Principle:OpenHands OpenHands Middleware Configuration
| Knowledge Sources | |
|---|---|
| Domains | Server_Architecture, SaaS_Infrastructure |
| Last Updated | 2026-02-11 21:00 GMT |
Overview
Configuring HTTP middleware layers for authentication, caching, and rate limiting ensures that every incoming request passes through a consistent chain of cross-cutting concerns before reaching business logic handlers.
Description
The Middleware Configuration principle governs how request-processing layers are stacked around the core application. In a SaaS server, multiple middleware components handle orthogonal responsibilities: authentication cookie management verifies and attaches session tokens, rate limiting protects against abuse, and caching middleware reduces redundant computation. Each middleware layer receives the incoming request, may modify it or short-circuit the response, and then passes control to the next layer in the chain. The ordering of these layers matters: authentication typically runs first to establish identity, followed by rate limiting to enforce quotas per identity, and then caching to optimize repeated requests.
Usage
Apply this principle when the server requires multiple cross-cutting concerns that should be applied uniformly across all or most endpoints. Middleware configuration is essential when authentication must be enforced globally, when rate limiting must protect backend resources, or when response caching must be applied transparently. Each middleware layer should be independently testable and configurable.
Theoretical Basis
The chain of responsibility pattern provides the theoretical foundation for middleware configuration. Each middleware component in the chain has the opportunity to inspect, modify, or reject a request before delegating to the next handler. This pattern decouples the processing logic from the routing logic: endpoint handlers remain focused on business logic while middleware handles authentication, authorization, rate limiting, and other infrastructure concerns. The sequential nature of the chain ensures predictable execution order, and the ability to short-circuit (returning a response without calling the next handler) provides efficient error handling for unauthorized or rate-limited requests. In ASGI frameworks like FastAPI, middleware is implemented as callable wrappers that receive a request and a call_next function, enabling clean composition of processing layers.