6.4.2.1 Broker quality of service Enumeration

The BrokerTransportQualityOfService Enumeration DataType is formally defined in Table 141.

The mapping of quality of service to the broker transport specific implementation is defined in 7.3.4.5 for MQTT.

Table 141 – BrokerTransportQualityOfService values
NameValueDescription
NotSpecified0The value is not specified and the value of the parent object shall be used.
BestEffort1The transport shall make the best effort to deliver a message. Worst case this means data loss or data duplication are possible.
AtLeastOnce2The transport guarantees that the message shall be delivered at least once, but duplication is possible. Readers shall de-duplicate based on message id or sequence number.
AtMostOnce3The transport guarantees that the message shall be sent once, but if it is lost it is not sent again.
ExactlyOnce4The transport handshake guarantees that the message shall be delivered to the broker exactly once and not more or less.

The BrokerTransportQualityOfService representation in the AddressSpace is defined in Table 142.

Table 142 – BrokerTransportQualityOfService definition
Attribute Value
BrowseNameBrokerTransportQualityOfService
IsAbstractFalse
References Node Class BrowseName DataType TypeDefinition Others
Subtype of Enumeration defined in OPC 10000-5
HasPropertyVariableEnumStringsLocalizedText []PropertyType
Conformance Units
PubSub Parameters Broker