DDS_LivelinessChangedStatus Struct Reference

DDS_LIVELINESS_CHANGED_STATUS More...

Data Fields
DDS_Long	alive_count
	The total count of currently alive DDS_DataWriter entities that write the DDS_Topic the DDS_DataReader reads.
DDS_Long	not_alive_count
	The total count of currently not_alive DDS_DataWriter entities that write the DDS_Topic the DDS_DataReader reads.
DDS_Long	alive_count_change
	The change in the alive_count since the last time the listener was called or the status was read.
DDS_Long	not_alive_count_change
	The change in the not_alive_count since the last time the listener was called or the status was read.
DDS_InstanceHandle_t	last_publication_handle
	An instance handle to the last remote writer to change its liveliness.

Detailed Description

DDS_LIVELINESS_CHANGED_STATUS

The DDS_DataReaderListener::on_liveliness_changed callback may be invoked for the following reasons:

• Liveliness is truly lost - a sample has not been received within the timeframe specified in DDS_LivelinessQosPolicy::lease_duration

• Liveliness is recovered after being lost.

• A new matching entity has been discovered.

• A QoS has changed such that a pair of matching entities are no longer matching (such as a change to the DDS_PartitionQosPolicy). In this case, RTI Connext will no longer keep track of the entities' liveliness. Furthermore:
  • If liveliness was maintained: DDS_LivelinessChangedStatus::alive_count will decrease and DDS_LivelinessChangedStatus::not_alive_count will remain the same.
  • If liveliness had been lost: DDS_LivelinessChangedStatus::alive_count will remain the same and DDS_LivelinessChangedStatus::not_alive_count will decrease.

Examples:

HelloWorld_subscriber.c.

Field Documentation

DDS_Long DDS_LivelinessChangedStatus::alive_count

The total count of currently alive DDS_DataWriter entities that write the DDS_Topic the DDS_DataReader reads.

DDS_Long DDS_LivelinessChangedStatus::not_alive_count

The total count of currently not_alive DDS_DataWriter entities that write the DDS_Topic the DDS_DataReader reads.

DDS_Long DDS_LivelinessChangedStatus::alive_count_change

The change in the alive_count since the last time the listener was called or the status was read.

DDS_Long DDS_LivelinessChangedStatus::not_alive_count_change

The change in the not_alive_count since the last time the listener was called or the status was read.

DDS_InstanceHandle_t DDS_LivelinessChangedStatus::last_publication_handle

An instance handle to the last remote writer to change its liveliness.