The OrderedListTypeis a base type to manage an ordered list of Objects. It is formally defined in Table 64.
Table 64– OrderedListType Definition
Attribute |
Value |
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BrowseName |
OrderedListType |
||||
IsAbstract |
False |
||||
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
Other |
Subtype of the BaseObjectTypedefined in 6.2i.e. inheriting the InstanceDeclarations of that Node. |
|||||
HasOrderedComponent |
Object |
<OrderedObject> |
|
BaseObjectType |
OP |
HasProperty |
Variable |
NodeVersion |
String |
PropertyType |
O |
GeneratesEvent |
ObjectType |
GeneralModelChangeEventType |
|
|
|
Conformance Units |
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Base Info OrderedList |
The <OrderedObject> Objectrepresents the ordered Objectsmanaged by Instances of the OrderedListType. The order is provided by the 0:HasOrderedComponent Referencesto the Objects. As not all Clientsconsider the order returned by the Browse Service(e.g. displaying the results in alphabetic order) each <OrderedObject>shall implement the IOrderedObjectType Interface, providing the order by a specific Property(see definition of IOrderedObjectType).
The NodeVersionis intended to be used in conjunction with the GeneralModelChangeEventTypein the way defined in OPC 10000-3. The NodeVersion should be provided if the ordered List can change (e.g. new Objectsadded or removed). This allows Clientsto subscribe to the Propertyor the GeneralModelChangeEvents, instead of polling Browse calls. Changes in the order of the List are considered as adding and deleting References, i.e. if the order changes the NodeVersionshall be changed and a GeneralModelChangeEventshall be issued, indicating that Referenceshave been added and deleted.
In Table 65the additional Referencesare defined.
Table 65– OrderedListType Additional Subcomponents
SourcePath |
References |
NodeClass |
BrowseName |
DataType |
TypeDefinition |
Other |
<OrderedObject> |
HasProperty |
Variable |
NumberInList |
Number |
PropertyType |
M |
<OrderedObject> |
HasInterface |
ObjectType |
IOrderedObjectType |
|
|
|
The <OrderedObject> Objectshall implement the Interface IOrderedObjectTypeand therefore contains the mandatory Property NumberInList.