/*
 * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/auth/CredentialsProvider.java,v 1.6 2004/07/05 22:46:59 olegk Exp $
 * $Revision: 1.6 $
 * $Date: 2004/07/05 22:46:59 $
 *
 * ====================================================================
 *
 *  Copyright 2002-2004 The Apache Software Foundation
 *
 *  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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient.auth;

import org.apache.commons.httpclient.Credentials;

/**
 * <p>
 * Credentials provider interface can be used to provide {@link 
 * org.apache.commons.httpclient.HttpMethod HTTP method} with a means 
 * to request authentication credentials if no credentials have been given 
 * or given credentials are incorrect. 
 * </p>
 * 
 * Classes implementing this interface must synchronize access to shared
 * data as methods of this interfrace may be executed from multiple threads 
 * 
 * @author Ortwin Glueck
 * @author <a href="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
 * 
 * @since 3.0
 */
public interface CredentialsProvider {

    /**
     * Sets the credentials provider parameter.
     * <p>
     * This parameter expects a value of type {@link CredentialsProvider}.
     * </p>
     */ 
    public static final String PROVIDER = "http.authentication.credential-provider";
    
    /**
     * Requests additional {@link Credentials authentication credentials}.
     * 
     * @param scheme the {@link AuthScheme authentication scheme}
     * @param host the authentication host
     * @param port the port of the authentication host
     * @param proxy <tt>true</tt> if authenticating with a proxy,
     *              <tt>false</tt> otherwise
     */ 
    public Credentials getCredentials(
        final AuthScheme scheme, 
        final String host, 
        int port, 
        boolean proxy) throws CredentialsNotAvailableException; 

}