTP.

  • Uses URIs to represent resources and HTTP methods to interact with them.

  • Commonly works with JSON, XML for data transmission.

• RPC:

  • Can use various protocols such as HTTP, TCP, or more specialized ones like gRPC (which uses HTTP/2).

  • With gRPC, Protocol Buffers (Protobuf) is a common format for data serialization, allowing for smaller and faster messages than JSON.

4. Flexibility vs Strictness

• REST:

  • Offers more flexibility as it's not tied to a specific protocol beyond HTTP.

  • Follows a uniform interface, making it loosely coupled and adaptable.

• RPC:

  • More strict and rigid, as the client and server must agree on method names, parameter formats, and behavior.

  • More tightly coupled since any change in the service definition or methods on the server requires clients to be updated.

5. Use Cases

• REST:

  • Best suited for applications that revolve around manipulating resources, such as CRUD operations in web services.

  • Ideal for web-based APIs and microservices where simplicity and resource-oriented design are prioritized.

• RPC:

  • Better suited for applications where actions need to be invoked directly on the server, such as in complex backend services.

  • Often used in high-performance, low-latency environments (e.g., gRPC for inter-service communication in microservices).

6. Performance

• REST:

  • Can be slower due to the overhead of HTTP and the verbosity of data formats like JSON.

  • HTTP/1.1 might limit performance due to the lack of advanced features like multiplexing.

• RPC:

  • In the case of gRPC, it provides better performance with HTTP/2 features like multiplexing, header compression, and binary serialization using Protobuf.

  • Generally faster and more efficient, especially in high-volume, low-latency environments.

7. Error Handling

• REST:

  • Leverages standard HTTP status codes (e.g., 200 OK, 404 Not Found, 500 Internal Server Error) to signal success or failure.

  • Simpler, as clients are already familiar with HTTP error codes.

• RPC:

  • Error handling can be more complicated, as it often requires custom status/error codes or may rely on protocol-specific error formats.

  • gRPC, for example, has a well-defined set of error codes but can still be less intuitive compared to REST.

8. Tooling and Ecosystem

• REST:

  • Strong ecosystem with a wide range of tools (Postman, Swagger/OpenAPI) for documentation, testing, and client generation.

  • Works seamlessly with web technologies due to its alignment with HTTP and RESTful principles.

• RPC:

  • Requires more specialized tooling for each RPC framework (e.g., gRPC tools for generating client/server code).

  • While gRPC has growing support, it is less universal compared to REST in the web development ecosystem.

Summary Table

Aspect	REST	RPC
Model	Resource-based	Action/procedure-based
Ease of Use	Simple for CRUD, intuitive for web APIs	Feels natural for direct method invocations
Protocol	HTTP	HTTP, TCP, gRPC
Flexibility	Loosely coupled, flexible	Tightly coupled, rigid
Performance	Good, but can be slower (especially with JSON)	High performance, especially with gRPC
Error Handling	Standard HTTP status codes	Custom or framework-specific error handling
Use Case	CRUD, web APIs	High-performance microservices, backend actions
Tooling	Strong ecosystem, widely supported	Requires specific tooling (gRPC, Protobuf)

Key Takeaways:

• Use REST when building web-based services or APIs focused on manipulating resources with a focus on simplicity and interoperability.

• Use RPC when performance, tight control over procedures, or more complex service-to-service communication is required (e.g., in microservices or backend systems).