001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027
028package org.apache.http.nio.protocol;
029
030import java.io.Closeable;
031import java.io.IOException;
032
033import org.apache.http.HttpResponse;
034import org.apache.http.nio.ContentEncoder;
035import org.apache.http.nio.IOControl;
036import org.apache.http.protocol.HttpContext;
037
038/**
039 * {@code HttpAsyncResponseProducer} is a callback interface whose methods
040 * get invoked to generate an HTTP response message and to stream message
041 * content to a non-blocking HTTP connection on the server side.
042 *
043 * @since 4.2
044 */
045public interface HttpAsyncResponseProducer extends Closeable {
046
047    /**
048     * Invoked to generate a HTTP response message head.
049     *
050     * @return HTTP response message.
051     */
052    HttpResponse generateResponse();
053
054    /**
055     * Invoked to write out a chunk of content to the {@link ContentEncoder}.
056     * The {@link IOControl} interface can be used to suspend output event
057     * notifications if the producer is temporarily unable to produce more content.
058     * <p>
059     * When all content is finished, the producer <b>MUST</b> call
060     * {@link ContentEncoder#complete()}. Failure to do so may cause the entity
061     * to be incorrectly delimited.
062     * <p>
063     * Please note that the {@link ContentEncoder} object is not thread-safe and
064     * should only be used within the context of this method call.
065     * The {@link IOControl} object can be shared and used on other thread
066     * to resume output event notifications when more content is made available.
067     *
068     * @param encoder content encoder.
069     * @param ioctrl I/O control of the underlying connection.
070     * @throws IOException in case of an I/O error
071     */
072    void produceContent(ContentEncoder encoder, IOControl ioctrl) throws IOException;
073
074    /**
075     * Invoked to signal that the response has been fully written out.
076     *
077     * @param context HTTP context
078     */
079    void responseCompleted(HttpContext context);
080
081    /**
082     * Invoked to signal that the response processing terminated abnormally.
083     *
084     * @param ex exception
085     */
086    void failed(Exception ex);
087
088}