DiscoverLocalApplications(IEasyUAClient,String,UAApplicationTypes) Method

Discovers OPC-UA applications available on the discovery host, specifying the discovery host, and application types.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function DiscoverLocalApplications( _
   ByVal client As IEasyUAClient, _
   ByVal discoveryHost As String, _
   ByVal applicationTypes As UAApplicationTypes _
) As UADiscoveryElementCollection

'Usage
 
Dim client As IEasyUAClient
Dim discoveryHost As String
Dim applicationTypes As UAApplicationTypes
Dim value As UADiscoveryElementCollection
 
value = IEasyUAClientExtension.DiscoverLocalApplications(client, discoveryHost, applicationTypes)

[Extension()]
[NotNull()]
public static UADiscoveryElementCollection DiscoverLocalApplications( 
   IEasyUAClient client,
   string discoveryHost,
   UAApplicationTypes applicationTypes
)

[Extension()]
[NotNull()]
public:
static UADiscoveryElementCollection^ DiscoverLocalApplications( 
   IEasyUAClient^ client,
   String^ discoveryHost,
   UAApplicationTypes applicationTypes
)

Parameters

client

The client object that will perform the operation.

This is typically the EasyUAClient object.

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

discoveryHost

The name of the machine that runs the discovery server that will be used for discovery task.

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

applicationTypes

Application types to be discovered.

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 discovers available OPC-UA applications and returns information about them, using the specified discovery host, and filtering by specified application types. It uses the so-called Local Discovery Server (LDS). You can influence how the discovery works using the properties in static SharedParameters.

Invokes the FindServers service.

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

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

IEasyUAClientExtension Class
IEasyUAClientExtension Members
Overload List

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