UALocalApplicationDiscoveryQuery Class

An OPC UA discovery query for applications on the specified discovery host or discovery endpoints.

Object Model

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<CLSCompliantAttribute(True)>
<ComDefaultInterfaceAttribute(OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALocalApplicationDiscoveryQuery)>
<ComVisibleAttribute(True)>
<GuidAttribute("54CC01A8-15CD-4BEA-8FD9-F7D950EC7A43")>
<TypeConverterAttribute(System.ComponentModel.ExpandableObjectConverter)>
<ValueControlAttribute("OpcLabs.BaseLib.Forms.Common.ObjectSerializationControl, OpcLabs.BaseLibForms, Version=5.80.82.1, Culture=neutral, PublicKeyToken=6faddca41dacb409", 
   DefaultReadWrite=False, 
   Export=True, 
   PageId=10001)>
<SerializableAttribute()>
Public NotInheritable Class UALocalApplicationDiscoveryQuery 
   Inherits UALdsDiscoveryQuery
   Implements LINQPad.ICustomMemberProvider, OpcLabs.BaseLib.ComTypes._Info, OpcLabs.BaseLib.ComTypes._Object2, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UAApplicationDiscoveryQuery, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALdsDiscoveryQuery, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALocalApplicationDiscoveryQuery, System.ICloneable, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable

'Usage
 
Dim instance As UALocalApplicationDiscoveryQuery

[CLSCompliant(true)]
[ComDefaultInterface(OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALocalApplicationDiscoveryQuery)]
[ComVisible(true)]
[Guid("54CC01A8-15CD-4BEA-8FD9-F7D950EC7A43")]
[TypeConverter(System.ComponentModel.ExpandableObjectConverter)]
[ValueControl("OpcLabs.BaseLib.Forms.Common.ObjectSerializationControl, OpcLabs.BaseLibForms, Version=5.80.82.1, Culture=neutral, PublicKeyToken=6faddca41dacb409", 
   DefaultReadWrite=false, 
   Export=true, 
   PageId=10001)]
[Serializable()]
public sealed class UALocalApplicationDiscoveryQuery : UALdsDiscoveryQuery, LINQPad.ICustomMemberProvider, OpcLabs.BaseLib.ComTypes._Info, OpcLabs.BaseLib.ComTypes._Object2, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UAApplicationDiscoveryQuery, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALdsDiscoveryQuery, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALocalApplicationDiscoveryQuery, System.ICloneable, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable

[CLSCompliant(true)]
[ComDefaultInterface(OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALocalApplicationDiscoveryQuery)]
[ComVisible(true)]
[Guid("54CC01A8-15CD-4BEA-8FD9-F7D950EC7A43")]
[TypeConverter(System.ComponentModel.ExpandableObjectConverter)]
[ValueControl("OpcLabs.BaseLib.Forms.Common.ObjectSerializationControl, OpcLabs.BaseLibForms, Version=5.80.82.1, Culture=neutral, PublicKeyToken=6faddca41dacb409", 
   DefaultReadWrite=false, 
   Export=true, 
   PageId=10001)]
[Serializable()]
public ref class UALocalApplicationDiscoveryQuery sealed : public UALdsDiscoveryQuery, LINQPad.ICustomMemberProvider, OpcLabs.BaseLib.ComTypes._Info, OpcLabs.BaseLib.ComTypes._Object2, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UAApplicationDiscoveryQuery, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALdsDiscoveryQuery, OpcLabs.EasyOpc.UA.Discovery.ComTypes._UALocalApplicationDiscoveryQuery, System.ICloneable, System.Runtime.Serialization.ISerializable, System.Xml.Serialization.IXmlSerializable

Remarks

The query is performed using a FindServers service on the specified discovery URIs.

See also in Knowledge Base: Technical note-OPC UA Discovery in QuickOPC.

The various kinds of OPC UA discovery can be generalized into just one method, Discover. This method is given a discovery query argument (of UADiscoveryQuery type) that tells it the requirements for the discovery. The specific kinds of OPC UA discovery described earlier are, in fact, implemented by constructing the discovery query appropriately, and then calling the Discover method.

The UADiscoveryQuery type is an abstract class which is at the root of a structured class hierarchy, with several concrete subclasses:

UAGlobalApplicationDiscoveryQuery is for searching the applications globally in the administrative domain. With this query, you need to specify the GDS endpoint, and optionally a filter (UAQueryServerFilter), used to find servers that meet the specified criteria.
UALocalApplicationDiscoveryQuery is used when you know the LDS endpoints, and want to perform discovery on these endpoints (usually in parallel). This is a specialized kind of local discovery.
UALocalApplicationDiscoveryQuery is for finding applications local to a specified host.
UANetworkServerDiscoveryQuery is for finding servers on a multicast subnet (or more connected subnets) using LDS-ME (Local Discovery Server with Multicast Extensions).

This generalized discovery mechanism allows for flexibility both on the component and developer sides, and possible future expansion with other kinds of discovery, without a need to introduce new methods into the IEasyUAClient interface.

Inheritance Hierarchy

System.Object
   OpcLabs.BaseLib.Object2
      OpcLabs.BaseLib.Info
         OpcLabs.EasyOpc.UA.Discovery.UADiscoveryQuery
            OpcLabs.EasyOpc.UA.Discovery.UAApplicationDiscoveryQuery
               OpcLabs.EasyOpc.UA.Discovery.UALdsDiscoveryQuery
                  OpcLabs.EasyOpc.UA.Discovery.UALocalApplicationDiscoveryQuery

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

Reference

UALocalApplicationDiscoveryQuery Members
OpcLabs.EasyOpc.UA.Discovery Namespace

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