2003-04-23 20:53:41 -04:00
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<?xml version="1.0" encoding="UTF-8"?>
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2007-01-15 18:11:09 -05:00
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<!--
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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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====================================================================
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-->
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2003-04-23 20:53:41 -04:00
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<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.1//EN" "../dtd/document-v11.dtd">
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<document>
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<header>
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<title>POIFS Use Cases</title>
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<authors>
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<person email="mjohnson@apache.org" name="Marc Johnson" id="MJ"/>
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</authors>
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</header>
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<body>
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<section><title>POIFS Use Cases</title>
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<section><title>Use Case 1: Read existing file system</title>
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<table>
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<tr>
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<td><em>Primary Actor:</em></td>
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<td>POIFS client</td>
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</tr>
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<tr>
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<td><em>Scope:</em></td>
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<td>POIFS</td>
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</tr>
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<tr>
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<td><em>Level:</em></td>
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<td>Summary</td>
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</tr>
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<tr>
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<td><em>Stakeholders and Interests:</em></td>
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<td>
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POIFS client- wants to read content of file
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system<br/>
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POIFS - understands POIFS file system
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</td>
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</tr>
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<tr>
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<td><em>Precondition:</em></td>
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<td>None</td>
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</tr>
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<tr>
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<td><em>Minimal Guarantee:</em></td>
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<td>None</td>
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</tr>
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<tr>
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<td><em>Main Success Guarantee:</em></td>
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<td>
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1. POIFS client requests POIFS to read a POIFS file
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system, providing an
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<code>InputStream</code>
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containing POIFS file system in question.<br/>
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2. POIFS reads from the
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<code>InputStream</code> in
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512 byte blocks.<br/>
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3. POIFS verifies that the first block begins with
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the well known signature
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(
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<code>0xE11AB1A1E011CFD0</code>)<br/>
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4. POIFS reads the Block Allocation Table from the
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first block and, if necessary, from the XBAT
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blocks.<br/>
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5. POIFS obtains the start block of the Property
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Table and reads the Property Table (use case 9,
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read file)<br/>
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6. POIFS reads the individual entries in the Property
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Table<br/>
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7. POIFS obtains the start block of the Small Block
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Allocation Table and reads the Small Block
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Allocation Table (use case 9, read file)<br/>
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8. POIFS obtains the start block of the Small Block
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store from the first entry in the Property Table
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and reads the Small Block Array (use case 9, read
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file)<br/>
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</td>
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</tr>
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<tr>
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<td><em>Extensions:</em></td>
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<td>
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2a. If the last block read is not a 512 byte
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block, the
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<code>InputStream</code> is not that of
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a POIFS file system, and POIFS throws an
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appropriate exception.
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<br/>
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3a. If the signature is incorrect, the
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<code>InputStream</code> is not that of a POIFS
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file system, and POIFS throws an appropriate
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exception.<br/>
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</td>
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</tr>
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</table>
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</section>
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<section><title>Use Case 2: Write file system</title>
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<table>
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<tr>
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<th>Primary Actor:</th>
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<th>POIFS client</th>
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</tr>
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<tr>
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<th>Scope:</th>
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<td>POIFS</td>
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</tr>
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<tr>
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<th>Level:</th>
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<td>Summary</td>
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</tr>
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<tr>
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<th>Stakeholders and Interests:</th>
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<td>
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POIFS client- wants to write file system out.<br/>
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POIFS - knows how to write file system out.
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</td>
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</tr>
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<tr>
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<th>Precondition:</th>
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<td>
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File system has been read (use case 1, read
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existing file system) and subsequently modified
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(use case 4, replace file in file system; use case
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5, delete file from file system; or use case 6,
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write new file to file system; in any
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combination)
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<br/>or<br/>
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File system has been created (use case 3, create
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new file system)
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</td>
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</tr>
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<tr>
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<th>Minimal Guarantee:</th>
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<td>None</td>
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</tr>
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<tr>
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<th>Main Success Guarantee:</th>
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<td>
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1. POIFS client provides an
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<code>OutputStream</code>
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to write the file system to.
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<br/>
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2. POIFS gets the sizes of the Property Table and
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each file in the file system.<br/>
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3. If any files in the file system requires storage
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in a Small Block Array, POIFS creates a Small
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Block Array of sufficient size to hold all of the
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small files.<br/>
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4. POIFS calculates the number of big blocks needed
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to hold all of the large files, the Property
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Table, and, if necessary, the Small Block Array
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and the Small Block Allocation Table.<br/>
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5. POIFS creates a set of big blocks sufficient to
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store the Block Allocation Table<br/>
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6. POIFS creates and writes the header block<br/>
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7. POIFS writes out the XBAT blocks, if needed.<br/>
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8. POIFS writes out the Small Block Array, if
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needed<br/>
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9. POIFS writes out the Small Block Allocation Table,
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if needed<br/>
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10. POIFS writes out the Property Table<br/>
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11. POIFS writes out the large files, if needed<br/>
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12. POIFS closes the <code>OutputStream</code>.
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</td>
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</tr>
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<tr>
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<th>Extensions:</th>
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<td>
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6a. Exceptions writing to the
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<code>OutputStream</code> will be propagated back
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to the POIFS client.
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<br/>
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7a. Exceptions writing to the
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<code>OutputStream</code> will be propagated back
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to the POIFS client.
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<br/>
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8a. Exceptions writing to the
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<code>OutputStream</code> will be propagated back
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to the POIFS client.
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<br/>
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9a. Exceptions writing to the
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<code>OutputStream</code> will be propagated back
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to the POIFS client.
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<br/>
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10a. Exceptions writing to the
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<code>OutputStream</code> will be propagated back
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to the POIFS client.
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<br/>
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11a. Exceptions writing to the
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<code>OutputStream</code> will be propagated back
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to the POIFS client.
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<br/>
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12a. Exceptions closing the
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<code>OutputStream</code> will be propagated back
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to the POIFS client.
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<br/>
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</td>
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</tr>
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</table>
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</section>
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<section><title>Use Case 3: Create new file system</title>
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<table>
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<tr>
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<th>Primary Actor:</th>
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<td>POIFS client</td>
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</tr>
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<tr>
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<th>Scope:</th>
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<td>POIFS</td>
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</tr>
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<tr>
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<th>Level:</th>
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<td>Summary</td>
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</tr>
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<tr>
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<th>Stakeholders and Interests:</th>
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<td>
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POIFS client- wants to create a new file
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system<br/>
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POIFS - knows how to create a new file system
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</td>
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</tr>
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<tr>
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<th>Precondition:</th>
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<td>None</td>
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</tr>
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<tr>
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<th>Minimal Guarantee:</th>
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<td>None</td>
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</tr>
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<tr>
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<th>Main Success Guarantee:</th>
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<td>
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POIFS creates an empty Property Table.
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</td>
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</tr>
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<tr>
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<th>Extensions:</th>
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<td>None</td>
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</tr>
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</table>
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</section>
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<section><title>Use Case 4: Replace file in file system</title>
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<table>
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<tr>
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<td><em>Primary Actor:</em></td>
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<td>POIFS client</td>
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</tr>
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<tr>
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<td><em>Scope:</em></td>
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<td>POIFS</td>
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</tr>
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<tr>
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<td><em>Level:</em></td>
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<td>Summary</td>
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</tr>
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<tr>
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<td><em>Stakeholders and Interests:</em></td>
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<td>
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1. POIFS client- wants to replace an existing file in
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the file system<br/>
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2. POIFS - knows how to manage the file system
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</td>
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</tr>
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<tr>
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<td><em>Precondition:</em></td>
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<td>
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Either
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<br/><br/>
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The file system has been read (use case 1, read
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existing file system) and a file has been
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extracted from the file system (use case 7, read
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existing file from file system)
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<br/><br/>or<br/><br/>
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The file system has been created (use case 3,
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create new file system) and a file has been
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written to the file system (use case 6, write new
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file to file system)
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</td>
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</tr>
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<tr>
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<td><em>Minimal Guarantee:</em></td>
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<td>None</td>
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</tr>
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<tr>
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<td><em>Main Success Guarantee:</em></td>
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<td>
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1. POIFS discards storage of the existing file.<br/>
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2. POIFS updates the existing file's entry in the
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Property Table<br/>
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3. POIFS stores the new file's data
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</td>
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</tr>
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<tr>
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<td><em>Extensions:</em></td>
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<td>
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1a. POIFS throws an exception if the file does not
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exist.
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</td>
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</tr>
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</table>
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</section>
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<section><title>Use Case 5: Delete file from file system</title>
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<table>
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<tr>
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<td><em>Primary Actor:</em></td>
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<td>POIFS client</td>
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</tr>
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<tr>
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<td><em>Scope:</em></td>
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<td>POIFS</td>
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</tr>
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<tr>
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<td><em>Level:</em></td>
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<td>Summary</td>
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</tr>
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<tr>
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<td><em>Stakeholders and Interests:</em></td>
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<td>
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* POIFS client- wants to remove a file from a file
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system<br/>
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* POIFS - knows how to manage the file system
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</td>
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</tr>
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<tr>
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<td><em>Precondition:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
Either<br/><br/>
|
|
|
|
|
The file system has been read (use case 1, read
|
|
|
|
|
existing file system) and a file has been
|
|
|
|
|
extracted from the file system (use case 7, read
|
|
|
|
|
existing file from file system)<br/>
|
|
|
|
|
<br/>
|
|
|
|
|
or<br/>
|
|
|
|
|
<br/>
|
|
|
|
|
The file system has been created (use case 3,
|
|
|
|
|
create new file system) and a file has been
|
|
|
|
|
written to the file system (use case 6, write new
|
|
|
|
|
file to file system)
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Minimal Guarantee:</em></td>
|
|
|
|
|
<td>None</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Main Success Guarantee:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
1. POIFS discards the specified file's storage.<br/>
|
|
|
|
|
2. POIFS discards the file's Property Table
|
|
|
|
|
entry.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Extensions:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
1a. POIFS throws an exception if the file does not
|
|
|
|
|
exist.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</table>
|
|
|
|
|
</section>
|
|
|
|
|
<section><title>Use Case 6: Write new file to file system</title>
|
|
|
|
|
<table>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Primary Actor:</em></td>
|
|
|
|
|
<td>POIFS client</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Scope:</em></td>
|
|
|
|
|
<td>POIFS</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Level:</em></td>
|
|
|
|
|
<td>Summary</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Stakeholders and Interests:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
* POIFS client- wants to add a new file to the file
|
|
|
|
|
system<br/>
|
|
|
|
|
* POIFS - knows how to manage the file system
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Precondition:</em></td>
|
|
|
|
|
<td>The specified file does not yet exist in the file
|
|
|
|
|
system</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Minimal Guarantee:</em></td>
|
|
|
|
|
<td>None</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Main Success Guarantee:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
1. The POIFS client provides a file name<br/>
|
|
|
|
|
2. POIFS creates a new Property Table entry for the
|
|
|
|
|
new file<br/>
|
|
|
|
|
3. POIFS provides the POIFS client with an
|
|
|
|
|
<code>OutputStream</code> to write to.<br/>
|
|
|
|
|
4. The POIFS client writes data to the provided
|
|
|
|
|
<code>OutputStream</code>.<br/>
|
|
|
|
|
5. The POIFS client closes the provided
|
|
|
|
|
<code>OutputStream</code><br/>
|
|
|
|
|
6. POIFS updates the Property Table entry with the
|
|
|
|
|
new file's size
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Extensions:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
1a. POIFS throws an exception if a file with the
|
|
|
|
|
specified name already exists in the file
|
|
|
|
|
system.<br/>
|
|
|
|
|
1b. POIFS throws an exception if the file name is
|
|
|
|
|
too long. The limit on file name length is 31
|
|
|
|
|
characters.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</table>
|
|
|
|
|
</section>
|
|
|
|
|
<section><title>Use Case 7: Read existing file from file system</title>
|
|
|
|
|
<table>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Primary Actor:</em></td>
|
|
|
|
|
<td>POIFS client</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Scope:</em></td>
|
|
|
|
|
<td>POIFS</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Level:</em></td>
|
|
|
|
|
<td>Summary</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Stakeholders and Interests:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
* POIFS client- wants to read a file from the file
|
|
|
|
|
system<br/>
|
|
|
|
|
* POIFS - knows how to manage the file system
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Precondition:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
* The file system has been read (use case 1, read
|
|
|
|
|
existing file system) or has been created and
|
|
|
|
|
written to (use case 3, create new file system;
|
|
|
|
|
use case 6, write new file to file system).<br/>
|
|
|
|
|
* The specified file exists in the file system.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Minimal Guarantee:</em></td>
|
|
|
|
|
<td>None</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Main Success Guarantee:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
* The POIFS client provides the name of a file to be read <br/>
|
|
|
|
|
* POIFS provides an <code>InputStream</code> to read from. <br/>
|
|
|
|
|
* The POIFS client reads from the <code>InputStream</code>.<br/>
|
|
|
|
|
* The POIFS client closes the <code>InputStream</code>.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Extensions:</em></td>
|
|
|
|
|
<td>1a. POIFS throws an exception if no file with the
|
|
|
|
|
specified name exists.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</table>
|
|
|
|
|
</section>
|
|
|
|
|
<section><title>Use Case 8: Read file system directory</title>
|
|
|
|
|
<table>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Primary Actor:</em></td>
|
|
|
|
|
<td>POIFS client</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Scope:</em></td>
|
|
|
|
|
<td>POIFS</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Level:</em></td>
|
|
|
|
|
<td>Summary</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Stakeholders and Interests:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
* POIFS client- wants to know what files exist in
|
|
|
|
|
the file system<br/>
|
|
|
|
|
* POIFS - knows how to manage the file system
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Precondition:</em></td>
|
|
|
|
|
<td>The file system has been read (use case 1, read
|
|
|
|
|
existing file system) or created (use case 3, create
|
|
|
|
|
new file system)</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Minimal Guarantee:</em></td>
|
|
|
|
|
<td>None</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Main Success Guarantee:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
1. The POIFS client requests the file system
|
|
|
|
|
directory.
|
|
|
|
|
2. POIFS returns an <code>Iterator</code>. The
|
|
|
|
|
<code>Iterator</code> will not include the root
|
|
|
|
|
entry in the Property Table, and may be an
|
|
|
|
|
<code>Iterator</code> over an empty
|
|
|
|
|
<code>Collection</code>.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Extensions:</em></td>
|
|
|
|
|
<td>None</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</table>
|
|
|
|
|
</section>
|
|
|
|
|
<section><title>Use Case 9: Read file</title>
|
|
|
|
|
<table>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Primary Actor:</em></td>
|
|
|
|
|
<td>POIFS</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Scope:</em></td>
|
|
|
|
|
<td>POIFS</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Level:</em></td>
|
|
|
|
|
<td>Summary</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Stakeholders and Interests:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
POIFS - POIFS needs to read a file, or something
|
|
|
|
|
resembling a file (i.e., the Property Table, the
|
|
|
|
|
Small Block Array, or the Small Block Allocation
|
|
|
|
|
Table)
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Precondition:</em></td>
|
|
|
|
|
<td>None</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Minimal Guarantee:</em></td>
|
|
|
|
|
<td>None</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Main Success Guarantee:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
1. POIFS begins with a start block, a file size, and
|
|
|
|
|
a flag indicating whether to use the Big Block
|
|
|
|
|
Allocation Table or the Small Block Allocation
|
|
|
|
|
Table<br/>
|
|
|
|
|
2. POIFS returns an <code>InputStream</code>.<br/>
|
|
|
|
|
3. Reads from the <code>InputStream</code> are
|
|
|
|
|
performed by walking the specified Block
|
|
|
|
|
Allocation Table and reading the blocks
|
|
|
|
|
indicated.<br/>
|
|
|
|
|
4. POIFS closes the <code>InputStream</code> when
|
|
|
|
|
finished reading the file, or its client wants to
|
|
|
|
|
close the <code>InputStream</code>.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Extensions:</em></td>
|
|
|
|
|
<td>3a. An exception will be thrown if the specified Block
|
|
|
|
|
Allocation Table is corrupt, as evidenced by an index
|
|
|
|
|
pointing to a non-existent block, or by a chain
|
|
|
|
|
extending past the known size of the file.</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</table>
|
|
|
|
|
</section>
|
|
|
|
|
<section><title>Use Case 10: Rename existing file in the file system</title>
|
|
|
|
|
<table>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Primary Actor:</em></td>
|
|
|
|
|
<td>POIFS client</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Scope:</em></td>
|
|
|
|
|
<td>POIFS</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Level:</em></td>
|
|
|
|
|
<td>Summary</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Stakeholders and Interests:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
* POIFS client- wants to rename an existing file in
|
|
|
|
|
the file system.<br/>
|
|
|
|
|
* POIFS - knows how to manage the file system.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Precondition:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
* The file system is has been read (use case 1, read
|
|
|
|
|
existing file system) or has been created and
|
|
|
|
|
written to (use case 3, create new file system;
|
|
|
|
|
use case 6, write new file to file system.<br/>
|
|
|
|
|
* The specified file exists in the file system.<br/>
|
|
|
|
|
* The new name for the file does not duplicate
|
|
|
|
|
another file in the file system.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Minimal Guarantee:</em></td>
|
|
|
|
|
<td>None</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Main Success Guarantee:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
1. POIFS updates the Property Table entry for the
|
|
|
|
|
specified file with its new name.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
<tr>
|
|
|
|
|
<td><em>Extensions:</em></td>
|
|
|
|
|
<td>
|
|
|
|
|
* 1a. If the old file name is not in the file
|
|
|
|
|
system, POIFS throws an exception.<br/>
|
|
|
|
|
* 1b. If the new file name already exists in the
|
|
|
|
|
file system, POIFS throws an exception.<br/>
|
|
|
|
|
* 1c. If the new file name is too long (the limit is
|
|
|
|
|
31 characters), POIFS throws an exception.
|
|
|
|
|
</td>
|
|
|
|
|
</tr>
|
|
|
|
|
</table>
|
|
|
|
|
</section>
|
|
|
|
|
</section>
|
|
|
|
|
</body>
|
|
|
|
|
</document>
|
