DDS_LatencyBudgetQosPolicy Struct Reference

Provides a hint as to the maximum acceptable delay from the time the data is written to the time it is received by the subscribing applications. More...

Data Fields
struct DDS_Duration_t	duration
	Duration of the maximum acceptable delay.

Detailed Description

Provides a hint as to the maximum acceptable delay from the time the data is written to the time it is received by the subscribing applications.

This policy is a hint to a DDS implementation; it can be used to change how it processes and sends data that has low latency requirements. The DDS specification does not mandate whether or how this policy is used.

Entity:

DDS_Topic, DDS_DataReader, DDS_DataWriter

Status:

DDS_OFFERED_INCOMPATIBLE_QOS_STATUS, DDS_REQUESTED_INCOMPATIBLE_QOS_STATUS

Properties:

RxO = YES
Changeable = YES

See Also

DDS_PublishModeQosPolicy

DDS_FlowController

Usage

This policy provides a means for the application to indicate to the middleware the urgency of the data communication. By having a non-zero duration, RTI Connext can optimize its internal operation.

RTI Connext uses it in conjunction with DDS_ASYNCHRONOUS_PUBLISH_MODE_QOS DDS_DataWriter instances associated with a DDS_EDF_FLOW_CONTROLLER_SCHED_POLICY DDS_FlowController only. Together with the time of write, DDS_LatencyBudgetQosPolicy::duration determines the deadline of each individual sample. RTI Connext uses this information to prioritize the sending of asynchronously published data; see DDS_AsynchronousPublisherQosPolicy.

Compatibility

The value offered is considered compatible with the value requested if and only if the inequality offered duration <= requested duration evaluates to 'TRUE'.

Field Documentation

struct DDS_Duration_t DDS_LatencyBudgetQosPolicy::duration

Duration of the maximum acceptable delay.

[default] 0 (meaning minimize the delay)