001/*
002 * The contents of this file are subject to the terms of the Common Development and
003 * Distribution License (the License). You may not use this file except in compliance with the
004 * License.
005 *
006 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
007 * specific language governing permission and limitations under the License.
008 *
009 * When distributing Covered Software, include this CDDL Header Notice in each file and include
010 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
011 * Header, with the fields enclosed by brackets [] replaced by your own identifying
012 * information: "Portions Copyright [year] [name of copyright owner]".
013 *
014 * Copyright 2010–2011 ApexIdentity Inc.
015 * Portions Copyright 2011-2014 ForgeRock AS.
016 */
017
018package org.forgerock.openig.filter;
019
020import java.io.IOException;
021
022import org.forgerock.openig.handler.Handler;
023import org.forgerock.openig.handler.HandlerException;
024import org.forgerock.openig.http.Exchange;
025
026/**
027 * Filters the request and/or response of an HTTP exchange.
028 *
029 * @see Chain
030 */
031public interface Filter {
032
033    /**
034     * Filters the request and/or response of an exchange. Initially, {@code exchange.request}
035     * contains the request to be filtered. To pass the request to the next filter or handler
036     * in the chain, the filter calls {@code next.handle(exchange)}. After this call,
037     * {@code exchange.response} contains the response that can be filtered.
038     * <p>
039     * This method may elect not to pass the request to the next filter or handler, and instead
040     * handle the request itself. It can achieve this by merely avoiding a call to
041     * {@code next.handle(exchange)} and creating its own response object the exchange. The
042     * filter is also at liberty to replace a response with another of its own after the call
043     * to {@code next.handle(exchange)}.
044     * <p>
045     * <strong>Important note:</strong> If an existing response exists in the exchange object
046     * and the filter intends to replace it with its own, it must first check to see if the
047     * existing response has an entity, and if it does, must call its {@code close} method in
048     * order to signal that the processing of the response from a remote server is complete.
049     *
050     * @param exchange the exchange containing the request and response to filter.
051     * @param next the next filter or handler in the chain to handle the exchange.
052     * @throws HandlerException if an exception occurred handling the exchange.
053     * @throws IOException if an I/O exception occurred.
054     */
055    void filter(Exchange exchange, Handler next) throws HandlerException, IOException;
056}