2.1. DataKindΒΆ

The eProsima Fast DDS Statistics Backend records statistics data of different nature, as provided by eProsima Fast DDS Statistics Module, e.g., latency or message count. We refer to the nature of these data values as their DataKind.

  • FASTDDS_LATENCY: The latency between a write operation in the data writer and the moment the data is available in the data reader.

  • NETWORK_LATENCY: The latency in the communication between two locators.

  • PUBLICATION_THROUGHPUT: Amount of data (in Mb/s) sent by a data writer.

  • SUBSCRIPTION_THROUGHPUT: Amount of data (in Mb/s) received by a data reader.

  • RTPS_PACKETS_SENT: Amount of packets sent from a participant to a locator.

  • RTPS_BYTES_SENT: Amount of bytes sent from a participant to a locator.

  • RTPS_PACKETS_LOST: Amount of packets lost from a participant to a locator.

  • RTPS_BYTES_LOST: Amount of bytes lost from a participant to a locator.

  • RESENT_DATA: Amount of DATA/DATAFRAG sub-messages that had to be resent from a data writer.

  • HEARTBEAT_COUNT: Amount of HEARTBEATs that a data writer sends.

  • ACKNACK_COUNT: Amount of ACKNACKs that a data reader sends.

  • NACKFRAG_COUNT: Amount of NACKFRAGs that a data reader sends.

  • GAP_COUNT: Amount of GAPs that a data writer sends.

  • DATA_COUNT: Amount of DATA/DATAFRAGs that a data writer sends.

  • PDP_PACKETS: Amount of PDP packets sent by a participant.

  • EDP_PACKETS: Amount of EDP packets sent by a participant.

  • DISCOVERY_TIME: Time when a participant discovers another DDS entity.

  • SAMPLE_DATAS: Amount of DATA/DATAFRAGs needed to send a single sample.

Each data kind may relate to one or two entities where they are measured. For example, a FASTDDS_LATENCY is always measured between a data data writer and a data reader, whereas PDP_PACKETS is always measured in a participant, with no other entity involved in the measurement. The following table describes which entity kinds are involved in the measurement of each data kind:

Signature

Source Entity

Target Entity

FASTDDS_LATENCY

DataWriter

DataReader

NETWORK_LATENCY

Locator

Locator

PUBLICATION_THROUGHPUT

DataWriter

SUBSCRIPTION_THROUGHPUT

DataReader

RTPS_PACKETS_SENT

DomainParticipant

Locator

RTPS_BYTES_SENT

DomainParticipant

Locator

RTPS_PACKETS_LOST

DomainParticipant

Locator

RTPS_BYTES_LOST

DomainParticipant

Locator

RESENT_DATA

DataWriter

HEARTBEAT_COUNT

DataWriter

ACKNACK_COUNT

DataReader

NACKFRAG_COUNT

DataReader

GAP_COUNT

DataWriter

DATA_COUNT

DataWriter

PDP_PACKETS

DomainParticipant

EDP_PACKETS

DomainParticipant

DISCOVERY_TIME

DomainParticipant

DDSEntity

SAMPLE_DATAS

DataWriter