11.3. DataWriter profiles¶

The DataWriter profiles allow for configuring DataWriters from an XML file. These profiles are defined within the <data_writer> or <publisher> XML tags. Thus, the following XML code snippets are equivalent.

DataWriter profile - Definition method 1

DataWriter profile - Definition method 2

<data_writer profile_name="my_datawriter_profile">
    <topic>
        <!-- TOPIC_TYPE -->
    </topic>
    <qos>
        <!-- QOS -->
    </qos>
    <!-- Other elements -->
</data_writer>

<publisher profile_name="my_publisher_profile">
    <topic>
        <!-- TOPIC_TYPE -->
    </topic>
    <qos>
        <!-- QOS -->
    </qos>
    <!-- Other elements -->
</publisher>

Important

The <data_writer> and <publisher> XML tags are equivalent. Therefore, XML profiles in which the DataWriters are defined with the <publisher> tag are fully compatible with Fast DDS.

11.3.1. DataWriter XML attributes¶

The <data_writer> element has two attributes defined: profile_name and is_default_profile.

Name	Description	Use
`profile_name`	Sets the name under which the `<data_writer>` profile is registered in the DDS Domain, so that it can be loaded later by the DomainParticipant, as shown in Loading and applying profiles.	Mandatory
`is_default_profile`	Sets the `<data_writer>` profile as the default profile. Thus, if a default profile exists, it will be used when no other DataWriter profile is specified at the DataWriter’s creation.	Optional

11.3.2. DataWriter configuration¶

The DataWriter configuration is performed through the XML elements listed in the following table.

Name	Description	Values	Default
`<topic>`	TopicType configuration of the DataWriter.	TopicType
`<qos>`	DataWriter QoS configuration.	QoS
`<times>`	It configures some time related parameters of the DataWriter.	Times
`<unicastLocatorList>`	List of input unicast locators. It expects a LocatorListType.	`<locator>`
`<multicastLocatorList>`	List of input multicast locators. It expects a LocatorListType.	`<locator>`
`<throughputController>`	Limits the output bandwidth of the DataWriter.	Throughput Configuration
`<historyMemoryPolicy>`	Memory allocation kind for DataWriter’s history. See HistoryQosPolicyKind.	HistoryMemoryPolicy	`PREALLOCATED`
`<propertiesPolicy>`	Additional configuration properties.	PropertiesPolicyType
`<userDefinedID>`	Used for `EDPStatic`.	`int16_t`	-1
`<entityID>`	Sets the `entity_id` of the RTPSEndpointQos class.	`int16_t`	-1
`<matchedSubscribersAllocation>`	Sets the limits of the collection of matched DataReaders. See ParticipantResourceLimitsQos.	Allocation Configuration

Example

<?xml version="1.0" encoding="UTF-8" ?>
<dds>
    <profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles" >
        <data_writer profile_name="datawriter_profile_name">
            <topic>
                <!-- TOPIC_TYPE -->
            </topic>

            <qos>
                <!-- QOS -->
            </qos>

            <times> <!-- writerTimesType -->
                <initialHeartbeatDelay>
                    <sec>0</sec>
                    <nanosec>12</nanosec>
                </initialHeartbeatDelay>

                <heartbeatPeriod>
                    <sec>3</sec>
                    <nanosec>0</nanosec>
                </heartbeatPeriod>

                <nackResponseDelay>
                    <sec>0</sec>
                    <nanosec>5</nanosec>
                </nackResponseDelay>

                <nackSupressionDuration>
                    <sec>0</sec>
                    <nanosec>0</nanosec>
                </nackSupressionDuration>
            </times>

            <unicastLocatorList>
                <!-- LOCATOR_LIST -->
                <locator>
                    <udpv4/>
                </locator>
            </unicastLocatorList>

            <multicastLocatorList>
                <!-- LOCATOR_LIST -->
                <locator>
                    <udpv4/>
                </locator>
            </multicastLocatorList>

            <throughputController>
                <bytesPerPeriod>8192</bytesPerPeriod>
                <periodMillisecs>1000</periodMillisecs>
            </throughputController>

            <historyMemoryPolicy>DYNAMIC</historyMemoryPolicy>

            <propertiesPolicy>
                <!-- PROPERTIES_POLICY -->
            </propertiesPolicy>

            <userDefinedID>55</userDefinedID>

            <entityID>66</entityID>

            <matchedSubscribersAllocation>
                <initial>0</initial>
                <maximum>0</maximum>
                <increment>1</increment>
            </matchedSubscribersAllocation>

        </data_writer>
<!-->

Note

LOCATOR_LIST means a LocatorListType is expected.
PROPERTIES_POLICY means that the label is a PropertiesPolicyType block.
For QOS details, please refer to QoS.
TOPIC_TYPE is detailed in section TopicType.

11.3.2.1. Times¶

Name	Description	Values	Default
`<initialHeartbeatDelay>`	Initial heartbeat delay.	DurationType	12 ms
`<heartbeatPeriod>`	Periodic heartbeat period.	DurationType	3 s
`<nackResponseDelay>`	Delay to apply to the response of an ACKNACK message.	DurationType	5 ms
`<nackSupressionDuration>`	This time allows the DataWriter to ignore NACK messages for a given period of time right after the data has been sent.	DurationType	0 ms