Explain the difference between REST, gRPC, and GraphQL.

REST, gRPC, and GraphQL are different approaches to organizing interaction between client and server.

• REST:

  • Architectural style using HTTP methods (GET, POST, PUT, DELETE).
  • Working with resources via URLs.
  • Easy to use, well-suited for CRUD operations.
  • Data format usually JSON or XML.
  • Lacks strict typing and contracts, which can lead to discrepancies.

• gRPC:

  • Framework from Google for remote procedure calls (RPC).
  • Uses Protocol Buffers for serialization — a compact and fast format.
  • Supports streaming, bidirectional communication.
  • Requires code generation on client and server.
  • Good for microservices and high-performance systems.

• GraphQL:

  • Query language and runtime environment from Facebook.
  • Clients can request exactly the data they need in a single operation.
  • Helps avoid over-fetching and reduces the number of requests.
  • More complex to implement and requires schema and resolvers.

Example:

• REST: GET /users/123 returns data for user 123.
• gRPC: call to GetUser method with parameter 123.
• GraphQL: query { user(id: "123") { name, email } } returns only the user's name and email.

The choice depends on performance requirements, flexibility, and system complexity.