ratpack.stream.StreamMapper Maven / Gradle / Ivy
/*
* Copyright 2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package ratpack.stream;
import org.reactivestreams.Publisher;
import org.reactivestreams.Subscription;
/**
* Fundamentally transforms a stream.
*
* @param the type of item emitted from upstream
* @param the type of item to emit downstream (i.e. post transform)
* @since 1.4
* @see Streams#streamMap(Publisher, StreamMapper)
*/
public interface StreamMapper {
/**
* A transform step in a {@link Publisher} chain.
*
* @param subscription the upstream subscription
* @param downstream the downstream to write to
* @return a write stream that receives signals from upstream
* @throws Exception any error in establishing the mapping
*/
WriteStream map(Subscription subscription, WriteStream downstream) throws Exception;
}