QoS Configuration

Each persistence group and participant has a set of DDS QoSs. There are six tags:

• <participant_qos>
• <publisher_qos>
• <subscriber_qos>
• <topic_qos>
• <datawriter_qos>
• <datareader_qos>

Each QoS is identified by a name. The QoS can inherit its values from other QoSs described in the XML file. For example:

<datawriter_qos name="DerivedWriterQos" base_name="Lib::BaseWriterQos">
    <history>
        <kind>DDS_KEEP_ALL_HISTORY_QOS</kind>
    </history>
</datawriter_qos>

In the above example, the writer QoS named 'DerivedWriterQos' inherits the values from the writer QoS 'BaseWriterQos' contained in the library 'Lib'. The HistoryQosPolicy kind is set to DDS_KEEP_ALL_HISTORY_QOS.

Each XML tag with an associated name can be uniquely identified by its fully qualified name in C++ style. For more information on tags, see Configuring QoS with XML

The persistence groups and participants can use QoS libraries and profiles to configure their QoS values. For example:

<dds>
  <!- QoS LIBRARY SECTION -->
    <qos_library name="QosLib1">
        <qos_profile name="QosProfile1">
            <datawriter_qos name="WriterQos1">
                <history>
                    <kind>DDS_KEEP_ALL_HISTORY_QOS</kind>
                </history>
            </datawriter_qos>
        </qos_profile>
    </qos_library>
    <!-PERSISTENCE SERVICE SECTION -->
    <persistence_service name="Srv1">
        ...
    <!-PERSISTENCE GROUP SECTION -->
        <persistence_group name="PerGroup1" filter="*">
            <single_publisher>true</single_publisher>
            <single_subscriber>true</single_subscriber>
            <datawriter_qos base_name="QosLib1::QosProfile1"/>
       </persistence_group>
    </persistence_service>
</dds >

For more information about QoS libraries and profiles see Configuring QoS with XML.

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