271 lines
9.9 KiB
XML
271 lines
9.9 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!--
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<!DOCTYPE document [
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<!ENTITY project SYSTEM "project.xml">
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]>
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<document url="fs-default.html">
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&project;
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<properties>
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<author email="craigmcc@apache.org">Craig McClanahan</author>
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<title>Default Servlet</title>
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</properties>
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<body>
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<section name="Table of Contents">
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<toc/>
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</section>
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<section name="Overview">
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<subsection name="Introduction">
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<p>The purpose of the <strong>Default Servlet</strong> is to serve
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static resources of a web application in response to client requests.
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As the name implies, it is generally configured as the "default"
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servlet for a web application, by being mapped to a URL pattern "/".</p>
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</subsection>
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<subsection name="External Specifications">
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<p>The following external specifications have provisions which
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partially define the correct behavior of the default servlet:</p>
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<ul>
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<li><a href="https://jcp.org/aboutJava/communityprocess/final/jsr340/index.html">
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Servlet Specification</a> (Version 3.1)</li>
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<li><a href="https://www.rfc-editor.org/rfc/rfc2046.txt">Multipurpose
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Internet Mail Extensions (MIME) Part Two: Media Types</a></li>
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<li><a href="https://www.rfc-editor.org/rfc/rfc2616.txt">Hypertext
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Transfer Protocol – HTTP/1.1</a></li>
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</ul>
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</subsection>
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<subsection name="Implementation Requirements">
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<p>The implementation of this functionality shall conform to the
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following requirements:</p>
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<ul>
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<li>Must be implemented as a servlet.</li>
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<li>Must support configurable parameters for debugging detail level,
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input buffer size, output buffer size, whether or not to produce
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directory listings when no welcome file is present, and whether or not
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modifications are supported via DELETE and PUT.</li>
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<li>Log debugging and operational messages (suitably internationalized)
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via the <code>getServletContext().log()</code> method.</li>
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</ul>
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</subsection>
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</section>
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<section name="Dependencies">
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<subsection name="Environmental Dependencies">
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<p>The following environmental dependencies must be met in order for
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the default servlet to operate correctly:</p>
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<ul>
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<li>The default servlet must be registered in the application deployment
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descriptor (or the default deployment descriptor in file
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<code>$CATALINA_BASE/conf/web.xml</code>) using a "default servlet"
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servlet mapping, signified by URL pattern "/".</li>
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</ul>
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</subsection>
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<subsection name="Container Dependencies">
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<p>Correct operation of the default servlet depends on the following
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specific features of the surrounding container:</p>
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<ul>
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<li>The container shall provide a servlet context attribute that
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lists the welcome file names that have been defined for this
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web application.</li>
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<li>The container shall provide a servlet context attribute that
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contains a <code>javax.naming.directory.DirContext</code>
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implementation representing the static resources of this
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web application.</li>
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</ul>
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</subsection>
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</section>
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<section name="Functionality">
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<subsection name="Initialization Functionality">
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<p>The following processing must be performed when the <code>init()</code>
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method of the default servlet is called:</p>
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<ul>
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<li>Process and sanity check configuration parameters.</li>
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</ul>
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</subsection>
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<subsection name="Per-Request Functionality">
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<p>For all HTTP request methods, the resource path is determined from
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the path information provided to this request, either as request attribute
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<code>javax.servlet.include.path_info</code> (for a request dispatcher
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access to a static resource) or by calling
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<code>request.getPathInfo()</code> directly.</p>
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<p>On each HTTP DELETE request processed by this servlet, the following
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processing shall be performed:</p>
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<ul>
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<li>If modifications to the static resources are not allowed (set by a
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configuration parameter), return HTTP status 403 (forbidden).</li>
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<li>If an attempt is made to delete a resource from <code>/META-INF</code>
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or <code>/WEB-INF</code>, return HTTP status 403 (forbidden).</li>
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<li>If the requested resource does not exist, return HTTP status 404
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(not found)</li>
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<li>Unbind the resource from the directory context containing the
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static resources for this web application. If successful, return
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HTTP status 204 (no content). Otherwise, return HTTP status 405
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(method not allowed).</li>
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</ul>
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<p>On each HTTP GET request processed by this servlet, the following
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processing shall be performed:</p>
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<ul>
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<li>If the request is for a resource under <code>/META-INF</code> or
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<code>/WEB-INF</code>, return HTTP status 404 (not found).</li>
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<li>If the requested resource does not exist, return HTTP status 404
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(not found).</li>
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<li>If the requested resource is not a directory, but the resource
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path ends in "/" or "\", return HTTP status 404 (not found).</li>
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<li>If the requested resource is a directory:
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<ul>
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<li>If the request path does not end with "/", redirect to a
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corresponding path with "/" appended so that relative references
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in welcome files are resolved correctly.</li>
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<li>If one of the specified welcome files exists, redirect to the
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path for that welcome file so that it will be served explicitly.
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</li>
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</ul></li>
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<li>If the request being processed contains an <code>If-Range</code>
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header, perform the processing described in the HTTP/1.1 specification
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to determine whether the client's information is up to date.</li>
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<li>Determine the content type of the response, by looking up the
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corresponding MIME type in our servlet context.</li>
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<li>If the requested resource is a directory:
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<ul>
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<li>If directory listings are suppressed, return HTTP status 404
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(not found).</li>
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<li>Set the content type to <code>text/html</code>.</li>
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</ul></li>
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<li>Determine the range(s) to be returned, based on the existence of
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any <code>If-Range</code> and <code>Range</code> headers.</li>
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<li>If the requested resource is a directory, include an <code>ETag</code>
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header in the response, with the value calculated based on the content
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of the directory.</li>
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<li>Include a <code>Last-Modified</code> header in the response documenting
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the date/time that the resource was last modified.</li>
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<li>Unless we are processing a HEAD request, include the appropriate
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content (or content ranges) in the response.</li>
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</ul>
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<p>On each HTTP HEAD request processed by this servlet, the following
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processing shall be performed:</p>
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<ul>
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<li>Processed identically to an HTTP GET request, except that the data
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content is not transmitted after the headers.</li>
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</ul>
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<p>On each HTTP POST request processed by this servlet, the following
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processing shall be performed:</p>
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<ul>
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<li>Processed identically to an HTTP GET request.</li>
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</ul>
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<p>On each HTTP PUT request processed by this servlet, the following
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processing shall be performed:</p>
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<ul>
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<li>If modifications to the static resources are not allowed (set by a
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configuration parameter), return HTTP status 403 (forbidden).</li>
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<li>If an attempt is made to delete a resource from <code>/META-INF</code>
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or <code>/WEB-INF</code>, return HTTP status 403 (forbidden).</li>
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<li>Create a new resource from the body of this request.</li>
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<li>Bind or rebind the specified path to the new resource (depending on
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whether it currently exists or not). Return HTTP status as follows:
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<ul>
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<li>If binding was unsuccessful, return HTTP status 409 (conflict).
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</li>
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<li>If binding was successful and the resource did not previously
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exist, return HTTP status 201 (created).</li>
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<li>If binding was successful and the resource previously existed,
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return HTTP status 204 (no content).</li>
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</ul></li>
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</ul>
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</subsection>
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<subsection name="Finalization Functionality">
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<p>No specific processing is required when the <code>destroy()</code>
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method is called:</p>
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</subsection>
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</section>
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<section name="Testable Assertions">
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<p>In addition to the assertions implied by the functionality requirements
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listed above, the following additional assertions shall be tested to
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validate the behavior of the default servlet:</p>
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<ul>
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<li>Requests for resources that do not exist in the web application must
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return HTTP status 404 (not found).</li>
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<li>The default servlet must operate identically for web applications that
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are run out of a WAR file directly, or from an unpacked directory
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structure.</li>
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<li>If the web application is running out of an unpacked directory
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structure, the default servlet must recognize cases where the resource
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has been updated through external means.</li>
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</ul>
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</section>
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</body>
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</document>
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