7.5.25 TRANSFER_MODE QosPolicy

The TRANSFER_MODE QosPolicy configures the properties of a Zero Copy DataWriter. It contains the member listed in the following table.

Table 7.71 DDS_TransferModeQosPolicy

Type	Field Name	Description
DDS_Boolean	enable_data_consistency_check	Enables a Zero Copy DataWriter to send a special sequence number as a part of its inline Qos. This sequence number is used by a Zero Copy DataReader to check for sample consistency in the is_data_consistent() operation . For more details, see 23.5.1.3 Checking data consistency with Zero Copy transfer over shared memory. Default: true

7.5.25.1 Properties

This QosPolicy cannot be modified after the DataWriter is created.

Since it is only for DataWriters, there are no compatibility restrictions for how it is set on the publishing and subscribing sides.

7.5.25.2 Related QosPolicies

None.

7.5.25.3 Applicable Entities

7.3 DataWriters

7.5.25.4 System Resource Considerations

With enable_data_consistency_check set to true, a Zero Copy DataWriter sends an additional sequence number as part of its inline Qos with every write operation. The use of this inline QoS creates a small additional wire-payload, consuming extra bandwidth and serialization/deserialization time.

© 2020 RTI