.NET Based OPC UA Client/Server SDK  2.6.1.422
UnifiedAutomation.UaBase.QueryFirstRequest Class Reference

Asynchronously queries the address space. More...

Inherits UnifiedAutomation.UaBase.IServiceRequest, and UnifiedAutomation.UaBase.IEncodeable.

Public Member Functions

 QueryFirstRequest ()
 The default constructor. More...
 
virtual void Encode (IEncoder encoder)
 
virtual void Decode (IDecoder decoder)
 
virtual bool IsEqual (IEncodeable encodeable)
 Checks if encodeable is the same object or has the same content More...
 
virtual object Clone ()
 

Properties

RequestHeader RequestHeader [get, set]
 
ViewDescription View [get, set]
 Specifies a view and temporal context to a Server. More...
 
NodeTypeDescriptionCollection NodeTypes [get, set]
 The node type description. More...
 
ContentFilter Filter [get, set]
 Resulting nodes shall be limited to the nodes matching the criteria defined by the filter. More...
 
uint MaxDataSetsToReturn [get, set]
 The number of QueryDataSets that the Client wants the Server to return in the response and on each subsequent continuation call response. More...
 
uint MaxReferencesToReturn [get, set]
 The number of references that the Client wants the Server to return in the response for each QueryDataSet and on each subsequent continuation call response. More...
 
virtual ExpandedNodeId TypeId [get]
 
virtual ExpandedNodeId BinaryEncodingId [get]
 
virtual ExpandedNodeId XmlEncodingId [get]
 
- Properties inherited from UnifiedAutomation.UaBase.IServiceRequest
RequestHeader RequestHeader [get, set]
 The header for the request. More...
 
- Properties inherited from UnifiedAutomation.UaBase.IEncodeable
ExpandedNodeId TypeId [get]
 Returns the UA type identifier for the encodable type. More...
 
ExpandedNodeId BinaryEncodingId [get]
 Returns the UA type identifier for the default binary encoding for the type. More...
 
ExpandedNodeId XmlEncodingId [get]
 Returns the UA type identifier for the default XML encoding for the type. More...
 

Detailed Description

Asynchronously queries the address space.

This Service is used to issue a query request to the Server. The complexity of the query can range from very simple to highly sophisticated. The query can simply request data from instances of a TypeDefinitionNode or TypeDefinitionNode subject to restrictions specified by the filter. On the other hand, the query can request data from instances of related node types by specifying a RelativePath from an originating TypeDefinitionNode.In the filter, a separate set of paths can be constructed for limiting the instances that supply data. A filtering path can include multiple RelatedTo operators to define a multi-hop path between source instances and target instances.

The Client provides an array of NodeTypeDescription which specify the NodeId of a TypeDefinitionNode and selects what attributes are to be returned in the response. A client can also provide a set of RelativePaths through the type system starting from an originating TypeDefinitionNode. Using these paths, the client selects a set of attributes from nodes that are related to instances of the originating TypeDefinitionNode. Additionally, the Client can request the Server return instances of subtypes of TypeDefinitionNodes. If a selected Attribute does not exist in a TypeDefinitionNode but does exist in a subtype, it is assumed to have a null value in the TypeDefinitionNode in question. Therefore, this does not constitute an error condition and a null value is returned for the Attribute.

The Client can use the filter parameter to limit the result set by restricting attributes and properties to certain values. Another way the Client can use a filter to limit the result set is by specifying how instances should be related, using RelatedTo operators. In this case, if an instance at the top of the RelatedTo path cannot be followed to the bottom of the path via specified hops, no QueryDataSets are returned for the starting instance or any of the intermediate instances.

When querying for related instances in the RelativePath, the Client can optionally ask for references. A reference is requested via a RelativePath that only includes a ReferenceType. If all references are desired than the root ReferenceType is listed. These references are returned as part of the QueryDataSets.

Query services allow a special handling of the targetName field in the RelativePath. In several query use cases, a type NodeId is necessary in the path instead of a QualifiedName. Therefore, the Client is allowed to specify a NodeId in the QualifiedName. This is done by setting the namespaceIndex of the targetName to zero and the name part of the targetName to the XML representation of the NodeId. When matching instances are returned as the target node, the target node shall be an instance of the specified type or subtype of the specified type.

Constructor & Destructor Documentation

UnifiedAutomation.UaBase.QueryFirstRequest.QueryFirstRequest ( )
inline

The default constructor.

Member Function Documentation

virtual bool UnifiedAutomation.UaBase.QueryFirstRequest.IsEqual ( IEncodeable  encodeable)
inlinevirtual

Checks if encodeable is the same object or has the same content

Parameters
encodeable
Returns

Implements UnifiedAutomation.UaBase.IEncodeable.

Property Documentation

ContentFilter UnifiedAutomation.UaBase.QueryFirstRequest.Filter
getset

Resulting nodes shall be limited to the nodes matching the criteria defined by the filter.

Resulting nodes shall be limited to the nodes matching the criteria defined by the filter.

uint UnifiedAutomation.UaBase.QueryFirstRequest.MaxDataSetsToReturn
getset

The number of QueryDataSets that the Client wants the Server to return in the response and on each subsequent continuation call response.

The Server is allowed to further limit the response, but shall not exceed this limit. A value of 0 indicates that the Client is imposing no limitation.

uint UnifiedAutomation.UaBase.QueryFirstRequest.MaxReferencesToReturn
getset

The number of references that the Client wants the Server to return in the response for each QueryDataSet and on each subsequent continuation call response.

The Server is allowed to further limit the response, but shall not exceed this limit.

A value of 0 indicates that the Client is imposing no limitation.

For example: In a result, 4 Nodes are being returned, but each has 100 References. If this limit was set to 50, only the first 50 References for each Node would be returned on the initial call, and a continuation point would be set indicating additional data.

NodeTypeDescriptionCollection UnifiedAutomation.UaBase.QueryFirstRequest.NodeTypes
getset

The node type description.

RequestHeader UnifiedAutomation.UaBase.QueryFirstRequest.RequestHeader
getset

ViewDescription UnifiedAutomation.UaBase.QueryFirstRequest.View
getset

Specifies a view and temporal context to a Server.


The documentation for this class was generated from the following file: