DiscoverGlobalApplications Method (

Globally discovers OPC-UA applications, specifying the GDS endpoint, and query applications filter.

Globally discovers OPC-UA applications, using the specified GDS endpoint.

This method globally discovers OPC-UA applications that meet the specified filters and returns information about them, using the specified GDS endpoint.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<NotNullAttribute()>
Function DiscoverGlobalApplications( _
   ByVal gdsEndpointDescriptorString As String, _
   ByVal queryApplicationsFilter As Object _
) As UADiscoveryElementCollection

'Usage
 
Dim instance As _EasyUAClient
Dim gdsEndpointDescriptorString As String
Dim queryApplicationsFilter As Object
Dim value As UADiscoveryElementCollection
 
value = instance.DiscoverGlobalApplications(gdsEndpointDescriptorString, queryApplicationsFilter)

[NotNull()]
UADiscoveryElementCollection DiscoverGlobalApplications( 
   string gdsEndpointDescriptorString,
   object queryApplicationsFilter
)

[NotNull()]
UADiscoveryElementCollection^ DiscoverGlobalApplications( 
   String^ gdsEndpointDescriptorString,
   Object^ queryApplicationsFilter
)

Parameters

gdsEndpointDescriptorString

The value represents an OPC UA endpoint descriptor string. Any string can be passed to this parameter (i.e. will not cause System.ArgumentException), but not all values make sense and will work when an operation using them is attempted. The OPC UA endpoint descriptor string is typically the URL of the server endpoint.

The value of this parameter can be null (Nothing in Visual Basic).

queryApplicationsFilter

A filter used to find servers that meet the specified criteria.

The value of this parameter cannot be null (Nothing in Visual Basic).

Return Value

Returns a collection of application elements (servers, OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement).

This method never returns null (Nothing in Visual Basic).

The individual elements of the returned value are never null (Nothing in Visual Basic).

Exceptions

Exception Description

Exception	Description
System.ArgumentNullException	A `null` reference (`Nothing` in Visual Basic) is passed to a method that does not accept it as a valid argument. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.
OpcLabs.EasyOpc.UA.OperationModel.UAException	The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause. This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

System.ArgumentNullException

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

OpcLabs.EasyOpc.UA.OperationModel.UAException

The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

Remarks

This method globally discovers OPC-UA applications that meet the specified filters and returns information about them, using the specified GDS endpoint.

This method uses the so-called OPC UA Global Discovery Server (GDS).

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

This member or type is for use from COM. It is not meant to be used from .NET or Python. Refer to the corresponding .NET member or type instead, if you are developing in .NET or Python.

This is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

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

_EasyUAClient Interface
_EasyUAClient Members

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