Added code contributed by BJ Hargrave to begin a Servlet 2.1 API bundle (FELIX-40).
git-svn-id: https://svn.apache.org/repos/asf/incubator/felix/trunk@355208 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/javax.servlet/src/main/java/javax/servlet/Servlet.java b/javax.servlet/src/main/java/javax/servlet/Servlet.java
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+/*
+ * Copyright 1999,2005 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.
+ */
+
+package javax.servlet;
+
+import java.io.IOException;
+
+
+/**
+ * Defines methods that all servlets must implement.
+ *
+ * <p>A servlet is a small Java program that runs within a Web server.
+ * Servlets receive and respond to requests from Web clients,
+ * usually across HTTP, the HyperText Transfer Protocol.
+ *
+ * <p>To implement this interface, you can write a generic servlet
+ * that extends
+ * <code>javax.servlet.GenericServlet</code> or an HTTP servlet that
+ * extends <code>javax.servlet.http.HttpServlet</code>.
+ *
+ * <p>This interface defines methods to initialize a servlet,
+ * to service requests, and to remove a servlet from the server.
+ * These are known as life-cycle methods and are called in the
+ * following sequence:
+ * <ol>
+ * <li>The servlet is constructed, then initialized with the <code>init</code> method.
+ * <li>Any calls from clients to the <code>service</code> method are handled.
+ * <li>The servlet is taken out of service, then destroyed with the
+ * <code>destroy</code> method, then garbage collected and finalized.
+ * </ol>
+ *
+ * <p>In addition to the life-cycle methods, this interface
+ * provides the <code>getServletConfig</code> method, which the servlet
+ * can use to get any startup information, and the <code>getServletInfo</code>
+ * method, which allows the servlet to return basic information about itself,
+ * such as author, version, and copyright.
+ *
+ * @author Various
+ * @version $Version$
+ *
+ * @see GenericServlet
+ * @see javax.servlet.http.HttpServlet
+ *
+ */
+
+
+public interface Servlet {
+
+ /**
+ * Called by the servlet container to indicate to a servlet that the
+ * servlet is being placed into service.
+ *
+ * <p>The servlet container calls the <code>init</code>
+ * method exactly once after instantiating the servlet.
+ * The <code>init</code> method must complete successfully
+ * before the servlet can receive any requests.
+ *
+ * <p>The servlet container cannot place the servlet into service
+ * if the <code>init</code> method
+ * <ol>
+ * <li>Throws a <code>ServletException</code>
+ * <li>Does not return within a time period defined by the Web server
+ * </ol>
+ *
+ *
+ * @param config a <code>ServletConfig</code> object
+ * containing the servlet's
+ * configuration and initialization parameters
+ *
+ * @exception ServletException if an exception has occurred that
+ * interferes with the servlet's normal
+ * operation
+ *
+ * @see UnavailableException
+ * @see #getServletConfig
+ *
+ */
+
+ public void init(ServletConfig config) throws ServletException;
+
+
+
+ /**
+ *
+ * Returns a {@link ServletConfig} object, which contains
+ * initialization and startup parameters for this servlet.
+ * The <code>ServletConfig</code> object returned is the one
+ * passed to the <code>init</code> method.
+ *
+ * <p>Implementations of this interface are responsible for storing the
+ * <code>ServletConfig</code> object so that this
+ * method can return it. The {@link GenericServlet}
+ * class, which implements this interface, already does this.
+ *
+ * @return the <code>ServletConfig</code> object
+ * that initializes this servlet
+ *
+ * @see #init
+ *
+ */
+
+ public ServletConfig getServletConfig();
+
+
+
+ /**
+ * Called by the servlet container to allow the servlet to respond to
+ * a request.
+ *
+ * <p>This method is only called after the servlet's <code>init()</code>
+ * method has completed successfully.
+ *
+ * <p> The status code of the response always should be set for a servlet
+ * that throws or sends an error.
+ *
+ *
+ * <p>Servlets typically run inside multithreaded servlet containers
+ * that can handle multiple requests concurrently. Developers must
+ * be aware to synchronize access to any shared resources such as files,
+ * network connections, and as well as the servlet's class and instance
+ * variables.
+ * More information on multithreaded programming in Java is available in
+ * <a href="http://java.sun.com/Series/Tutorial/java/threads/multithreaded.html">
+ * the Java tutorial on multi-threaded programming</a>.
+ *
+ *
+ * @param req the <code>ServletRequest</code> object that contains
+ * the client's request
+ *
+ * @param res the <code>ServletResponse</code> object that contains
+ * the servlet's response
+ *
+ * @exception ServletException if an exception occurs that interferes
+ * with the servlet's normal operation
+ *
+ * @exception IOException if an input or output exception occurs
+ *
+ */
+
+ public void service(ServletRequest req, ServletResponse res)
+ throws ServletException, IOException;
+
+
+
+ /**
+ * Returns information about the servlet, such
+ * as author, version, and copyright.
+ *
+ * <p>The string that this method returns should
+ * be plain text and not markup of any kind (such as HTML, XML,
+ * etc.).
+ *
+ * @return a <code>String</code> containing servlet information
+ *
+ */
+
+ public String getServletInfo();
+
+
+
+ /**
+ *
+ * Called by the servlet container to indicate to a servlet that the
+ * servlet is being taken out of service. This method is
+ * only called once all threads within the servlet's
+ * <code>service</code> method have exited or after a timeout
+ * period has passed. After the servlet container calls this
+ * method, it will not call the <code>service</code> method again
+ * on this servlet.
+ *
+ * <p>This method gives the servlet an opportunity
+ * to clean up any resources that are being held (for example, memory,
+ * file handles, threads) and make sure that any persistent state is
+ * synchronized with the servlet's current state in memory.
+ *
+ */
+
+ public void destroy();
+}