The sixth example provides an illustration a different type of request, one in which the Client is interested in displaying part of the AddressSpace of the Server. This request includes listing a Reference as something that is to be returned.

Example 6: Get PersonType.NodeId, AnimalType.NodeId, PersonType.HasChild Reference, PersonType.HasAnimal Reference where a person has a child who has a Animal.

Table B.18 describes the NodeTypeDescription parameters used in the example.

Table B.18 – Example 6 NodeTypeDescription

Type Definition Node

Include

Subtypes

QueryDataDescription

Relative Path

Attribute

Index Range

PersonType

FALSE

“.12:NodeId”

value

N/A

<12:HasChild>12:PersonType<12:HasAnimal>12:AnimalType.NodeId

value

N/A

<12:HasChild>

value

N/A

<12:HasChild>12:PersonType<12:HasAnimal>

value

N/A

The corresponding ContentFilter is illustrated in Figure B.10.

image052.png

Figure B.10 – Example 6 filter logic tree

Table B.19 describes the elements, operators and operands used in the example.

Table B.19 – Example 6 ContentFilter

Element[]

Operator

Operand[0]

Operand[1]

Operand[2]

Operand[3]

0

RelatedTo

AttributeOperand = NodeId: 12:PersonType, BrowsePath “.”, Attribute: NodeId

ElementOperand = 1

AttributeOperand = Node: 12:HasChild, BrowsePath “.”,Attribute:NodeId

LiteralOperand = ‘1’

1

RelatedTo

AttributeOperand = NodeId: 12:PersonType, BrowsePath “.”, Attribute: NodeId

AttributeOperand = NodeId: 12:AnimalType, BrowsePath “.”, Attribute: NodeId

AttributeOperand = NodeId: 12:HasAnimal, BrowsePath “.”, Attribute: NodeId

LiteralOperand = ‘1’

The results from this query would contain the QueryDataSets shown in Table B.20.

Table B.20 – Example 6 QueryDataSets

NodeId

TypeDefinition

NodeId

RelativePath

Value

12:42 (HFamily1)

PersonType

“.NodeId”

12:42 (HFamily1)

<12:HasChild>12:PersonType<12:HasAnimal>

12:AnimalType.NodeId

12:91 (Pig1)

<12:HasChild>

HasChild

ReferenceDescription

<12:HasChild>12:PersonType<12:HasAnimal>

HasFarmAnimal

ReferenceDescription

12:48 (HFamily2)

PersonType

“.NodeId”

12:48 (HFamily2)

<12:HasChild>12:PersonType<12:HasAnimal>

12:AnimalType.NodeId

12:91 (Pig1)

<12:HasChild>

HasChild

ReferenceDescription

<12:HasChild>12:PersonType<12:HasAnimal>

HasPet

ReferenceDescription

NOTE The RelativePath and browse name (in parentheses) is not in the QueryDataSet and is only shown here for clarity and the TypeDefinition NodeId would be an integer, not the symbolic name that is included in the table. The value field would in this case be the NodeId where it was requested, but for the example the browse name is provided in parentheses and in the case of Reference types on the browse name is provided. For the References listed in Table B.20, the value would be a ReferenceDescription which are described in 7.30.

Table B.21 provides an example of the same QueryDataSet as shown in Table B.20 without any additional fields and minimal symbolic Ids. There is an entry for each requested Attribute, in the cases where an Attribute would return multiple entries the entries are separated by comas. If a structure is being returned then the structure is enclosed in square brackets. In the case of a ReferenceDescription the structure contains a structure and DisplayName and BrowseName are assumed to be the same and defined in Figure B.4.

Table B.21 – Example 6 QueryDataSets without additional information

NodeId

TypeDefinition

NodeId

Value

12:42

PersonType

12:42

12:91

[HasChild,TRUE,[48,HFamily2,HFamily2,PersonType]],

[HasFarmAnimal,TRUE[91,Pig1,Pig1,PigType]

12:48

PersonType

12:54

12:91

[HasChild,TRUE,[ 54,HFamily3,HFamily3,PersonType]]

[HasPet, TRUE,[ 91,Pig1,Pig1,PigType]]

The PersonType, HasChild, PigType, HasPet, HasFarmAnimal identifiers used in the above table would be translated to actual ExpandedNodeId.