The ServerCapabilitiesType Objectsfor any OPC UA Serversupporting Historical Access shall contain a Referenceto a HistoryServerCapabilitiesType Object.

The content of this BaseObjectTypeis already defined by its type definition in OPC 10000-5. The Object extensions are formally defined in Table 8.

These properties are intended to inform a Clientof the general capabilities of the Server. They do not guarantee that all capabilities will be available for all Nodes. For example not all Nodeswill support Events, or in the case of an aggregating Serverwhere underlying Serversmay not support Insertor a particular Aggregate. In such cases the HistoryServerCapabilities Propertywould indicate the capability is supported, and the Serverwould return appropriate StatusCodesfor situations where the capability does not apply.

Table 8– HistoryServerCapabilitiesType Definition

Attribute

Value

BrowseName

HistoryServerCapabilitiesType

IsAbstract

False

References

NodeClass

Browse Name

Data Type

Type Definition

ModelingRule

HasProperty

Variable

AccessHistoryDataCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

AccessHistoryEventsCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

MaxReturnDataValues

UInt32

PropertyType

Mandatory

HasProperty

Variable

MaxReturnEventValues

UInt32

PropertyType

Mandatory

HasProperty

Variable

InsertDataCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

ReplaceDataCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

UpdateDataCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

DeleteRawCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

DeleteAtTimeCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

InsertEventCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

ReplaceEventCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

UpdateEventCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

DeleteEventCapability

Boolean

PropertyType

Mandatory

HasProperty

Variable

InsertAnnotationCapability

Boolean

PropertyType

Mandatory

HasComponent

Object

AggregateFunctions

--

FolderType

Mandatory

HasProperty

Variable

ServerTimestampSupported

Boolean

PropertyType

Optional

All UA Serversthat support Historical Access shall include the HistoryServerCapabilitiesas part of its ServerCapabilities.

The AccessHistoryDataCapability Variabledefines if the Serversupports access to historical data values. A value of True indicates the Serversupports access to the history for HistoricalNodes, a value of False indicates the Serverdoes not support access to the history for HistoricalNodes. The default value is False. At least one of AccessHistoryDataCapabilityor AccessHistoryEventsCapabilityshall have a value of True for the Serverto be a valid OPC UA Serversupporting Historical Access.

The AccessHistoryEventCapability Variabledefines if the server supports access to historical Events. A value of True indicates the server supports access to the history ofEvents, a value of False indicates the Serverdoes not support access to the history of Events. The default value is False. At least one of AccessHistoryDataCapabilityor AccessHistoryEventsCapabilityshall have a value of True for the Serverto be a valid OPC UA Serversupporting Historical Access.

The MaxReturnDataValues Variabledefines the maximum number of values that can be returned by the Serverfor each HistoricalNodeaccessed during a request. A value of 0 indicates that the Serverforces no limit on the number of values it can return. It is valid for a Serverto limit the number of returned values and return a continuation point even if MaxReturnValues= 0. For example, it is possible that although the Serverdoes not impose any restrictions, the underlying system may impose a limit that the Serveris not aware of. The default value is 0.

Similarily, the MaxReturnEventValuesspecifies the maximum number of Eventsthat a Servercan return for a HistoricalEventNode.

The InsertDataCapability Variableindicates support for the Insert capability. A value of True indicates the Serversupports the capability to insert new data values in history, but not overwrite existing values. The default value is False.

The ReplaceDataCapability Variableindicates support for the Replace capability. A value of True indicates the Serversupports the capability to replace existing data values in history, but will not insert new values. The default value is False.

The UpdateDataCapability Variableindicates support for the Update capability. A value of True indicates the Serversupports the capability to insert new data values into history if none exists, and replace values that currently exist. The default value is False.

The DeleteRawCapability Variableindicates support for the delete raw values capability. A value of True indicates the Serversupports the capability to delete raw datavalues in history. The default value is False.

The DeleteAtTimeCapability Variableindicates support for the delete at time capability. A value of True indicates the Serversupports the capability to delete a data value at a specified time. The default value is False.

The InsertEventCapability Variableindicates support for the Insert capability. A value of True indicates the Serversupports the capability to insert new Eventsin history. An insert is not a replace. The default value is False.

The ReplaceEventCapability Variableindicates support for the Replace capability. A value of True indicates the Serversupports the capability to replace existing Events in history. A replace is not an insert. The default value is False.

The UpdateEventCapability Variableindicates support for the Update capability. A value of True indicates the Serversupports the capability to insert new Eventsinto history if none exists, and replace values that currently exist. The default value is False.

The DeleteEventCapability Variableindicates support for the deletion of Eventscapability. A value of True indicates the Serversupports the capability to delete Eventsin history. The default value is False.

The InsertAnnotationCapability Variableindicates support for Annotations. A value of True indicates the Serversupports the capability to insertAnnotations. Some Serversthat support Inserting of Annotationswill also support editing and deleting of Annotations. The default value is False.

AggregateFunctions is an entry point to browse to all Aggregatecapabilities supported by the Serverfor Historical Access. All HistoryAggregates supported by the Servershould be able to be browsed starting from this Object. Aggregatesare defined inOPC 10000-13. If the Serverdoes not support Aggregatesthe Folderis left empty.

The ServerTimestampSupported Variableindicates support for the ServerTimestampcapability. A value of True indicates the Serversupports ServerTimestampsin addition to SourceTimestamp. The default is False. This property is optional but it is expected all new Serversinclude this property.