DDS_DeadlineQosPolicy Struct Reference

Expresses the maximum duration or deadline within which an instance is expected to be updated. More...

#include <dds_c_infrastructure.h>

Public Attributes
struct DDS_Duration_t	period
	Duration of the deadline period.

Detailed Description

Expresses the maximum duration or deadline within which an instance is expected to be updated.

DDSDataReader expects a new sample updating the value of each instance at least once every period. DDSDataWriter indicates that the application commits to write a new value using the DDSDataWriter for each instance managed by the DDSDataWriter at least once every period.

If a DDSDataReader stops receiving samples, it will take at most (period + (period / 8)) to detect that the deadline has been missed. The deadline period starts again when the next sample is received.

Entity:

DDSTopic, DDSDataReader, DDSDataWriter

Status:

DDS_OFFERED_DEADLINE_MISSED_STATUS, DDS_REQUESTED_DEADLINE_MISSED_STATUS, DDS_OFFERED_INCOMPATIBLE_QOS_STATUS, DDS_REQUESTED_INCOMPATIBLE_QOS_STATUS

Properties:

RxO = YES
Changeable = NO

Usage

This policy is useful for cases where a DDSTopic is expected to have each instance updated periodically. On the publishing side this setting establishes a contract that the application must meet. On the subscribing side the setting establishes a minimum requirement for the remote publishers that are expected to supply the data values.

When RTI Connext DDS Micro 'matches' a DDSDataWriter and a DDSDataReader it checks whether the settings are compatible; that is, offered deadline <= requested deadline; if they are not, the two entities are informed via the DDSListener mechanism of the incompatibility of the QoS settings and communication will not occur.

Assuming that the reader and writer have compatible settings, the fulfillment of this contract is monitored by RTI Connext DDS Micro and the application is informed of any violations by means of the proper DDSListener.

Compatibility

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

Member Data Documentation

period

struct DDS_Duration_t DDS_DeadlineQosPolicy::period

Duration of the deadline period.

[default] DDS_DURATION_INFINITE

[range] [1 nanosec, 1 year] or DDS_DURATION_INFINITE