APIkäitlejad

APIkäitlejad, Estonian software terms for API handlers, are the server-side components that process API requests. They receive requests, route them to the appropriate logic, enforce access controls, validate inputs, invoke business services, and compose responses. They can be implemented as route handlers, controllers, or middleware within web frameworks and cover REST, GraphQL, and gRPC APIs.

Typical responsibilities include authentication and authorization, input validation and sanitation, deserialization and serialization, error handling and mapping to standard status codes, rate limiting and caching, data transformation, logging, and auditing. They participate in versioning, content negotiation, and maintaining stable API contracts through documentation and tests.

In architecture, API handlers may reside directly in the application or behind an API gateway. A gateway can handle cross-cutting concerns such as authentication, throttling, and routing, while individual handlers implement business logic. Common patterns include middleware pipelines that compose multiple handlers and the controller pattern that maps routes to actions. Contract-driven development using specifications like OpenAPI is common.

Security and reliability considerations include thorough input validation, safe authentication and authorization checks, avoiding leakage of sensitive information in errors, and protection against injection attacks. Performance aspects include non-blocking or asynchronous handling, streaming where suitable, pagination, efficient serialization, and observability through logging and metrics.

See also API gateway, middleware, REST, GraphQL, and gRPC.