事件过滤查询语言.pdf

1、OPC Day International 2024Event Filter Query LanguageJulius PfrommerFlorian DwelOPC UA EventsBackgroundJune 25,2024 Fraunhofer IOSBPage 2 Events are emitted by Objects in the information model Events bubble upwards in the information model and are again emitted by each parent Object OPC UA Events ar

2、e“temporary OPC UA Objects”with the properties of the Event(fields)BaseEventType defines standard properties,such as the Events severity Custom subtypes for additional properties Clients access Events via the OPC UA Subscription mechanism MonitoredItem attaches to an Object and listens for the Event

3、s emitted by the Object MonitoredItem defines an EventFilter Which fields to transmit(Select-Clause,required)Which event instances to transmit(Where-Clause,optional)Example EventTypeExample EventFilter Where-ClauseMuch too hard for end-users to defineJune 25,2024 Fraunhofer IOSBPage 3Corresponding C

4、ontentFilter Data TypeLogical Structure of the ContentFilter Users have to supply this“bytecode”Difficult,verbose,error-prone,Not funOPC UA EventFilters are very useful.More people should use them.But the tooling is not-so-great.We have a solution.June 25,2024 Fraunhofer IOSBPage 4OPC UA EventFilter

5、 Query Language Select-ClauseJune 25,2024 Fraunhofer IOSBPage 5 Select-Clause is a comma separated list of SimpleAttributeOperands(SAO)Feature-complete human-readable syntax for expressing SimpleAttributeOperands Default Values for a simplified definition of SAOsDefault TypeDefinitionId is the BaseE

6、ventTypeDefault AttributeId is the Value attributeDefault IndexRange is undefinedTypeDefinitionIdBrowsePathAttributeId IndexRangeSimpleAttributeOperand DefinitionOPC UA EventFilter Query Language Where-Clause(ContentFilter)June 25,2024 Fraunhofer IOSBPage 6 A ContentFilter is a list of filter elemen