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
|
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 142.
Table 142 – 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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