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<title>LiveSupport Local storage specification</title>
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<h1>Preface</h1>
This document is part of the <a href="http://livesupport.campware.org/">LiveSupport</a>
project, Copyright © 2004 <a href="http://www.mdlf.org/">Media
Development Loan Fund</a>, under the GNU <a
href="http://www.gnu.org/licenses/gpl.html">GPL</a>.<br>
<ul>
<li>Author: $Author: fgerlits $</li>
<li>Version: $Revision: 1.4 $</li>
<li>Location: $Source: /home/paul/cvs2svn-livesupport/newcvsrepo/livesupport/doc/model/LocalStorage/index.html,v $</li>
</ul>
<h1>Scope</h1>
This document contains the specification of the LiveSupport Local
storage component.<br>
<br>
This document contains embedded <a
href="http://www.w3.org/Graphics/SVG/">SVG</a> figures, thus an SVG
capable browser is needed to view it, or an SVG plugin like <a
href="http://www.adobe.com/svg/">Adobe's SVG Viewer</a>.<br>
<h1>Requirements</h1>
<h2>Overview<br>
</h2>
The purpose of the Local storage component is to store Audio Clips
locally.<br>
<h2>Goals</h2>
The goal of the local storage system is to store Audio Clips locally.
Audio Clips contain audio data bundled with metadata describing it.
Storing locally means that the binary audio data is available not just
as a stream, but also as random seekable file.<br>
The local storage contains Playlists also. These are metadata
files containing a list of Audio Clip IDs with extra (fade in / fade out)
information.</br>
<h2>System functions</h2>
The main system functions are described below. There are three
categories for these functions:<br>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th valign="top">function category<br>
</th>
<th valign="top">meaning<br>
</th>
</tr>
<tr>
<td valign="top">evident<br>
</td>
<td valign="top">Should perform, and the user should be cognizant
that it is performed<br>
</td>
</tr>
<tr>
<td valign="top">hidden<br>
</td>
<td valign="top">Should perform, but not visible to the users.<br>
</td>
</tr>
<tr>
<td valign="top">frill<br>
</td>
<td valign="top">Optional<br>
</td>
</tr>
</tbody>
</table>
<br>
<br>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th valign="top">ref#<br>
</th>
<th valign="top">function<br>
</th>
<th valign="top">category<br>
</th>
</tr>
<tr>
<td valign="top">F1.1<br>
</td>
<td valign="top">Store audio clips<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top">F1.2<br>
</td>
<td valign="top">Provide seekable access to audio data<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top">F1.3<br>
</td>
<td valign="top">Delete stored clips<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top">F1.4<br>
</td>
<td valign="top">Update stored clips<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top">F1.5<br>
</td>
<td valign="top">Search Audio clips by querying metadata<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top">F2.1<br>
</td>
<td valign="top">Create new playlists<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top">F2.2<br>
</td>
<td valign="top">Access playlists for editing<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top">F2.3<br>
</td>
<td valign="top">Delete playlists<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top">F2.4<br>
</td>
<td valign="top">Access playlists for execution<br>
</td>
<td valign="top">evident<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h2>System attributes</h2>
Generic attributes<br>
<br>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th valign="top">ref#<br>
</th>
<th valign="top">attribute<br>
</th>
<th valign="top">details and constraints<br>
</th>
<th valign="top">category<br>
</th>
</tr>
<tr>
<td valign="top">A1.1<br>
</td>
<td valign="top">operating system platform<br>
</td>
<td valign="top">Linux<br>
</td>
<td valign="top">must<br>
</td>
</tr>
<tr>
<td valign="top">A1.2<br>
</td>
<td valign="top">local interface<br>
</td>
<td valign="top">locally callable API<br>
</td>
<td valign="top">must<br>
</td>
</tr>
<tr>
<td valign="top">A1.4<br>
</td>
<td valign="top">supported audio formats<br>
</td>
<td valign="top">Ogg Vorbis, MP3, wav<br>
</td>
<td valign="top">must<br>
</td>
</tr>
<tr>
<td valign="top">A1.5<br>
</td>
<td valign="top">file system level interface<br>
</td>
<td valign="top">adding, updated and delete from the local
storage can be done by moving files within the file system by legacy
tools<br>
</td>
<td valign="top">frill<br>
</td>
</tr>
<tr>
<td valign="top">A1.6<br>
</td>
<td valign="top">uniquely identifiable Audio clips<br>
</td>
<td valign="top">all audio clips should be uniquely identifiable,
even when moved among Local storage systems<br>
</td>
<td valign="top">must<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
Attributes related to system functions<br>
<br>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th valign="top">ref#<br>
</th>
<th valign="top">function<br>
</th>
<th valign="top">ref#<br>
</th>
<th valign="top">attribute<br>
</th>
<th valign="top">details and constraints<br>
</th>
<th valign="top">category<br>
</th>
</tr>
<tr>
<td valign="top">F1.2<br>
</td>
<td valign="top">Provide seekable access to audio data<br>
</td>
<td valign="top">A1.3<br>
</td>
<td valign="top">provide file handle<br>
</td>
<td valign="top">provide randomly seekable file level access to
raw
audio data<br>
</td>
<td valign="top">must<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h2>Essential use cases</h2>
This section lists generic (essential) uses cases, that do not contain
architecture-specific considerations.<br>
<br>
<object type="image/svg+xml" name="essential use cases"
data="EssentialUseCases.svg" width="600" height="780"></object>
<h3>UC-1 Store or update Audio clip<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-1 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Store or update Audio clip<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Storage maintainer </td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To store a new Audio clip in the local storage,
or update (replace) an already stored Audio clip<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Storage maintainer contacts the Local
storage with the aim
of uploading and storing a new Audio Clip. If the uploaded Audio clip
is already stored in Local storage (with respect of having the same
unique id), the stored one is replaced with the uploaded one.<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F1.1, F1.4, A1.6<br>
</td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Storage maintainer connects to the Local storage
with the
intention of storing an Audio clip<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Storage maintainer provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Storage maintainer
and grants
access.<br>
</td>
</tr>
<tr>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The Storage maintainer presents the new Audio
clip data,
including raw audio data and metadata<br>
</td>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The system verifies the received data<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>6.1</b><br>
</td>
<td valign="top">If the presented Audio clip does not contain a
unique id, one is generated.<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>6.2</b><br>
</td>
<td valign="top">If the presented Audio clip contains a unique
id, and there already is an Audio clip stored with the same id, the
stored one is replaced with the uploaded Audio clip.<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>7.</b><br>
</td>
<td valign="top">The system stores the received Audio clip and
notifies the Storage maintainer of the actions taken and the unique id
of the stored clip.<br>
</td>
</tr>
<tr>
<td valign="top"><b>8.</b><br>
</td>
<td valign="top">The Storage maintainer disconnects<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Storage maintainer can not be
authenticated, he is notified, and the use case ends.</li>
<li><b>action 6.2:</b> if the raw audio data of the Audio clip is
currently
being accessed (see UC-4), it can not be deleted. the user is notified
and the use case ends.</li>
</ul>
<br>
<h3>UC-2 Delete Audio clip<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-2 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Delete Audio clip<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Storage maintainer </td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To delete an existing Audio clip in the local
storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Storage maintainer contacts the Local
storage with the aim
of deleting an existing Audio Clip<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F1.3 </td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Storage maintainer connects to the Local storage
with the
intention of deleting an Audio clip<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Storage maintainer provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Storage maintainer
and grants
access.<br>
</td>
</tr>
<tr>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The Storage maintainer presents the unique id of
an Audio clip stored in Local storage for deletion<br>
</td>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The system deletes the Audio clip corresponding
to the presented unique id.<br>
</td>
</tr>
<tr>
<td valign="top"><b>6.</b><br>
</td>
<td valign="top">The Storage maintainer disconnects<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Storage maintainer can not be
authenticated, he is notified, and the use case ends.</li>
<li><b>action 5:</b> if no Audio clip is stored with the presented
id, the Storage maintainer is notified. the use case ends.</li>
<li><b>action 5:</b> if the raw audio data of the Audio clip is
currently being accessed (see UC-4), it can not be deleted. the user is
notified and the use case ends.<br>
</li>
</ul>
<br>
<h3>UC-3 Update Audio clip metadata<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-3 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Update Audio clip metadata<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Storage maintainer </td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To update the metadata of an Audio clip, without
uploading raw audio data again.<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Storage maintainer contacts the Local
storage with the aim
of updating the metadata for an already stored Audio clip<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F1.4 </td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Storage maintainer connects to the Local storage
with the
intention of updating the metadata for an Audio clip<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Storage maintainer provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Storage maintainer
and grants
access.<br>
</td>
</tr>
<tr>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The Storage maintainer presents the unique id of
an Audio clip stored in Local storage and the new metadata for that
Audio clip<br>
</td>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The system verifies the clip id and the metadata<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>6.</b><br>
</td>
<td valign="top">The system replaces the metadata of the Audio
clip with the presented one<br>
</td>
</tr>
<tr>
<td valign="top"><b>7.</b><br>
</td>
<td valign="top">The Storage maintainer disconnects<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Storage maintainer can not be
authenticated, he is notified, and the use case ends.</li>
<li><b>action 5:</b> if no Audio clip is stored with the presented
id, the Storage maintainer is notified. the use case ends.<br>
</li>
</ul>
<br>
<h3>UC-4 Access raw audio data<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-4 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Access raw audio data<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Audio player<br>
</td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To access raw audio of Audio clips stored in the
Local storage.<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Audio player accesses the raw audio data
with the ability of randomly seeking in it.<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F1.2, A1.3<br>
</td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Audio player connects to the Local storage with
the
intention of accessing raw audio data<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Audio player provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Audio player and
grants
access.<br>
</td>
</tr>
<tr>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The Audio player presents the unique id of an
Audio clip stored in Local storage that he wants to access<br>
</td>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The systems looks up the Audio clip, and
provides a seekable handle to the Audio player<br>
</td>
</tr>
<tr>
<td valign="top"><b>6.</b><br>
</td>
<td valign="top">The Audio player accesses the raw audio data,
including seeking in it.<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"><b>7.</b><br>
</td>
<td valign="top">The Audio player closes it's access and
disconnects<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Audio player can not be authenticated, he
is notified, and the use case ends.</li>
<li><b>action 5:</b> if no Audio clip is stored with the presented
id, the Audio player is notified. the use case ends.</li>
</ul>
<br>
<h3>UC-5 Search in metadata<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-5 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Search in metadata<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Storage maintainer<br>
</td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To search in the metadata of audio clips<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Storage maintainer searches through the
stored Audio clips by specifying search criteria for the metadata of
the clips<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F1.5<br>
</td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Storage maintainer connects to the Local storage
with the
intention of searching.<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Storage maintainer provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Storage maintainer
and grants
access.<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The system provides a way of specifying search
criteria with respect to the existing metadata structures<br>
</td>
</tr>
<tr>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The Storage maintainer specifies a search
criteria<br>
</td>
<td valign="top"><b>6.</b><br>
</td>
<td valign="top">The system searches through the metadata of
contained Audio clips, and presents a list of matches<br>
</td>
</tr>
<tr>
<td valign="top"><b>7.</b><br>
</td>
<td valign="top">The Storage maintainer refines his search and
searches again<br>
</td>
<td valign="top"><b>8.</b><br>
</td>
<td valign="top">The system does a new search according to the
refined criteria, and presents the results to the Storage maintainer<br>
</td>
</tr>
<tr>
<td valign="top"><b>9.</b><br>
</td>
<td valign="top">The storage maintainer reviews the results<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"><b>10.</b><br>
</td>
<td valign="top">The storage maintainer disconnects<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Storage maintainer can not be
authenticated, he is notified, and the use case ends.</li>
</ul>
<br>
<h3>UC-6 Create playlist<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-6 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Create playlist<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Storage maintainer </td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To store a new Playlist in the local storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Storage maintainer contacts the Local
storage with the aim of uploading a new Playlist. The Local
storage stores the new metafile under the new ID.<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F2.1<br>
</td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Storage maintainer connects to the Local storage
with the intention of uploading a new Playlist<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Storage maintainer provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Storage maintainer
and grants access.<br>
</td>
</tr>
<tr>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The Storage maintainer presents the new Playlist
ID and the new Playlist metafile<br>
</td>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The system verifies that there is no Playlist yet
in the Local storage with the given ID<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>6.</b><br>
</td>
<td valign="top">The system stores the received Playlist metafile
and notifies the Storage maintainer of the action taken.<br>
</td>
</tr>
<tr>
<td valign="top"><b>7.</b><br>
</td>
<td valign="top">The Storage maintainer disconnects<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Storage maintainer can not be
authenticated, she is notified, and the use case ends.</li>
<li><b>action 5:</b> if there is already a Playlist in the Local storage
with the given ID, the user is notified and the use case ends.</li>
</ul>
<br>
<h3>UC-7 Edit playlist<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-7 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Edit playlist<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Storage maintainer </td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To modify an existing Playlist in the local
storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Storage maintainer contacts the Local
storage with the aim of editing an existing Playlist. The Local
storage retrieves the Playlist and marks it as being edited. The Storage
maintainer modifies the Playlist. The Storage maintainer saves the
modified Playlist, the Local storage stores it in place of the old
Playlist and marks it as no longer being edited.<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F2.2<br>
</td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Storage maintainer connects to the Local storage
with the intention of editing a Playlist<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Storage maintainer provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Storage maintainer
and grants access<br>
</td>
</tr>
<tr>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The Storage maintainer presents a Playlist ID<br>
</td>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The system verifies that there is a Playlist
in the Local storage with the given ID, and it is not currently
being edited<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>6.</b><br>
</td>
<td valign="top">The system marks the Playlist with the given ID
as being edited<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>7.</b><br>
</td>
<td valign="top">The system returns the Playlist metafile with
the given ID and notifies the Storage maintainer of the actions taken<br>
</td>
</tr>
<tr>
<td valign="top"><b>8.</b><br>
</td>
<td valign="top">The Storage maintainer modifies the Playlist<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"><b>9.</b><br>
</td>
<td valign="top">The Storage maintainer presents the new Playlist
metafile for saving<br>
</td>
<td valign="top"><b>10.</b><br>
</td>
<td valign="top">The system verifies that the user had opened this
Playlist earlier<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>11.</b><br>
</td>
<td valign="top">The system stores the new Playlist metafile in
place of the old one, marks it as no longer being edited,
and notifies the Storage maintainer of the actions taken<br>
</td>
</tr>
<tr>
<td valign="top"><b>12.</b><br>
</td>
<td valign="top">The Storage maintainer disconnects.<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Storage maintainer can not be
authenticated, she is notified, and the use case ends.</li>
<li><b>action 5:</b> if there is no Playlist in the Local storage
with the given ID, or if the Playlist is already being edited,
the user is notified and the use case ends.</li>
<li><b>action 10:</b> if the user cannot be identified as the same
that opened the Playlist for editing, the user is notified, and the
use case continues at point 8.</li></ul>
<br>
<h3>UC-8 Delete playlist<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-8 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Delete playlist<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Storage maintainer </td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To delete a Playlist from the local storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Storage maintainer contacts the Local
storage with the aim of deleting a Playlist. The system deletes the
Playlist with the given ID from the Local storage.<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F2.3<br>
</td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Storage maintainer connects to the Local storage
with the intention of deleting a Playlist<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Storage maintainer provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Storage maintainer
and grants access<br>
</td>
</tr>
<tr>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The Storage maintainer presents the ID of the
Playlist to be deleted<br>
</td>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The system verifies that there is a Playlist
in the Local storage with the given ID, and it is not currently being
edited<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>6.</b><br>
</td>
<td valign="top">The system deletes the given Playlist from
the Local storage
and notifies the Storage maintainer of the action taken<br>
</td>
</tr>
<tr>
<td valign="top"><b>7.</b><br>
</td>
<td valign="top">The Storage maintainer disconnects.<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Storage maintainer can not be
authenticated, she is notified, and the use case ends.</li>
<li><b>action 5:</b> if there is no Playlist in the Local storage
with the given ID, or if the Playlist is currently being edited,
the user is notified and the use case ends.</li>
</ul>
<br>
<h3>UC-9 Access playlist<br>
</h3>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>ref#</b> </td>
<td valign="top">UC-9 </td>
</tr>
<tr>
<td valign="top"><b>use case</b> </td>
<td valign="top">Access playlist<br>
</td>
</tr>
<tr>
<td valign="top"><b>type</b> </td>
<td valign="top">primary, essential </td>
</tr>
<tr>
<td valign="top"><b>actors</b> </td>
<td valign="top">Audio player </td>
</tr>
<tr>
<td valign="top"><b>purpose</b> </td>
<td valign="top">To access a Playlist metafile in order to
execute (play) it<br>
</td>
</tr>
<tr>
<td valign="top"><b>overview</b> </td>
<td valign="top">The Audio player contacts the Local
storage with the aim of accessing a Playlist. The Local storage
returns the requested Playlist metafile.<br>
</td>
</tr>
<tr>
<td valign="top"><b>references</b> </td>
<td valign="top">F2.4<br>
</td>
</tr>
</tbody>
</table>
<h4>Typical course of events</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th colspan="2" valign="top">actor action <br>
</th>
<th colspan="2" valign="top">system response <br>
</th>
</tr>
<tr>
<td valign="top"><b>1.</b> </td>
<td valign="top">Audio player connects to the Local storage
with the intention of accessing a Playlist<br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
<tr>
<td valign="top"><b>2.</b> </td>
<td valign="top">The Audio player provides authentication
information </td>
<td valign="top"><b>3.</b> </td>
<td valign="top">The system authenticates the Audio player
and grants access<br>
</td>
</tr>
<tr>
<td valign="top"><b>4.</b><br>
</td>
<td valign="top">The Audio player presents a Playlist ID<br>
</td>
<td valign="top"><b>5.</b><br>
</td>
<td valign="top">The system verifies that there is a Playlist
in the Local storage with the given ID<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><b>6.</b><br>
</td>
<td valign="top">The system returns the requested Playlist metafile
and notifies the Audio player of the action taken<br>
</td>
</tr>
<tr>
<td valign="top"><b>7.</b><br>
</td>
<td valign="top">The Audio player reads the Playlist, and saves
a private copy<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"><b>8.</b><br>
</td>
<td valign="top">The Audio player notifies the Local storage that
it no longer needs the Playlist, and disconnects.<br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
<td valign="top"> <br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Alternate courses</h4>
<ul>
<li><b>action 3:</b> if the Audio player can not be
authenticated, she is notified, and the use case ends.</li>
<li><b>action 5:</b> if there is no Playlist in the Local storage
with the given ID, the user is notified and the use case ends.</li>
</ul>
<br>
<h2>Conceptual model</h2>
The following figure displays the semantic concepts identified for the
Scheduler daemon, and the main associations between the concepts.<br>
<br>
<object type="image/svg+xml" name="essential use cases"
data="Concepts.svg" width="650" height="600"></object>
<br>
<h3>Concepts</h3>
<br>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th valign="top">concept<br>
</th>
<th valign="top">description<br>
</th>
</tr>
<tr>
<td valign="top"><b>Authentication</b><br>
</td>
<td valign="top">Component responsible for doing the
authentications <br>
</td>
</tr>
<td valign="top"><b>Session ID</b><br>
</td>
<td valign="top">An identifier issued by Authentication, to be
used by subsequent operations.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Unique ID<br>
</b> </td>
<td valign="top">A globally unique identifier used to to
differentiate between objects that might even be created on different
systems. Even though the whole space of Id is not known, the Ids must
be unique.<br>
</td>
</tr>
<tr>
<td valign="top"><b>MetaData</b><br>
</td>
<td valign="top">Data about the AudioClip<br>
</td>
</tr>
<tr>
<td valign="top"><b>SearchCriteria<br>
</b></td>
<td valign="top">Describes the search parameters when doing a
search on the MetaData<br>
</td>
</tr>
<tr>
<td valign="top"><b>AudioClip</b><br>
</td>
<td valign="top">The basic unit of audio handled by Local storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>RawAudioData<br>
</b></td>
<td valign="top">The binary audio data contained in an Audio clip<br>
</td>
</tr>
<tr>
<td valign="top"><b>Storage maintainer</b><br>
</td>
<td valign="top">The actor that maintains the contents of the
Local storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>Audio player</b><br>
</td>
<td valign="top">The actor that accesses the raw audio contained
in the Local storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>Playlist</b><br>
</td>
<td valign="top">A metafile containing AudioClip IDs and some
extra (fade in / fade out) information<br>
</td>
</tr>
<tr>
<td valign="top"><b>URL</b><br>
</td>
<td valign="top">The location of a metafile (in the local filesystem)<br>
</td>
</tr>
<tr>
<td valign="top"><b>Token</b><br>
</td>
<td valign="top">An identifier used to match the parts of two-part
operations, e.g., access--release or edit--save<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h3>Associations</h3>
<br>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<th valign="top">source<br>
</th>
<th valign="top">association<br>
</th>
<th valign="top">target<br>
</th>
<th valign="top">description<br>
</th>
</tr>
<tr>
<td valign="top">AudioClip<br>
</td>
<td valign="top">Is identified by<br>
</td>
<td valign="top">UniqueId<br>
</td>
<td valign="top">This is a globally unique id for each Audio clip<br>
</td>
</tr>
<tr>
<td valign="top">AudioClip<br>
</td>
<td valign="top">Is described by<br>
</td>
<td valign="top">MetaData<br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top">AudioClip<br>
</td>
<td valign="top">Contains<br>
</td>
<td valign="top">RawAudioData<br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top">Storage maintainer<br>
</td>
<td valign="top">Is Authenticated by<br>
</td>
<td valign="top">Authentication<br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top">Storage maintainer<br>
</td>
<td valign="top">Searches in<br>
</td>
<td valign="top">MetaData<br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top">Storage maintainer<br>
</td>
<td valign="top">Searches by<br>
</td>
<td valign="top">SearchCriteria<br>
</td>
<td valign="top">The storage maintainer specifies such a
SearchCriteria when doing a search on MetaData<br>
</td>
</tr>
<tr>
<td valign="top">Storage maintainer<br>
</td>
<td valign="top">Manages<br>
</td>
<td valign="top">AudioClip<br>
</td>
<td valign="top">This includes uploading, updating and deleting
AudioClips<br>
</td>
</tr>
<tr>
<td valign="top">Audio player<br>
</td>
<td valign="top">Is Authenticated by<br>
</td>
<td valign="top">Authentication<br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top">Audio player<br>
</td>
<td valign="top">Accesses<br>
</td>
<td valign="top">RawAudioData<br>
</td>
<td valign="top">This is a seekable access to raw audio data.<br>
</td>
</tr>
<tr>
<td valign="top">Playlist<br>
</td>
<td valign="top">Is identified by<br>
</td>
<td valign="top">UniqueId<br>
</td>
<td valign="top">This is a globally unique id for each Playlist<br>
</td>
</tr>
<tr>
<td valign="top">Storage maintainer<br>
</td>
<td valign="top">Manages<br>
</td>
<td valign="top">Playlist<br>
</td>
<td valign="top">This includes creating, editing, deleting and
accessing Playlists<br>
</td>
</tr>
<td valign="top">Playlist<br>
</td>
<td valign="top">Is associated with<br>
</td>
<td valign="top">URL<br>
</td>
<td valign="top">The path of (a copy of) the playlist metafile<br>
</td>
</tr>
<td valign="top">Playlist<br>
</td>
<td valign="top">Is associated with<br>
</td>
<td valign="top">Token<br>
</td>
<td valign="top">An identifier issued by access operations, to be
used for identification by release operations<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h2>System behavior</h2>
The behavior of the system as a whole as experienced from the outside
is discussed in this section.<br>
<h3>System sequence diagrams</h3>
System diagrams are presented for each use case below.<br>
<h4>UC-1 Store or update Audio clip</h4>
<object type="image/svg+xml" name="authenticate user sequence diagram"
data="Storeorupdateaudioclip_SequenceDiagram.svg" width="650"
height="200"></object>
<br>
<h4>UC-2 Delete Audio clip</h4>
<object type="image/svg+xml" name="authenticate user sequence diagram"
data="Deleteaudioclip_SequenceDiagram.svg" width="600" height="200"></object>
<br>
<h4>UC-3 Update Audio clip metadata</h4>
<object type="image/svg+xml" name="authenticate user sequence diagram"
data="UpdateAudioclipmetadata_SequenceDiagram.svg" width="650"
height="200"></object>
<br>
<h4>UC-4 Access raw audio data</h4>
<object type="image/svg+xml" name="authenticate user sequence diagram"
data="Accessrawaudiodata_SequenceDiagram.svg" width="600" height="200"></object>
<br>
<h4>UC-5 Search in metadata</h4>
<object type="image/svg+xml" name="authenticate user sequence diagram"
data="Searchinmetadata_SequenceDiagram.svg" width="650" height="200"></object>
<br>
<h4>UC-6 Create playlist</h4>
<object type="image/svg+xml" name="create playlist sequence diagram"
data="Createplaylist_SequenceDiagram.svg" width="650" height="200"></object>
<br>
<h4>UC-7 Edit playlist</h4>
<object type="image/svg+xml" name="create playlist sequence diagram"
data="Editplaylist_SequenceDiagram.svg" width="650" height="200"></object>
<br>
<h4>UC-8 Delete playlist</h4>
<object type="image/svg+xml" name="create playlist sequence diagram"
data="Deleteplaylist_SequenceDiagram.svg" width="650" height="200"></object>
<br>
<h4>UC-9 Access playlist</h4>
<object type="image/svg+xml" name="create playlist sequence diagram"
data="Accessplaylist_SequenceDiagram.svg" width="650" height="200"></object>
<br>
<h3>System objects</h3>
The following figure shows the system objects and their functions, as
derived from the system sequence diagrams.<br>
<object type="image/svg+xml" name="system behaviour"
data="Systembehaviour.svg" width="450" height="320"></object>
<h3>Contracts</h3>
For all operations exposed in the system sequence diagrams, the
following contracts are defined.<br>
<h4>Contract for Local storage : authenticate</h4>
see Authentication : Authenticate<br>
<h4>Contract for Local storage : existsAudioClip<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">existsAudioClip<br>
(sessionId : SessionId, <br>
audioClipId : UniqueId)<br>
: boolean<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Check if an Audio clip
with the specified id is stored in local storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">true if an Audio clip
with the specified id is stored in Local storage, false otherwise<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td valign="top">none<br>
</td>
<td valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : storeAudioClip<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">storeAudioClip<br>
(sessionId : SessionId, <br>
audioClip : AudioClip)<br>
: UniqueId<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Store a new audio clip
or replace an existing one.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-1<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if this is an AudioClip
update, and the RawAudioData of the already existing AudioClip is is
being accessed (see UC-4), report as an error.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">the unique id of the
stored audio clip<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top">if this is a new audio clip:</td>
<td valign="top">an AudioClip object is created</td>
<td valign="top">instance creation<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">a UniqueId is generated for the new clip<br>
</td>
<td valign="top">instance creation<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the UniqueId is associated with the AudioClip<br>
</td>
<td valign="top">association formed<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">a MetaData object is created and filled with the
presented contents<br>
</td>
<td valign="top">instance creation<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the MetaData is associated with the AudioClip<br>
</td>
<td valign="top">association formed<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">a RawAudioData object is created and filled with
the presented contents<br>
</td>
<td valign="top">instance creation<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the RawAudioData is associated with the AudioClip<br>
</td>
<td valign="top">association formed<br>
</td>
</tr>
<tr>
<td valign="top">if the clip already existed:<br>
</td>
<td valign="top">the contents of MetaData for the AudioClip are
replaced by the presented contents<br>
</td>
<td valign="top">attribute modification<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the contents of RawAudioData for the AudioClip
are replaced by the presented contents<br>
</td>
<td valign="top">attribute modification<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : deleteAudioClip<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">deleteAudioClip<br>
(sessionId : SessionId, <br>
audioClipId : UniqueId)<br>
: void<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Delete an existing Audio
clip<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-2<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if no Audio clip with
the specified id exists, report as an error.<br>
if the RawAudioData for AudioClip is being accessed (see UC-4), report
as an error.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the UniqueId for the AudioClip is deleted<br>
</td>
<td valign="top">instance deletion<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the MetaData for the AudioClip is deleted<br>
</td>
<td valign="top">instance deletion<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the RawAudioData for the AudioClip is deleted<br>
</td>
<td valign="top">instance deletion<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the AudioClip is deleted<br>
</td>
<td valign="top">instance deletion<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : updateAudioClipMetadata<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">updateAudioClipMetadata<br>
(sessionId : SessionId, <br>
audioClipId : UniqueId,<br>
newMetadata : MetaData)<br>
: void<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Update the metadata of
an Audio clip stored in Local storage<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-3<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if no Audio clip with
the specified id exists, report as an error.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the contents of MetaData for the AudioClip are
replaced with the presented contents<br>
</td>
<td valign="top">attribute modification<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : accessRawAudioData<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">accessRawAudioData<br>
(sessionId : SessionId, <br>
audioClipId : UniqueId)<br>
: RawAudioData<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Get access to raw audio
data of an AudioClip<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-4<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if no Audio clip with
the specified id exists, report as an error.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">the RawAudioData for the
AudioClip identified with the supplied UniqueId<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the currentlyAccessing attribute for
RawAudioData for AudioClip is increased by one<br>
</td>
<td valign="top">attribute modification<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : releaseRawAudioData<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">releaseRawAudioData<br>
(sessionId : SessionId, <br>
rawAudioData : RawAudioData)<br>
: void<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Release access for raw
audio data<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-4<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if the specified
RrawAudioData is not stored in Local storage, indicate as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the currentlyAccessing attribute for
RawAudioData for AudioClip is decreased by one<br>
</td>
<td valign="top">attribute modification<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : searchMetadata<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">searchMetadata<br>
(sessionId : SessionId, <br>
criteria : SearchCriteria)<br>
: UniqueId<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Search through the
metadata of stored AudioClips, and return all matching clip ids<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-5<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">A range of Audio clip
ids, for which MetaData matches the supplied search criteria<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="left" valign="top">none<br>
</td>
<td align="center" valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : getAudioClip<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">getAudioClip<br>
(sessionId : SessionId, <br>
audioClipId : UniqueId)<br>
: AudioClip<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Return the contents of
an Audio clip.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">see Playlist editor<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if no Audio clip by the
specified id exists, report as an error.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">The Audio clip,
specified by the supplied id.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="left" valign="top">none<br>
</td>
<td align="center" valign="top"><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : createPlaylist<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">createPlaylist<br>
(sessionId : SessionId, <br>
playlistId : UniqueId)<br>
: void<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Create a new Playlist
metafile.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-6<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if a Playlist with the
given playlistId already exists, report as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"></td>
<td valign="top">a Playlist object is created</td>
<td valign="top">instance creation<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the new Playlist is marked as currently
not being edited<br>
</td>
<td valign="top">attribute modification<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : editPlaylist<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">editPlaylist<br>
(sessionId : SessionId, <br>
playlistId : UniqueId)<br>
: { playlistURL : URL, playlistToken: Token }<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Open a Playlist metafile
for editing.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-7<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if no Playlist with the
given playlistId exists, or if the Playlist has already been marked as
being edited, report as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">a URL of a Playlist
metafile, and a token identifying it<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the Playlist is marked as currently
being edited<br>
</td>
<td valign="top">attribute modification<br>
</td>
</tr>
<td valign="top"><br></td>
<td valign="top">the Playlist metafile and the URL returned are
associated with the token returned<br>
</td>
<td valign="top">association formed<br>
</td>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : savePlaylist<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">savePlaylist<br>
(sessionId : SessionId, <br>
playlistToken : Token, <br>
newPlaylist : Playlist)<br>
: void<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Store a new Playlist
metafile in place of the old one.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-7<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">TODO: decide exactly what
the newPlaylist argument looks like<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if the playlistToken argument
does not match a token generated earlier in this session by editPlaylist(),
report as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">the Playlist has been marked
as being edited in the same session</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top">the Playlist is marked as currently
not being edited<br>
</td>
<td valign="top">attribute modification<br>
</td>
</tr>
<tr>
<td valign="top"></td>
<td valign="top">the playlistToken token and the URL returned earlier
by editPlaylist() together with it are no longer valid</td>
<td valign="top">association broken<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : deletePlaylist<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">deletePlaylist<br>
(sessionId : SessionId, <br>
playlistId : UniqueId)<br>
: void<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Delete a Playlist
metafile.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-8<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if no Playlist with the
given playlistId exists, or if the Playlist is marked as currently
being edited, report as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"></td>
<td valign="top">a Playlist object is deleted</td>
<td valign="top">instance deletion<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : accessPlaylist<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">accessPlaylist<br>
(sessionId : SessionId, <br>
playlistId : UniqueId)<br>
: { playlistURL : URL, playlistToken : Token }<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Access (read) a Playlist
metafile.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-9<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">for this method, it does
not matter whether the Playlist is being edited or not -- the latest
saved state of the Playlist should be returned<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if no Playlist with the
given playlistId exists, report as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">a URL of a Playlist
metafile, and a token identifying it<br>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
</tr>
<td valign="top"><br>
</td>
<td valign="top">the Playlist and the URL returned are
associated with the token returned<br>
</td>
<td valign="top">association formed<br>
</td>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : releasePlaylist<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">releasePlaylist<br>
(sessionId : SessionId, <br>
playlistToken : Token)<br>
: void<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Release the resources
obtained earlier by accessPlaylist().<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-9<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if the playlistToken argument
does not match a token generated earlier in this session by accessPlaylist(),
report as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"></td>
<td valign="top">the playlistToken token and the URL returned earlier
by accessPlaylist() together with it are no longer valid</td>
<td valign="top">association broken<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : existsPlaylist<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">existsPlaylist<br>
(sessionId : SessionId, <br>
playlistId : UniqueId)<br>
: bool<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Check whether a Playlist
metafile with the given playlist ID exists.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-6, UC-7, UC-8, UC-9<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">true or false<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : playlistIsAvailable<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">playlistIsAvailable<br>
(sessionId : SessionId, <br>
playlistId : UniqueId)<br>
: bool<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Check whether a Playlist
metafile with the given playlist ID is available for editing, i.e., exists
and has not been opened for editing yet.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-7<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">true if the playlist exists
and is available; false if either condition fails<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : accessAudioClip<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">accessAudioClip<br>
(sessionId : SessionId, <br>
audioClipId : UniqueId)<br>
: { audioClipURL : URL, audioClipToken : Token }<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Access (read) an Audio
Clip metafile.<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-4<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if no AudioClip with the
given audioClipId exists, report as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">a URL of an AudioClip
metafile, and a token identifying it<br>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
</tr>
<td valign="top"><br>
</td>
<td valign="top">the AudioClip and the URL returned are
associated with the token returned<br>
</td>
<td valign="top">association formed<br>
</td>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<h4>Contract for Local storage : releaseAudioClip<br>
</h4>
<table width="100%" border="0" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td valign="top"><b>Name</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">releaseAudioClip<br>
(sessionId : SessionId, <br>
audioClipToken : Token)<br>
: void<br>
</td>
</tr>
<tr>
<td valign="top"><b>Responsibilities</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">Release the resources
obtained earlier by accessAudioClip().<br>
</td>
</tr>
<tr>
<td valign="top"><b>Type</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">system<br>
</td>
</tr>
<tr>
<td valign="top"><b>Cross-reference</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">UC-4<br>
</td>
</tr>
<tr>
<td valign="top"><b>Notes</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Exceptions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">if the audioClipToken argument
does not match a token generated earlier in this session by accessAudioClip(),
report as an error<br>
</td>
</tr>
<tr>
<td valign="top"><b>Output</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none<br>
</td>
</tr>
<tr>
<td valign="top"><b>Pre-conditions</b><br>
</td>
<td colspan="2" rowspan="1" valign="top">none</td>
</tr>
<tr>
<td valign="top"><b>Post-conditions</b><br>
</td>
<td align="center" valign="top"><b>condition</b><br>
</td>
<td align="center" valign="top"><b>type</b><br>
</td>
</tr>
<tr>
<td valign="top"></td>
<td valign="top">the audioClipToken token and the URL returned earlier
by accessAudioClip() together with it are no longer valid</td>
<td valign="top">association broken<br>
</td>
</tr>
<tr>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
<td valign="top"><br>
</td>
</tr>
</tbody>
</table>
<br>
<br>
</body>
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