RTI Connext C API  Version 6.1.0
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. More...
 

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

◆ duration

struct DDS_Duration_t DDS_LatencyBudgetQosPolicy::duration

Duration of the maximum acceptable delay.

[default] 0 (meaning minimize the delay)