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<td bgcolor="#525D76"><font color="#ffffff" size="+1"><font face="Arial,sans-serif"><b>POIFS Use Cases</b></font></font></td>
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<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 1: Read existing file system</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>POIFS client- wants to read content of file
	            system</li>
		
<li>POIFS - understands POIFS file system</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	      	
<li>POIFS client requests POIFS to read a POIFS file
	      	    system, providing an <code>InputStream</code>
	      	    containing POIFS file system in question.</li>
	      	
<li>POIFS reads from the <code>InputStream</code> in
	      	    512 byte blocks</li>
		
<li>POIFS verifies that the first block begins with
		    the well known signature
		    (<code>0xE11AB1A1E011CFD0</code>)</li>
		
<li>POIFS reads the Block Allocation Table from the
		    first block and, if necessary, from the XBAT
		    blocks.</li>
		
<li>POIFS obtains the start block of the Property
		    Table and reads the Property Table (use case 9,
		    read file)</li>
		
<li>POIFS reads the individual entries in the Property
		    Table</li>
		
<li>POIFS obtains the start block of the Small Block
		    Allocation Table and reads the Small Block
		    Allocation Table (use case 9, read file)</li>
		
<li>POIFS obtains the start block of the Small Block
		    store from the first entry in the Property Table
		    and reads the Small Block Array (use case 9, read
		    file)</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>2a. If the last block read is not a 512 byte
	            block, the <code>InputStream</code> is not that of
	            a POIFS file system, and POIFS throws an
	            appropriate exception.</li>
		
<li>3a. If the signature is incorrect, the
		    <code>InputStream</code> is not that of a POIFS
		    file system, and POIFS throws an appropriate
		    exception.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 2: Write file system</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
		
<li>POIFS client- wants to write file system out.</li>
		
<li>POIFS - knows how to write file system out.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>File system has been read (use case 1, read
	            existing file system) and subsequently modified
	            (use case 4, replace file in file system; use case
	            5, delete file from file system; or use case 6,
	            write new file to file system; in any
	            combination)</li>
	      
</ul>
	      
<p align="justify">or</p>
	      
<ul>
	        
<li>File system has been created (use case 3, create
	            new file system)</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	        
<li>POIFS client provides an <code>OutputStream</code>
	            to write the file system to.</li>
		
<li>POIFS gets the sizes of the Property Table and
		    each file in the file system.</li>
		
<li>If any files in the file system requires storage
		    in a Small Block Array, POIFS creates a Small
		    Block Array of sufficient size to hold all of the
		    small files.</li>
		
<li>POIFS calculates the number of big blocks needed
		    to hold all of the large files, the Property
		    Table, and, if necessary, the Small Block Array
		    and the Small Block Allocation Table.</li>
		
<li>POIFS creates a set of big blocks sufficient to
		    store the Block Allocation Table</li>
		
<li>POIFS creates and writes the header block</li>
		
<li>POIFS writes out the XBAT blocks, if needed.</li>
		
<li>POIFS writes out the Small Block Array, if
		    needed</li>
		
<li>POIFS writes out the Small Block Allocation Table,
		    if needed</li>
		
<li>POIFS writes out the Property Table</li>
		
<li>POIFS writes out the large files, if needed</li>
		
<li>POIFS closes the <code>OutputStream</code>.</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>6a. Exceptions writing to the
	            <code>OutputStream</code> will be propagated back
	            to the POIFS client.</li>
		
<li>7a. Exceptions writing to the
	 	    <code>OutputStream</code> will be propagated back
	 	    to the POIFS client.</li>
		
<li>8a. Exceptions writing to the
		    <code>OutputStream</code> will be propagated back
		    to the POIFS client.</li>
		
<li>9a. Exceptions writing to the
		    <code>OutputStream</code> will be propagated back
		    to the POIFS client.</li>
		
<li>10a. Exceptions writing to the
		    <code>OutputStream</code> will be propagated back
		    to the POIFS client.</li>
		
<li>11a. Exceptions writing to the
		    <code>OutputStream</code> will be propagated back
		    to the POIFS client.</li>
		
<li>12a. Exceptions closing the
		    <code>OutputStream</code> will be propagated back
		    to the POIFS client.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 3: Create new file system</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>POIFS client- wants to create a new file
	            system</li>
		
<li>POIFS - knows how to create a new file system</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	      	
<li>POIFS creates an empty Property Table.</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 4: Replace file in file system</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>POIFS client- wants to replace an existing file in
	            the file system</li>
		
<li>POIFS - knows how to manage the file system</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<p align="justify">Either</p>
	      
<ul>
	        
<li>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)</li>
	      
</ul>
	      
<p align="justify">or</p>
	      
<ul>
	        
<li>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)</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	        
<li>POIFS discards storage of the existing file.</li>
  	        
<li>POIFS updates the existing file's entry in the
	            Property Table</li>
	        
<li>POIFS stores the new file's data</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>1a. POIFS throws an exception if the file does not
	            exist.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 5: Delete file from file system</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>POIFS client- wants to remove a file from a file
	            system</li>
		
<li>POIFS - knows how to manage the file system</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<p align="justify">Either</p>
	      
<ul>
	        
<li>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)</li>
	      
</ul>
	      
<p align="justify">or</p>
	      
<ul>
	        
<li>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)</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	      	
<li>POIFS discards the specified file's storage.</li>
	      	
<li>POIFS discards the file's Property Table
	      	    entry.</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>1a. POIFS throws an exception if the file does not
	            exist.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 6: Write new file to file system</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>POIFS client- wants to add a new file to the file
	            system</li>
		
<li>POIFS - knows how to manage the file system</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">The specified file does not yet exist in the file
	        system</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	        
<li>The POIFS client provides a file name</li>
	        
<li>POIFS creates a new Property Table entry for the
	            new file</li>
	        
<li>POIFS provides the POIFS client with an
	            <code>OutputStream</code> to write to.</li>
	        
<li>The POIFS client writes data to the provided
	            <code>OutputStream</code>.</li>
	        
<li>The POIFS client closes the provided
	            <code>OutputStream</code>
</li>
	        
<li>POIFS updates the Property Table entry with the
	            new file's size</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>1a. POIFS throws an exception if a file with the
	            specified name already exists in the file
	            system.</li>
		
<li>1b. POIFS throws an exception if the file name is
		    too long. The limit on file name length is 31
		    characters.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 7: Read existing file from file system</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>POIFS client- wants to read a file from the file
	            system</li>
		
<li>POIFS - knows how to manage the file system</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>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).</li>
		
<li>The specified file exists in the file system.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	        
<li>The POIFS client provides the name of a file to be
	            read</li>
		
<li>POIFS provides an <code>InputStream</code> to read
		    from.</li>
		
<li>The POIFS client reads from the
		    <code>InputStream</code>.</li>
		
<li>The POIFS client closes the
		    <code>InputStream</code>.</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">1a. POIFS throws an exception if no file with the
	        specified name exists.</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 8: Read file system directory</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>POIFS client- wants to know what files exist in
	            the file system</li>
		
<li>POIFS - knows how to manage the file system</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">The file system has been read (use case 1, read
	        existing file system) or created (use case 3, create
	        new file system)</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	        
<li>The POIFS client requests the file system
	            directory.</li>
		
<li>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>.</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 9: Read file</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>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)</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	        
<li>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</li>
		
<li>POIFS returns an <code>InputStream</code>.</li>
		
<li>Reads from the <code>InputStream</code> are
		    performed by walking the specified Block
		    Allocation Table and reading the blocks
		    indicated.</li>
		
<li>POIFS closes the <code>InputStream</code> when
		    finished reading the file, or its client wants to
		    close the <code>InputStream</code>.</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">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.</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
      
<div align="right">
<table cellspacing="0" cellpadding="2" border="0" width="99%">
<tr>
<td bgcolor="#525D76"><font color="#ffffff" size="+0"><font face="Arial,sans-serif"><b>Use Case 10: Rename existing file in the file system</b></font></font></td>
</tr>
<tr>
<td>
<br>
        
<table width="100%" cellspacing="2" cellpadding="2" border="0">
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Primary Actor:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS client</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Scope:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">POIFS</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Level:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">Summary</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Stakeholders and Interests:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>POIFS client- wants to rename an existing file in
	            the file system.</li>
		
<li>POIFS - knows how to manage the file system.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Precondition:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>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.</li>
		
<li>The specified file exists in the file system.</li>
		
<li>The new name for the file does not duplicate
		    another file in the file system.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Minimal Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">None</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Main Success Guarantee:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ol>
	        
<li>POIFS updates the Property Table entry for the
	            specified file with its new name.</li>
	      
</ol>
	    
</font></td>
	  
</tr>
<tr>
	    
<td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000"><B>Extensions:</B></font></td>
	    <td valign="top" bgcolor="#a0ddf0" align="left"><font size="-1" color="#000000">
	      
<ul>
	        
<li>1a. If the old file name is not in the file
	            system, POIFS throws an exception.</li>
		
<li>1b. If the new file name already exists in the
		    file system, POIFS throws an exception.</li>
		
<li>1c. If the new file name is too long (the limit is
		    31 characters), POIFS throws an exception.</li>
	      
</ul>
	    
</font></td>
	  
</tr>
</table>
      
</td>
</tr>
</table>
</div>
<br>
    
</td>
</tr>
</table>
</div>
<br>
</td>
</tr>
</table>
<br>
<table cellpadding="0" cellspacing="0" border="0" width="100%">
<tr>
<td>
<hr size="1" noshade="">
</td>
</tr>
<tr>
<td align="center"><font color="#525D76" size="-1" face="arial,helvetica,sanserif"><i>
              Copyright &copy;2002 Apache Software Foundation
            </i></font></td><td width="5%" align="right"><img src="images/cocoon2-small.jpg" align="right" border="0" vspace="0" hspace="0"></td>
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