[][src]Trait actix_web::dev::Service

pub trait Service where
    <Self::Future as Future>::Output == Result<Self::Response, Self::Error>, 
{ type Request; type Response; type Error; type Future: Future; fn poll_ready(&mut self, ctx: &mut Context) -> Poll<Result<(), Self::Error>>;
fn call(&mut self, req: Self::Request) -> Self::Future; fn map<F, R>(self, f: F) -> Map<Self, F, R>
    where
        F: FnMut(Self::Response) -> R
, { ... }
fn map_err<F, E>(self, f: F) -> MapErr<Self, F, E>
    where
        F: Fn(Self::Error) -> E
, { ... } }

An asynchronous function from Request to a Response.

Service represents a service that represanting interation, taking requests and giving back replies. You can think about service as a function with one argument and result as a return type. In general form it looks like async fn(Req) -> Result<Res, Err>. Service trait just generalizing form of this function. Each parameter described as an assotiated type.

Services provides a symmetric and uniform API, same abstractions represents clients and servers. Services describe only transforamtion operation which encorouge to simplify api surface and phrases value transformation. That leads to simplier design of each service. That also allows better testability and better composition.

Services could be represented in several different forms. In general, Service is a type that implements Service trait.

This example is not tested
struct MyService;

impl Service for MyService {
     type Request = u8;
     type Response = u64;
     type Error = MyError;
     type Future = Pin<Box<Future<Output=Result<Self::Response, Self::Error>>>;

     fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { ... }

     fn call(&mut self, req: Self::Request) -> Self::Future { ... }
}

Service can have mutable state that influence computation. This service could be rewritten as a simple function:

This example is not tested
async fn my_service(req: u8) -> Result<u64, MyError>;

Associated Types

type Request

Requests handled by the service.

type Response

Responses given by the service.

type Error

Errors produced by the service.

type Future: Future

The future response value.

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Required methods

fn poll_ready(&mut self, ctx: &mut Context) -> Poll<Result<(), Self::Error>>

Returns Ready when the service is able to process requests.

If the service is at capacity, then Pending is returned and the task is notified when the service becomes ready again. This function is expected to be called while on a task.

This is a best effort implementation. False positives are permitted. It is permitted for the service to return Ready from a poll_ready call and the next invocation of call results in an error.

There are several notes to consider:

  1. .poll_ready() might be called on different task from actual service call.

  2. In case of chained services, .poll_ready() get called for all services at once.

fn call(&mut self, req: Self::Request) -> Self::Future

Process the request and return the response asynchronously.

This function is expected to be callable off task. As such, implementations should take care to not call poll_ready. If the service is at capacity and the request is unable to be handled, the returned Future should resolve to an error.

Calling call without calling poll_ready is permitted. The implementation must be resilient to this fact.

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Provided methods

fn map<F, R>(self, f: F) -> Map<Self, F, R> where
    F: FnMut(Self::Response) -> R, 

Map this service's output to a different type, returning a new service of the resulting type.

This function is similar to the Option::map or Iterator::map where it will change the type of the underlying service.

Note that this function consumes the receiving service and returns a wrapped version of it, similar to the existing map methods in the standard library.

fn map_err<F, E>(self, f: F) -> MapErr<Self, F, E> where
    F: Fn(Self::Error) -> E, 

Map this service's error to a different error, returning a new service.

This function is similar to the Result::map_err where it will change the error type of the underlying service. This is useful for example to ensure that services have the same error type.

Note that this function consumes the receiving service and returns a wrapped version of it.

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Implementations on Foreign Types

impl<T> Service for UpgradeHandler<T>[src]

type Request = (Request<Pin<Box<dyn Stream<Item = Result<Bytes, PayloadError>> + 'static>>>, Framed<T, Codec>)

type Response = ()

type Error = Error

type Future = Ready<Result<<UpgradeHandler<T> as Service>::Response, <UpgradeHandler<T> as Service>::Error>>

impl Service for ExpectHandler[src]

type Request = Request<Pin<Box<dyn Stream<Item = Result<Bytes, PayloadError>> + 'static>>>

type Response = Request<Pin<Box<dyn Stream<Item = Result<Bytes, PayloadError>> + 'static>>>

type Error = Error

type Future = Ready<Result<<ExpectHandler as Service>::Response, <ExpectHandler as Service>::Error>>

impl<T, S, B, X, U> Service for H1ServiceHandler<T, S, B, X, U> where
    B: MessageBody,
    S: Service<Request = Request<Pin<Box<dyn Stream<Item = Result<Bytes, PayloadError>> + 'static>>>>,
    T: AsyncRead + AsyncWrite + Unpin,
    U: Service<Request = (Request<Pin<Box<dyn Stream<Item = Result<Bytes, PayloadError>> + 'static>>>, Framed<T, Codec>), Response = ()>,
    X: Service<Request = Request<Pin<Box<dyn Stream<Item = Result<Bytes, PayloadError>> + 'static>>>, Response = Request<Pin<Box<dyn Stream<Item = Result<Bytes, PayloadError>> + 'static>>>>,
    <S as Service>::Error: Into<Error>,
    <S as Service>::Response: Into<Response<B>>,
    <X as Service>::Error: Into<Error>,
    <U as Service>::Error: Display,
    <U as Service>::Error: Into<Error>, 
[src]

type Request = (T, Option<SocketAddr>)

type Response = ()

type Error = DispatchError

type Future = Dispatcher<T, S, B, X, U>

impl<S> Service for Box<S> where
    S: Service + ?Sized
[src]

type Request = <S as Service>::Request

type Response = <S as Service>::Response

type Error = <S as Service>::Error

type Future = <S as Service>::Future

impl<T> Service for Pipeline<T> where
    T: Service
[src]

type Request = <T as Service>::Request

type Response = <T as Service>::Response

type Error = <T as Service>::Error

type Future = <T as Service>::Future

impl<A, F, Response> Service for Map<A, F, Response> where
    A: Service,
    F: FnMut(<A as Service>::Response) -> Response + Clone
[src]

type Request = <A as Service>::Request

type Response = Response

type Error = <A as Service>::Error

type Future = MapFuture<A, F, Response>

impl<T, F, R, In, Out, Err> Service for Apply<T, F, R, In, Out, Err> where
    F: FnMut(In, &mut T) -> R,
    R: Future<Output = Result<Out, Err>>,
    T: Service<Error = Err>, 
[src]

type Request = In

type Response = Out

type Error = Err

type Future = R

impl<S> Service for RefCell<S> where
    S: Service
[src]

type Request = <S as Service>::Request

type Response = <S as Service>::Response

type Error = <S as Service>::Error

type Future = <S as Service>::Future

impl<F, Fut, Req, Res, Err> Service for FnService<F, Fut, Req, Res, Err> where
    F: FnMut(Req) -> Fut,
    Fut: Future<Output = Result<Res, Err>>, 
[src]

type Request = Req

type Response = Res

type Error = Err

type Future = Fut

impl<F, Fut, Req, Res, Err> Service for FnServiceFactory<F, Fut, Req, Res, Err, ()> where
    F: FnMut(Req) -> Fut + Clone,
    Fut: Future<Output = Result<Res, Err>>, 
[src]

type Request = Req

type Response = Res

type Error = Err

type Future = Fut

impl<'a, S> Service for &'a mut S where
    S: Service + 'a, 
[src]

type Request = <S as Service>::Request

type Response = <S as Service>::Response

type Error = <S as Service>::Error

type Future = <S as Service>::Future

impl<A, F, E> Service for MapErr<A, F, E> where
    A: Service,
    F: Fn(<A as Service>::Error) -> E + Clone
[src]

type Request = <A as Service>::Request

type Response = <A as Service>::Response

type Error = E

type Future = MapErrFuture<A, F, E>

impl<S> Service for Rc<RefCell<S>> where
    S: Service
[src]

type Request = <S as Service>::Request

type Response = <S as Service>::Response

type Error = <S as Service>::Error

type Future = <S as Service>::Future

impl<T, U> Service for RustlsConnectorService<T, U> where
    T: Address,
    U: AsyncRead + AsyncWrite + Unpin + Debug

type Request = Connection<T, U>

type Response = Connection<T, TlsStream<U>>

type Error = Error

type Future = ConnectAsyncExt<T, U>

impl<T> Service for TcpConnectService<T> where
    T: 'static + Address, 

type Request = Connect<T>

type Response = TcpStream

type Error = ConnectError

type Future = TcpConnectServiceResponse<T>

impl<T> Service for OpensslConnectService<T> where
    T: 'static + Address, 

type Request = Connect<T>

type Response = SslStream<TcpStream>

type Error = ConnectError

type Future = OpensslConnectServiceResponse<T>

impl<T> Service for Resolver<T> where
    T: Address, 

type Request = Connect<T>

type Response = Connect<T>

type Error = ConnectError

type Future = Either<Pin<Box<dyn Future<Output = Result<<Resolver<T> as Service>::Response, <Resolver<T> as Service>::Error>> + 'static>>, Ready<Result<Connect<T>, <Resolver<T> as Service>::Error>>>

impl<T> Service for TcpConnector<T> where
    T: Address, 

type Request = Connect<T>

type Response = Connection<T, TcpStream>

type Error = ConnectError

type Future = Either<TcpConnectorResponse<T>, Ready<Result<<TcpConnector<T> as Service>::Response, <TcpConnector<T> as Service>::Error>>>

impl<T, U> Service for OpensslConnectorService<T, U> where
    T: Address + 'static,
    U: AsyncRead + AsyncWrite + Unpin + Debug + 'static, 

type Request = Connection<T, U>

type Response = Connection<T, SslStream<U>>

type Error = Error

type Future = Either<ConnectAsyncExt<T, U>, Ready<Result<<OpensslConnectorService<T, U> as Service>::Response, <OpensslConnectorService<T, U> as Service>::Error>>>

impl<T> Service for ConnectService<T> where
    T: Address, 

type Request = Connect<T>

type Response = Connection<T, TcpStream>

type Error = ConnectError

type Future = ConnectServiceResponse<T>

impl<S> Service for InOrderService<S> where
    S: Service,
    <S as Service>::Response: 'static,
    <S as Service>::Future: 'static,
    <S as Service>::Error: 'static, 
[src]

type Request = <S as Service>::Request

type Response = <S as Service>::Response

type Error = InOrderError<<S as Service>::Error>

type Future = InOrderServiceResponse<S>

impl Service for LowResTimeService[src]

impl<S> Service for TimeoutService<S> where
    S: Service
[src]

type Request = <S as Service>::Request

type Response = <S as Service>::Response

type Error = TimeoutError<<S as Service>::Error>

type Future = TimeoutServiceResponse<S>

impl<R, E, F> Service for KeepAliveService<R, E, F> where
    F: Fn() -> E, 
[src]

type Request = R

type Response = R

type Error = E

type Future = Ready<Result<R, E>>

impl<T> Service for InFlightService<T> where
    T: Service
[src]

type Request = <T as Service>::Request

type Response = <T as Service>::Response

type Error = <T as Service>::Error

type Future = InFlightServiceResponse<T>

impl<A, B> Service for EitherService<A, B> where
    A: Service,
    B: Service<Response = <A as Service>::Response, Error = <A as Service>::Error>, 
[src]

type Request = Either<<A as Service>::Request, <B as Service>::Request>

type Response = <A as Service>::Response

type Error = <A as Service>::Error

type Future = Either<<A as Service>::Future, <B as Service>::Future>

impl<T> Service for AcceptorService<T> where
    T: Unpin + AsyncRead + AsyncWrite
[src]

type Request = T

type Response = TlsStream<T>

type Error = Error

type Future = AcceptorServiceFut<T>

impl<T> Service for AcceptorService<T> where
    T: 'static + Unpin + AsyncRead + AsyncWrite
[src]

type Request = T

type Response = SslStream<T>

type Error = HandshakeError<T>

type Future = AcceptorServiceResponse<T>

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Implementors

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