What is GraphQL?
Developed by Facebook in 2012 and open-sourced in 2015, GraphQL provides a flexible alternative to REST by letting applications specify the structure of responses in a single request. GraphQL is both a query language and a server-side runtime for executing those queries. Instead of multiple endpoints returning fixed data structures, GraphQL exposes a single endpoint that returns data shaped by the client’s query. GraphQL APIs are strongly typed, meaning every field and object has a defined type. This allows for validation, autocompletion, and introspection tools that improve developer productivity.
How GraphQL Works
- Schema Definition:
The API schema describes available data types and relationships using the GraphQL Schema Definition Language (SDL). - Client Query:
The client sends a query specifying which fields it needs and how they relate. - Execution Engine:
The GraphQL server resolves each field by calling the appropriate data sources or functions. - Response:
The server returns a structured JSON object mirroring the query format. - Mutations & Subscriptions:
GraphQL supports data modification (mutations) and real-time updates (subscriptions) via WebSockets or similar protocols.