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name: domain-web description: "Use when building web services. Keywords: web server, HTTP, REST API, GraphQL, WebSocket, axum, actix, warp, rocket, tower, hyper, reqwest, middleware, router, handler, extractor, state management, authentication, authorization, JWT, session, cookie, CORS, rate limiting, web 开发, HTTP 服务, API 设计, 中间件, 路由" globs: ["**/Cargo.toml"]

Web Domain

Layer 3: Domain Constraints

Domain Constraints → Design Implications

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Critical Constraints

Async by Default

CopyRULE: Web handlers must not block
WHY: Block one task = block many requests
RUST: async/await, spawn_blocking for CPU work

State Management

CopyRULE: Shared state must be thread-safe
WHY: Handlers run on any thread
RUST: Arc<T>, Arc<RwLock<T>> for mutable

Request Lifecycle

CopyRULE: Resources live only for request duration
WHY: Memory management, no leaks
RUST: Extractors, proper ownership

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Trace Down ↓

From constraints to design (Layer 2):

Copy"Need shared application state"
    ↓ m07-concurrency: Use Arc for thread-safe sharing
    ↓ m02-resource: Arc<RwLock<T>> for mutable state

"Need request validation"
    ↓ m05-type-driven: Validated extractors
    ↓ m06-error-handling: IntoResponse for errors

"Need middleware stack"
    ↓ m12-lifecycle: Tower layers
    ↓ m04-zero-cost: Trait-based composition

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Framework Comparison

Key Crates

Design Patterns

Code Pattern: Axum Handler

Copyasync fn handler(
    State(db): State<Arc<DbPool>>,
    Json(payload): Json<CreateUser>,
) -> Result<Json<User>, AppError> {
    let user = db.create_user(&payload).await?;
    Ok(Json(user))
}

// Error handling
impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        let (status, message) = match self {
            Self::NotFound => (StatusCode::NOT_FOUND, "Not found"),
            Self::Internal(_) => (StatusCode::INTERNAL_SERVER_ERROR, "Internal error"),
        };
        (status, Json(json!({"error": message}))).into_response()
    }
}

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Common Mistakes

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Trace to Layer 1

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Related Skills