Web Backends

The mental model behind Rust web backends: an async runtime driving a router built from extractors, with Tower's Service/Layer trait pattern composing middleware by nesting rather than by callback chain.

Choosing a framework and a first server.

Routes, methods, and responses.

`State`, `Json`, `Path`, `Query`, and shared data.

`IntoResponse` and error types.

Typed inputs and `validator`.

Real-time endpoints.

The actor-based alternative and when to choose it.

`TestServer`, `tower::ServiceExt`, and fixtures.

Structure, error strategy, and performance.