Trait Middleware 

pub trait Middleware: Send + Sync {
    // Provided methods
    fn on_request(
        &self,
        _ctx: &McpContext,
        _request: &JsonRpcRequest,
    ) -> McpResult<MiddlewareDecision> { ... }
    fn on_response(
        &self,
        _ctx: &McpContext,
        _request: &JsonRpcRequest,
        response: Value,
    ) -> McpResult<Value> { ... }
    fn on_error(
        &self,
        _ctx: &McpContext,
        _request: &JsonRpcRequest,
        error: McpError,
    ) -> McpError { ... }
}

Middleware hook trait for request/response interception.

This is intentionally minimal: synchronous hooks only, with simple short-circuit and response transform capabilities. See the module-level documentation for ordering semantics.

Provided Methods

fn on_request( &self, _ctx: &McpContext, _request: &JsonRpcRequest, ) -> McpResult<MiddlewareDecision>

Invoked before routing the request.

Return Respond to skip normal dispatch and return a custom result.

fn on_response( &self, _ctx: &McpContext, _request: &JsonRpcRequest, response: Value, ) -> McpResult<Value>

Invoked after a successful handler result is produced.

Middleware can transform the response value (or return an error).

fn on_error( &self, _ctx: &McpContext, _request: &JsonRpcRequest, error: McpError, ) -> McpError

Invoked when a handler or middleware returns an error.

Middleware may rewrite the error before it is sent to the client.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl<T> Middleware for Arc<T>

where T: Middleware + ?Sized,

fn on_request( &self, ctx: &McpContext, request: &JsonRpcRequest, ) -> McpResult<MiddlewareDecision>

fn on_response( &self, ctx: &McpContext, request: &JsonRpcRequest, response: Value, ) -> McpResult<Value>

fn on_error( &self, ctx: &McpContext, request: &JsonRpcRequest, error: McpError, ) -> McpError

Implementors

impl Middleware for RateLimitingMiddleware

impl Middleware for ResponseCachingMiddleware

impl Middleware for SlidingWindowRateLimitingMiddleware