/*
 * Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
 *
 * 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 org.springframework.security.web;

import org.springframework.security.core.AuthenticationException;
import org.springframework.security.web.access.ExceptionTranslationFilter;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Used by {@link ExceptionTranslationFilter} to commence an authentication scheme.
 *
 * @author Ben Alex
 */
public interface AuthenticationEntryPoint {
	// ~ Methods
	// ========================================================================================================

	/**
	 * Commences an authentication scheme.
	 * <p>
	 * <code>ExceptionTranslationFilter</code> will populate the <code>HttpSession</code>
	 * attribute named
	 * <code>AbstractAuthenticationProcessingFilter.SPRING_SECURITY_SAVED_REQUEST_KEY</code>
	 * with the requested target URL before calling this method.
	 * <p>
	 * Implementations should modify the headers on the <code>ServletResponse</code> as
	 * necessary to commence the authentication process.
	 *
	 * @param request that resulted in an <code>AuthenticationException</code>
	 * @param response so that the user agent can begin authentication
	 * @param authException that caused the invocation
	 *
	 */
	void commence(HttpServletRequest request, HttpServletResponse response,
			AuthenticationException authException) throws IOException, ServletException;
}
