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    <title>Quality Of Service and Admin Properties</title>
    <prepared></prepared>
    <docno></docno>
    <date>2000-05-29</date>
    <rev></rev>
    <file>ch_QoS.xml</file>
  </header>

  <section>
    <title>Quality Of Service and Admin Properties</title>
    <p>This chapter explains the allowed properties it is possible to set for this
      application. </p>

    <section>
      <title>Quality Of Service</title>
      <p>The cosEventDomain application supports the following QoS settings:</p>
      <table>
        <row>
          <cell align="center" valign="middle"><em>QoS</em></cell>
          <cell align="center" valign="middle"><em>Range</em></cell>
          <cell align="center" valign="middle"><em>Default</em></cell>
        </row>
        <row>
          <cell align="left" valign="middle">CycleDetection</cell>
          <cell align="left" valign="middle">AuthorizeCycles/ForbidCycles</cell>
          <cell align="left" valign="middle">ForbidCycles</cell>
        </row>
        <row>
          <cell align="left" valign="middle">DiamondDetection</cell>
          <cell align="left" valign="middle">AuthorizeDiamonds/ForbidDiamonds</cell>
          <cell align="left" valign="middle">ForbidDiamonds</cell>
        </row>
        <tcaption>Supported QoS settings</tcaption>
      </table>
<br></br><br></br><br></br><br></br>      <p><em>Comments on the table 'Supported QoS Settings':</em></p>
      <taglist>
        <tag><em>CycleDetection</em></tag>
        <item>If a cycle is created, the user <em>must</em> be aware of the fact
         that unless they set timeout on events, events that are not filtered
         will loop endlessly through the topology.</item>
        <tag><em>DiamondDetection</em></tag>
        <item>A Diamond in this context, means that the same
         event may reach a point in the graph by more than one route 
         (i.e. transitive). Hence, it is possible that multiple copies
         are delivered.</item>
      </taglist>
    </section>

    <section>
      <title>Setting Quality Of Service</title>
      <p>Assume we have a Consumer Admin object which we want to change
        the current Quality of Service. Typical usage:</p>
      <code type="none"><![CDATA[
QoS = 
   [#'CosNotification_Property'
    {name='CosEventDomainAdmin':'DiamondDetection'(), 
     value=any:create(orber_tc:short(),
     'CosEventDomainAdmin':'AuthorizeDiamonds'())},
    #'CosNotification_Property'
    {name='CosEventDomainAdmin':'CycleDetection'(), 
     value=any:create(orber_tc:short(),
     'CosEventDomainAdmin':'ForbidCycles'())}],
'CosEventDomainAdmin_EventDomain':set_qos(ED, QoS),
      ]]></code>
      <p>If it is not possible to set the requested QoS the <c><![CDATA[UnsupportedQoS]]></c>
        exception is raised, which includes a sequence of <c><![CDATA[PropertyError]]></c>'s
        describing which QoS, possible range and why is not allowed. The error
        codes are:</p>
      <list type="bulleted">
        <item>UNSUPPORTED_PROPERTY - QoS not supported for this type of target object.</item>
        <item>UNAVAILABLE_PROPERTY - due to current QoS settings the given property
         is not allowed.</item>
        <item>UNSUPPORTED_VALUE - property value out of range; valid range is returned.</item>
        <item>UNAVAILABLE_VALUE - due to current QoS settings the given value is
         not allowed; valid range is returned.</item>
        <item>BAD_PROPERTY - unrecognized property.</item>
        <item>BAD_TYPE - type of supplied property is incorrect.</item>
        <item>BAD_VALUE - illegal value.</item>
      </list>
      <p>The CosEventDomainAdmin_EventDomain interface also supports an operation
        called <c><![CDATA[validate_qos/2]]></c>. The purpose of this operations is to check
        if a QoS setting is supported by the target object and if so, the operation
        returns additional properties which could be optionally added as well.</p>
    </section>

    <section>
      <title>Admin Properties</title>
      <p>The OMG specification do not contain any definitions of Admin Properties.
        Hence, the cosEventDomain application currently does not support any Admin
        Properties.</p>
    </section>
  </section>
</chapter>

