/*
 * Copyright (c) OSGi Alliance (2000, 2013). All Rights Reserved.
 *
 * 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.osgi.service.http;

import java.util.Dictionary;
import javax.servlet.Servlet;
import javax.servlet.ServletException;

/**
 * The Http Service allows other bundles in the OSGi environment to dynamically
 * register resources and servlets into the URI namespace of Http Service. A
 * bundle may later unregister its resources or servlets.
 * 
 * @noimplement
 * @author $Id: c7dcd5824096b8a0d98ffe6a0b7b9de336e864f6 $
 * @see HttpContext
 */
public interface HttpService {
	/**
	 * Registers a servlet into the URI namespace.
	 * 
	 * <p>
	 * The alias is the name in the URI namespace of the Http Service at which
	 * the registration will be mapped.
	 * 
	 * <p>
	 * An alias must begin with slash ('/') and must not end with slash ('/'),
	 * with the exception that an alias of the form &quot;/&quot; is used to
	 * denote the root alias. See the specification text for details on how HTTP
	 * requests are mapped to servlet and resource registrations.
	 * 
	 * <p>
	 * The Http Service will call the servlet's {@code init} method before
	 * returning.
	 * 
	 * <pre>
	 * httpService.registerServlet(&quot;/myservlet&quot;, servlet, initparams, context);
	 * </pre>
	 * 
	 * <p>
	 * Servlets registered with the same {@code HttpContext} object will share
	 * the same {@code ServletContext}. The Http Service will call the
	 * {@code context} argument to support the {@code ServletContext} methods
	 * {@code getResource},{@code getResourceAsStream} and {@code getMimeType},
	 * and to handle security for requests. If the {@code context} argument is
	 * {@code null}, a default {@code HttpContext} object is used (see
	 * {@link #createDefaultHttpContext()}).
	 * 
	 * @param alias name in the URI namespace at which the servlet is registered
	 * @param servlet the servlet object to register
	 * @param initparams initialization arguments for the servlet or
	 *        {@code null} if there are none. This argument is used by the
	 *        servlet's {@code ServletConfig} object.
	 * @param context the {@code HttpContext} object for the registered servlet,
	 *        or {@code null} if a default {@code HttpContext} is to be created
	 *        and used.
	 * @throws NamespaceException if the registration fails because the alias is
	 *         already in use.
	 * @throws javax.servlet.ServletException if the servlet's {@code init}
	 *         method throws an exception, or the given servlet object has
	 *         already been registered at a different alias.
	 * @throws java.lang.IllegalArgumentException if any of the arguments are
	 *         invalid
	 */
	public void registerServlet(String alias, Servlet servlet, Dictionary initparams, HttpContext context) throws ServletException, NamespaceException;

	/**
	 * Registers resources into the URI namespace.
	 * 
	 * <p>
	 * The alias is the name in the URI namespace of the Http Service at which
	 * the registration will be mapped. An alias must begin with slash ('/') and
	 * must not end with slash ('/'), with the exception that an alias of the
	 * form &quot;/&quot; is used to denote the root alias. The name parameter
	 * must also not end with slash ('/') with the exception that a name of the
	 * form &quot;/&quot; is used to denote the root of the bundle. See the
	 * specification text for details on how HTTP requests are mapped to servlet
	 * and resource registrations.
	 * <p>
	 * For example, suppose the resource name /tmp is registered to the alias
	 * /files. A request for /files/foo.txt will map to the resource name
	 * /tmp/foo.txt.
	 * 
	 * <pre>
	 * httpservice.registerResources(&quot;/files&quot;, &quot;/tmp&quot;, context);
	 * </pre>
	 * 
	 * The Http Service will call the {@code HttpContext} argument to map
	 * resource names to URLs and MIME types and to handle security for
	 * requests. If the {@code HttpContext} argument is {@code null}, a default
	 * {@code HttpContext} is used (see {@link #createDefaultHttpContext()}).
	 * 
	 * @param alias name in the URI namespace at which the resources are
	 *        registered
	 * @param name the base name of the resources that will be registered
	 * @param context the {@code HttpContext} object for the registered
	 *        resources, or {@code null} if a default {@code HttpContext} is to
	 *        be created and used.
	 * @throws NamespaceException if the registration fails because the alias is
	 *         already in use.
	 * @throws java.lang.IllegalArgumentException if any of the parameters are
	 *         invalid
	 */
	public void registerResources(String alias, String name, HttpContext context) throws NamespaceException;

	/**
	 * Unregisters a previous registration done by {@code registerServlet} or
	 * {@code registerResources} methods.
	 * 
	 * <p>
	 * After this call, the registered alias in the URI name-space will no
	 * longer be available. If the registration was for a servlet, the Http
	 * Service must call the {@code destroy} method of the servlet before
	 * returning.
	 * <p>
	 * If the bundle which performed the registration is stopped or otherwise
	 * "unget"s the Http Service without calling {@link #unregister(String)}
	 * then Http Service must automatically unregister the registration.
	 * However, if the registration was for a servlet, the {@code destroy}
	 * method of the servlet will not be called in this case since the bundle
	 * may be stopped. {@link #unregister(String)} must be explicitly called to
	 * cause the {@code destroy} method of the servlet to be called. This can be
	 * done in the {@code BundleActivator.stop} method of the bundle registering
	 * the servlet.
	 * 
	 * @param alias name in the URI name-space of the registration to unregister
	 * @throws java.lang.IllegalArgumentException if there is no registration
	 *         for the alias or the calling bundle was not the bundle which
	 *         registered the alias.
	 */
	public void unregister(String alias);

	/**
	 * Creates a default {@code HttpContext} for registering servlets or
	 * resources with the HttpService, a new {@code HttpContext} object is
	 * created each time this method is called.
	 * 
	 * <p>
	 * The behavior of the methods on the default {@code HttpContext} is defined
	 * as follows:
	 * <ul>
	 * <li>{@code getMimeType} - Does not define any customized MIME types for
	 * the Content-Type header in the response, and always returns {@code null}.
	 * </li>
	 * <li>{@code handleSecurity} - Performs implementation-defined
	 * authentication on the request.</li>
	 * <li>{@code getResource} - Assumes the named resource is in the context
	 * bundle; this method calls the context bundle's {@code Bundle.getResource}
	 * method, and returns the appropriate URL to access the resource. On a Java
	 * runtime environment that supports permissions, the Http Service needs to
	 * be granted {@code org.osgi.framework.AdminPermission[*,RESOURCE]}.</li>
	 * </ul>
	 * 
	 * @return a default {@code HttpContext} object.
	 * @since 1.1
	 */
	public HttpContext createDefaultHttpContext();
}
