Difference between GraphqQL and Rest API

GraphQL and REST API are two different approaches to designing and interacting with APIs. Here's a detailed comparison of their key differences:

REST API (Representational State Transfer)

Overview

• Architecture Style: REST is an architectural style that uses a stateless client-server protocol (usually HTTP) for communication.
• Endpoints: Resources are exposed as URLs (endpoints), and operations (GET, POST, PUT, DELETE) are performed using HTTP methods.
• Data Transfer: Typically returns JSON or XML data.
• Client-Driven: Server decides what data to return based on URL and HTTP method.
• Caching: Easily cacheable using HTTP caching mechanisms (like ETag, Last-Modified headers).

Characteristics

• Data Fetching: Multiple endpoints for different resources (e.g., /users, /posts).
• Over-fetching: May retrieve more data than needed.
• Under-fetching: May require multiple requests to fetch related resources.
• Schema: Not explicitly defined; documentation typically describes available endpoints and data structures.

Example Request

GET /users/123

GraphQL

Overview

• Query Language: GraphQL is a query language and runtime for executing queries against a GraphQL server.
• Single Endpoint: All requests go to a single endpoint (/graphql by convention), and queries are sent as JSON payloads.
• Client-Defined: Clients request exactly the data they need using a schema (defined by types and fields).
• Strongly Typed: GraphQL schemas define types and relationships between them.
• Versioning: No need for versioning endpoints; clients can request new fields as needed.

Characteristics

• Data Fetching: Single endpoint for flexible data fetching with queries.
• Under-fetching: Clients fetch exactly what they need.
• Over-fetching: No extra data; clients specify required fields in the query.
• Schema: Explicitly defined in SDL (Schema Definition Language); strongly typed with types, fields, and relationships.

Example Request

query {
  user(id: "123") {
    name
    email
    posts {
      title
      content
    }
  }
}

Differences

1. Data Fetching:

   • REST: Multiple endpoints; each endpoint returns fixed data structures.
   • GraphQL: Single endpoint; clients request specific data structures with queries.

2. Flexibility:

   • REST: Less flexible for clients; clients depend on server-defined endpoints.
   • GraphQL: Highly flexible; clients request exactly what they need, reducing over-fetching and under-fetching.

3. Network Efficiency:

   • REST: May lead to over-fetching or under-fetching.
   • GraphQL: Efficient data retrieval; reduces network overhead by fetching only necessary data.

4. Schema and Type Safety:

   • REST: No strict schema definition; relies on documentation.
   • GraphQL: Strictly typed schema; clients know what data they can request and receive.

5. Versioning:

   • REST: Often requires versioning of endpoints.
   • GraphQL: No versioning of endpoints; clients evolve queries over time.

6. Tooling and Ecosystem:

   • REST: Mature ecosystem with extensive tooling and frameworks.
   • GraphQL: Growing ecosystem with tools for schema validation, code generation, and more.

Use Cases

• REST API:

  • Well-suited for simple, resource-based CRUD operations.
  • Good for public APIs where backward compatibility and documentation are critical.

• GraphQL:

  • Best for applications needing flexible, efficient data fetching.
  • Ideal for complex querying requirements, microservices, and applications with evolving data needs.