<EventFilter>

The <EventFilter> </EventFilter> elements define which events associated with a monitored item result in the server generating a notification.

The <EventFilter> and </EventFilter> elements contain the following child elements:

<SelectClauses> </SelectClauses>

Contain one or more <SimpleAttributeOperand> and </SimpleAttributeOperand> elements, each of which defines the values to include in a notification. See <SimpleAttributeOperand>.

<WhereClauses> </WhereClauses>

Contain the <Elements> and </Elements> elements which in turn contain the <ContentFilterElement> and </ContentFilterElement> elements. That element limits the events that can cause the generation of a notification to those that meet conditions that the element's contents define. See <ContentFilterElement>.

<SimpleAttributeOperand>

The <SimpleAttributeOperand> and </SimpleAttributeOperand> elements define a value to include in each notification that the OPC UA server generates for this monitored item. This value is an attribute of the monitored item.

The <SimpleAttributeOperand> and </SimpleAttributeOperand> elements contain the following child elements:

<TypeDefinitionId> </TypeDefinitionId>

Define the type of the attribute. For example, a value of i=2041 indicates that this is a base event type.

<BrowsePath> </BrowsePath>

Specify the relative path to the node. This element contains one <QualifiedName> and </QualifiedName> element pair that define the path. See <QualifiedName>.

<AttributeId>

</AttributeId>

Specify the identifier of the attribute to include in a notification. The OPC UA standard defines the attribute identifiers. For example, a value of 13 selects the value of an item.

Note: The value 13 indicates a string data type.

<QualifiedName>

The <QualifiedName> and </QualifiedName> elements contain the relative path to the node as a qualified name.

The <QualifiedName> and </QualifiedName> elements contain the following child elements:

<NamespaceIndex> </NamespaceIndex>

Specify an index for the namespace URI that includes the node. Use a value of 0 for the node identifiers defined in the OPC UA standard.

<Name> </Name>

Specify the name of the node.

<ContentFilterElement>

The <ContentFilterElement> and </ContentFilterElement> elements define conditions that limit the events that can cause the server to generate a notification.

The <ContentFilterElement> and </ContentFilterElement> elements contain the following child elements:

<FilterOperator> </FilterOperator>

Specify the operator to use in the filter. This determines the number of operands required.

<FilterOperands> </FilterOperands>

Specify the definition of an operand for the expression defined by the operator. The type of operator defines the number of operands required. For example, the NOT operator requires one operand only, whereas the Equals operator requires two operands.

This element can contain an <ExtensionObject> element. See <ExtensionObject>.

<ExtensionObject>

The <ExtensionObject> and </ExtensionObject> elements define an application specific data type that may not be recognized by the receiver.