QoS

QoS (Quality of Service) in DDS (Data Distribution Service) are a set of configurable parameters that control the behavior of a DDS system, such as resource consumption, fault tolerance, and communication reliability.

Each entity (Topic, DataReader, DataWriter, Publisher, Subscriber, and DomainParticipant) has associated QoS that is comprised of individual QoS policies each one configuring different aspects of the entity behavior.

For example, the RELIABILITY QoS policy is used to configure the reliability of the communication between DataWriters and DataReaders.

Some QoS policies have request/offer semantic. For example, if a DataReader requests to receive data reliably by configuring the RELIABILITY QoS policy, the corresponding DataWriter must offer that level of reliability for communication to happen. If the DataWriter offers best-effort reliability, communication will not occur.

The capability of configuring a DDS system using QoS is extremely important to guarantee an efficient usage of available resources such as memory, CPU, and bandwidth. In addition, QoS allows to configure end to end

Additional Information on this Topic from RTI

• Connext DDS - Comprehensive Summary of QoS Policies (Cheat Sheet)