The BrokerTransportQualityOfService Enumeration DataType is formally defined in Table 123.
The mapping of quality of service to the broker transport specific implementation is defined in 7.3.4.5 for AMQP and 7.3.5.5 for MQTT.
Table 123 – BrokerTransportQualityOfService values
|
Name |
Value |
Description |
|
NotSpecified |
0 |
The value is not specified and the value of the parent object shall be used. |
|
BestEffort |
1 |
The transport shall make the best effort to deliver a message. Worst case this means data loss or data duplication are possible. |
|
AtLeastOnce |
2 |
The 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. |
|
AtMostOnce |
3 |
The transport guarantees that the message shall be sent once, but if it is lost it is not sent again. |
|
ExactlyOnce |
4 |
The 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 124.
Table 124 – BrokerTransportQualityOfService definition
|
Attribute |
Value |
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|
BrowseName |
BrokerTransportQualityOfService |
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|
IsAbstract |
False |
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|
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
Others |
|
Subtype of Enumeration defined in OPC 10000-5 |
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|
HasProperty |
Variable |
EnumStrings |
LocalizedText [] |
PropertyType |
|
|
Conformance Units |
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|
PubSub Parameters Broker |
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