Creating and Configuring Custom FlowControllers with Property QoS

You can create and configure FlowControllers using the PROPERTY QosPolicy (DDS Extension) . The properties must have a prefix of “dds.flow_controller.token_bucket”, followed by the name of the FlowController being created or configured. For example, if you want to create/configure a FlowController named MyFC, all the properties for MyFC should have the prefix “dds.flow_controller.token_bucket.MyFC“.

Table 75 lists the properties that can be set for FlowControllers in the DomainParticipant's PROPERTY QosPolicy (DDS Extension) . A FlowController with the name "dds.flow_controller.token_bucket.<your flow controllername>" will be implicitly created when at least one property using that prefix is specified. Then, to link a DataWriter to your FlowController, use "dds.flow_controller.token_bucket.<your flow controllername>" in the DataWriter's publish_mode.flow_controller_name.

Table 75 FlowController Properties

Property Name prefix with ‘dds.flow_controller.token_bucket. <your flow controller name>	Property Value Description
scheduling_policy	Specifies the scheduling policy to be used. (See Flow Controller Scheduling Policies) May be: DDS_RR_FLOW_CONTROLLER_SCHED_POLICY DDS_EDF_FLOW_CONTROLLER_SCHED_POLICY DDS_HPF_FLOW_CONTROLLER_SCHED_POLICY
token_bucket.max_tokens	Maximum number of tokens than can accumulate in the token bucket. Use -1 for unlimited.
token_bucket.tokens_added_per_period	Number of tokens added to the token bucket per specified period. Use -1 for unlimited.
token_bucket.tokens_leaked_per_period	Number of tokens removed from the token bucket per specified period. Use -1 for unlimited.
token_bucket.period.sec	Period for adding tokens to and removing tokens from the bucket in seconds.
token_bucket.period.nanosec	Period for adding tokens to and removing tokens from the bucket in nanoseconds.
token_bucket.bytes_per_token	Maximum number of bytes allowed to send for each token available.

Example

The following example shows how to set FlowController properties.

Note: Some lines in this example, such as dds.flow_controller.token_bucket.MyFlowController.scheduling_policy, are too long to fit on the page as one line; however in your XML file, they each need to be on a single line.

<participant_qos>
	<property>
		<value>
			<element>
				<name>
	dds.flow_controller.token_bucket.MyFlowController.scheduling_policy
				</name>
				<value>DDS_RR_FLOW_CONTROLLER_SCHED_POLICY</value>
			</element>
			<element>
				<name>
	dds.flow_controller.token_bucket.MyFlowController.token_bucket.period.sec
				</name>
				<value>100</value>
			</element>
			<element>
				<name>
		dds.flow_controller.token_bucket.MyFlowController.
		token_bucket.period.nanosec
				</name>
				<value>0</value>
			</element>
			<element>
				<name>
	dds.flow_controller.token_bucket.MyFlowController.token_bucket.tokens_added_per_period
				</name>
				<value>2</value>
			</element>
			<element>
				<name>
	dds.flow_controller.token_bucket.MyFlowController.token_bucket.tokens_leaked_per_period
				</name>
				<value>2</value>
			</element>
			<element>
				<name>
	dds.flow_controller.token_bucket.MyFlowController.token_bucket.bytes_per_token
				</name>
				<value>1024</value>
			</element>
		</value>
	</property>
</participant_qos>
<datawriter_qos>
	<publish_mode>
		<flow_controller_name>
			dds.flow_controller.token_bucket.MyFlowController
		</flow_controller_name>
		<kind>ASYNCHRONOUS_PUBLISH_MODE_QOS</kind>
	</publish_mode>
</datawriter_qos>

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