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@fornaran
fornaran authored Oct 9, 2024
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Expand Up @@ -171,12 +171,14 @@ <h2>Semantics of Permission, Prohibition, and Obligation</h2>
<li>Refinement (connected to an Action, to an AssetCollection, or to a PartyCollection using the
odrl:refinement property) has a property called <b>satisfaction state</b>
which can take the values of <b>satisfied</b> or <b>not-satisfied</b>.
<li>In the <b>access control scenario</b>, the value of the satisfaction state of a Refinement
<ul>
<li>In the <b>access control scenario</b>, the value of the satisfaction state of a Refinement
is computed according to the action that an agent <b>attempts</b> to perform on digital resources.</li>

<li>In the <b>monitoring scenario</b>, the value of the satisfaction state of a Refinement is
<li>In the <b>monitoring scenario</b>, the value of the satisfaction state of a Refinement is
computed according to the actual actions that are performed by the agents and that are
represented in the <b>state of the world</b>.</li>
</ul>

<li>Action (connected to the Rule with the odrl:action property) has a property called <b>performance state</b>
which initially takes the values <b>not-performed</b> and
can become <b>performed</b> when an action with all the properties values (i.e. <code>type</code>,
Expand Down Expand Up @@ -209,12 +211,12 @@ <h3>Expected behaviour of the ODRL Evaluator</h3>
The evaluation of these Conditions, Constraints and Refinements determine whether the Permission is active or not.
In particular, a Permission is <b>active</b> if:
</p>
<ul>
<li>all the existing constraints of the Rule are satisfied;</li>
<li>all the existing conditions (duties of the Rule) are fulfilled or inactive; </li>
<ol>
<li>all the existing constraints of the Rule are satisfied and;</li>
<li>all the existing conditions (duties of the Rule) are fulfilled or inactive and; </li>
<li>only for the access control scenario: all the existing refinements of the
Action, AssetCollection, PartyCollection are satisfied by the attempted action.</li>
</ul>
</ol>
<p> <!-- definition of active/inactive -->
If the Permission is active, the action is permitted. If one of those conditions is not met, the Permission is <b>inactive</b>. When an action, which is regulated by an <b>active</b> permission is performed, the permission is used by such an action.
</p>
Expand All @@ -229,13 +231,18 @@ <h3>Expected behaviour of the ODRL Evaluator</h3>
In the <b>monitoring scenario</b>: when an action is <b>performed</b> (and it is represented in the state of the world),
if there is no active permission to do so (i.e. there is no active permission regulating a class
of action to which the executed action belongs) and the default setting for the ODRL Evaluator
is set to "everything is prohibited unless explicitly permitted" a violation should be generated.
is set to "everything is prohibited unless explicitly permitted" a violation should be generated.
In the following examples of permissions, as we will analyse one permission at a time, we will not deal with the
generation of violations for permissions.
</p>

<!--The life cycle of a permission is depicted in the figure below (states with the double outline are terminal states):<br>
<img src="ODRLPermission.png">
-->
<h3>Evaluation of constraints</h3>
<h3>Evaluation of Constraints</h3>
<p>Please note that namespaces are used, so that <code>http://example.com/constraint/</code> is simplified by
"<code>constraint:</code>", <code>http://example.com/policy/</code> is simplified by "<code>policy:</code>", etc.</p>

<h4>Example of a constrained permission</h4>
<p>
<b>Example description</b>
Expand All @@ -244,9 +251,9 @@ <h4>Example of a constrained permission</h4>
<!-- General description of the case -->
A permission may not impose duties (like making a payment), but may have the action limited (in time, in space, etc.).
This is the situation of the following case, similar to <a href="https://www.w3.org/TR/odrl-model/#constraint-rule">Example 13</a>
in the ODRL Information Model 2.2. The permission below allows the target asset <code>http://example.com/document:1234</code> to be distributed,
in the ODRL Information Model 2.2. The permission below allows the target asset <code>document:1234</code> to be distributed,
it includes the constraint that the permission may only be exercised until 2018-01-01.
The permission is granted by the organization identified by the URL <code>http://example.com/party/16</code>.
The permission is granted by the organization <code>party:16</code>.
</p>

<pre>
Expand Down Expand Up @@ -281,7 +288,7 @@ <h4>Example of a constrained permission</h4>
<ul>
<li>(E-13-1) If the attempted action belongs to the class of actions regulated by the Permission
(i.e.: its <code>type</code> is <code>distribute</code> and its <code>object</code> is equal to
the target of the permission <code>http://example.com/document:1234</code>)
the target of the permission <code>document:1234</code>)
and the Permission is active then the action can be executed. </li>
<li>(E-13-2) If the attempted action belongs to the class of actions regulated by the Permission, but the
Permission is inactive, assuming that only this Permission is considered
Expand All @@ -291,7 +298,7 @@ <h4>Example of a constrained permission</h4>
</ul>
<p>
The table below shows the input and the output of the Evaluator in the different cases.
Please note that namespaces are used, so that <code>http://example.com/constraint/</code> is simplified by "<code>constraint:</code>", <code>http://example.com/policy/</code> is simplified by "<code>policy:</code>", etc.

</p>
<table border="1" style="font-size:small;">
<tr>
Expand All @@ -300,20 +307,28 @@ <h4>Example of a constrained permission</h4>
<th style="color:darkblue">World</th>
<th style="color:darkred">satisfaction of <br><code>constraint:1</code></th>
<th style="color:darkred"><kbd>access control</kbd><br/>activation of <br><code>policy:13</code></th>
<th style="color:darkblue">Attempted Action</th>
<th style="color:darkred"><kbd>access control</kbd><br/>Output of the Evaluator </th>
</tr>
<tr>
<td>E13-1</td>
<td>policy:13</td>
<td>We are in 2017</td>
<td>satisfied</td>
<td>active</td>
<td><code>distribute</code><br>
<code>document:1234</code></td>
<td>attempted action can be executed</td>
</tr>
<tr>
<td>E13-2</td>
<td>policy:13</td>
<td>We are in 2019</td>
<td>not-satisfied</td>
<td>inactive</td>
<td><code>distribute</code><br>
<code>document:1234</code></td>
<td>attempted action can not be executed</td>
</tr>
</table>

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