17.1.4.4. InstanceStateKind

enum eprosima::fastdds::dds::InstanceStateKind

Indicates if the samples are from an alive DataWriter or not.

For each instance, the middleware internally maintains an instance state. The instance state can be:

  • ALIVE_INSTANCE_STATE indicates that (a) samples have been received for the instance, (b) there are alive DataWriter entities writing the instance, and (c) the instance has not been explicitly disposed (or else more samples have been received after it was disposed).

The precise behavior events that cause the instance state to change depends on the setting of the OWNERSHIP QoS:

The instance state available in the

SampleInfo is a snapshot of the instance state of the instance at the time the collection was obtained (i.e. at the time read or take was called). The instance state is therefore the same for all samples in the returned collection that refer to the same instance.

Values:

enumerator ALIVE_INSTANCE_STATE = 0x0001 << 0

Instance is currently in existence.

enumerator NOT_ALIVE_DISPOSED_INSTANCE_STATE = 0x0001 << 1

Not alive disposed instance. The instance has been disposed by a DataWriter.

enumerator NOT_ALIVE_NO_WRITERS_INSTANCE_STATE = 0x0001 << 2

Not alive no writers for instance. None of the DataWriter objects that are currently alive (according to the LIVELINESS QoS) are writing the instance.