BrowseServers Method (EasyAEClientCore)

Browses the specified computer and returns information about OPC (Alarms and Events) servers found.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Public Function BrowseServers( _
   ByVal location As String, _
   ByVal technologies As OpcTechnologies _
) As ServerElementCollection

'Usage
 
Dim instance As EasyAEClientCore
Dim location As String
Dim technologies As OpcTechnologies
Dim value As ServerElementCollection
 
value = instance.BrowseServers(location, technologies)

public ServerElementCollection BrowseServers( 
   string location,
   OpcTechnologies technologies
)

public:
ServerElementCollection^ BrowseServers( 
   String^ location,
   OpcTechnologies technologies
)

Parameters

location

Name of the machine. Determines the computer to browse for OPC servers. It may be an empty string, in which case the local computer will be browsed.

The value represents a UNC or DNS computer name. 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. IPv6 addresses are normally enclosed between '[' and ']'.

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

technologies

The OPC technologies to be used for server browsing.

Return Value

The method returns a keyed collection of OpcLabs.EasyOpc.ServerElement values, each containing information about a particular OPC server found on the specified machine. The keys of the keyed collection are the server's CLSIDs.

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.OperationModel.OpcException	The OPC "Classic" (or OPC XML-DA) 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.OperationModel.OpcException

The OPC "Classic" (or OPC XML-DA) 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.

Example

CSharp
VB.NET
Python

// This example shows how to obtain all ProgIDs of all OPC Alarms and Events servers on the local machine.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

using System;
using System.Diagnostics;
using OpcLabs.EasyOpc;
using OpcLabs.EasyOpc.AlarmsAndEvents;
using OpcLabs.EasyOpc.OperationModel;

namespace DocExamples.AlarmsAndEvents._EasyAEClient
{
    class BrowseServers 
    { 
        public static void Main1()
        {
            // Instantiate the client object.
            var client = new EasyAEClient();

            ServerElementCollection serverElements;
            try
            {
                serverElements = client.BrowseServers("");
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            foreach (ServerElement serverElement in serverElements)
            {
                Debug.Assert(serverElement != null);
                Console.WriteLine("serverElements[\"{0}\"].ProgId: {1}", serverElement.Clsid, serverElement.ProgId);
            }
        }
    } 
}

' This example shows how to obtain all ProgIDs of all OPC Alarms and Events servers on the local machine.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET .
' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
' a commercial license in order to use Online Forums, and we reply to every post.

Imports OpcLabs.EasyOpc
Imports OpcLabs.EasyOpc.AlarmsAndEvents
Imports OpcLabs.EasyOpc.OperationModel

Namespace AlarmsAndEvents._EasyAEClient

    Friend Class BrowseServers
        Public Shared Sub Main1()
            Dim client = New EasyAEClient()

            Dim serverElements As ServerElementCollection
            Try
                serverElements = client.BrowseServers("")
            Catch opcException As OpcException
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
                Exit Sub
            End Try

            For Each serverElement As ServerElement In serverElements
                Debug.Assert(serverElement IsNot Nothing)
                Console.WriteLine("serverElements[""{0}""].ProgId: {1}", serverElement.Clsid, serverElement.ProgId)
            Next serverElement
        End Sub
    End Class

End Namespace

# This example shows how to obtain all ProgIDs of all OPC Data Access servers on the local machine.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
# a commercial license in order to use Online Forums, and we reply to every post.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

# Import .NET namespaces.
from OpcLabs.EasyOpc.DataAccess import *
from OpcLabs.EasyOpc.OperationModel import *


# Instantiate the client object
client = EasyDAClient()

# Perform the operation
try:
    serverElements = IEasyDAClientExtension.BrowseServers(client, '')
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

# Display results
for serverElement in serverElements:
    print('ServerElements("' + serverElement.ClsidString + '"): ' + serverElement.ProgId)

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

EasyAEClientCore Class
EasyAEClientCore Members

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