com.lightbend.lagom.javadsl.server

Interface HeaderServiceCall<Request,Response>

All Superinterfaces:

ServerServiceCall<Request,Response>, ServiceCall<Request,Response>

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface HeaderServiceCall<Request,Response>
extends ServerServiceCall<Request,Response>

A service call that can handle headers.

This exists as a convenience functional interface for implementing service calls that handle the request and response headers. It is intended for use in two ways, one is by changing the return type of the server implementation of a service call to be this more specific type, allowing the service call to be implemented as a lambda. The other way is to invoke the of(HeaderServiceCall) method.

Generally, you shouldn't need to implement this interface with anything but a lambda.

Method Summary

Modifier and Type	Method and Description
static <Request,Response> HeaderServiceCall<Request,Response>	compose(Function<RequestHeader,? extends ServerServiceCall<Request,Response>> block) Compose a header service call.
static <Request,Response> HeaderServiceCall<Request,Response>	composeAsync(Function<RequestHeader,CompletionStage<? extends ServerServiceCall<Request,Response>>> block) Compose a header service call asynchronously.
default CompletionStage<Response>	invoke(Request request) Invoke the service call.
CompletionStage<akka.japi.Pair<ResponseHeader,Response>>	invokeWithHeaders(RequestHeader requestHeader, Request request) Invoke the given action with the request and response headers.
static <Request,Response> HeaderServiceCall<Request,Response>	of(HeaderServiceCall<Request,Response> serviceCall) Convenience method for providing a HeaderServiceCall when a method accepts a less specific type, eg ServerServiceCall.

Methods inherited from interface com.lightbend.lagom.javadsl.server.ServerServiceCall

handleRequestHeader, handleResponseHeader

Methods inherited from interface com.lightbend.lagom.javadsl.api.ServiceCall

invoke, withResponseHeader

Method Detail

invokeWithHeaders

CompletionStage<akka.japi.Pair<ResponseHeader,Response>> invokeWithHeaders(RequestHeader requestHeader,
                                                                           Request request)

Invoke the given action with the request and response headers.

This is overridden from ServerServiceCall.invokeWithHeaders(RequestHeader, Object) to allow it to be made an abstract method.

Specified by:

invokeWithHeaders in interface ServerServiceCall<Request,Response>

Parameters:

requestHeader - The request header.

request - The request message.

Returns:

A future of the response header and response message.

invoke

default CompletionStage<Response> invoke(Request request)

Description copied from interface: ServiceCall

Invoke the service call.

Specified by:

invoke in interface ServiceCall<Request,Response>

Parameters:

request - The request entity.

Returns:

A future of the response entity.

of

static <Request,Response> HeaderServiceCall<Request,Response> of(HeaderServiceCall<Request,Response> serviceCall)

Convenience method for providing a HeaderServiceCall when a method accepts a less specific type, eg ServerServiceCall. For example, the following method:

 <Request, Response> ServerServiceCall<Request, Response> authenticated(
   Function<User, ServerServiceCall<Request, Response>> serviceCall
 );
 

Could be invoked like this:

 authenticated(user -> HeaderServiceCall.of( (requestHeader, request) -> {
     ...
 }));
 

Parameters:

serviceCall - The service call.

compose

static <Request,Response> HeaderServiceCall<Request,Response> compose(Function<RequestHeader,? extends ServerServiceCall<Request,Response>> block)

Compose a header service call.

This is useful for implementing service call composition. For example:

 <Request, Response> ServerServiceCall<Request, Response> authenticated(
     Function<String, ServerServiceCall<Request, Response>> block) {

     return HeaderServiceCall.compose(requestHeader -> {

         // Get the user
         String user = requestHeader.principal().orElseGet(() -> {
             throw new NotAuthenticated("Not authenticated");
         }).getName();

         // Pass it to the block, and return the resulting call
         return block.apply(user);
     });
 }
 

Parameters:

block - The block that will do the composition.

Returns:

A header service call.

composeAsync

static <Request,Response> HeaderServiceCall<Request,Response> composeAsync(Function<RequestHeader,CompletionStage<? extends ServerServiceCall<Request,Response>>> block)

Compose a header service call asynchronously.

This is useful for implementing service call composition. For example:

 <Request, Response> ServerServiceCall<Request, Response> authenticated(
     Function<String, ServerServiceCall<Request, Response>> block) {

     return HeaderServiceCall.composeAsync(requestHeader -> {

         // Get the user
         String userName = requestHeader.principal().orElseGet(() -> {
             throw new NotAuthenticated("Not authenticated");
         }).getName();

         // Load the user
         CompletionStage<User> userFuture = userService.getUser(userName);

         // Pass it to the block, and return the resulting call
         return userFuture.thenApply(user -> block.apply(user));
     });
 }
 

Parameters:

block - The block that will do the composition.

Returns:

A header service call.