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1   /*
2   * Copyright 2004 The Apache Software Foundation
3   *
4   * Licensed under the Apache License, Version 2.0 (the "License");
5   * you may not use this file except in compliance with the License.
6   * You may obtain a copy of the License at
7   *
8   *     http://www.apache.org/licenses/LICENSE-2.0
9   *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16  package javax.servlet;
17  
18  /**
19   * Ensures that servlets handle
20   * only one request at a time. This interface has no methods.
21   *
22   * <p>If a servlet implements this interface, you are <i>guaranteed</i>
23   * that no two threads will execute concurrently in the
24   * servlet's <code>service</code> method. The servlet container
25   * can make this guarantee by synchronizing access to a single
26   * instance of the servlet, or by maintaining a pool of servlet
27   * instances and dispatching each new request to a free servlet.
28   *
29   * <p>Note that SingleThreadModel does not solve all thread safety
30   * issues.  For example, session attributes and static variables can
31   * still be accessed by multiple requests on multiple threads
32   * at the same time, even when SingleThreadModel servlets are used.
33   * It is recommended that a developer take other means to resolve
34   * those issues instead of implementing this interface, such as
35   * avoiding the usage of an instance variable or synchronizing
36   * the block of the code accessing those resources.
37   * This interface is deprecated in Servlet API version 2.4.
38   *
39   *
40   * @author	Various
41   * @version	$Version$
42   *
43   * @deprecated	As of Java Servlet API 2.4, with no direct
44   *	replacement.
45   */
46  
47  public interface SingleThreadModel {
48  }