BrowseServers(IEasyDAClient,String) Method

Browses the specified computer and returns information about OPC (Data Access) servers found.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function BrowseServers( _
   ByVal client As IEasyDAClient, _
   ByVal location As String _
) As ServerElementCollection

'Usage
 
Dim client As IEasyDAClient
Dim location As String
Dim value As ServerElementCollection
 
value = IEasyDAClientExtension.BrowseServers(client, location)

[Extension()]
[ElementsNotNull()]
[NotNull()]
public static ServerElementCollection BrowseServers( 
   IEasyDAClient client,
   string location
)

[Extension()]
[ElementsNotNull()]
[NotNull()]
public:
static ServerElementCollection^ BrowseServers( 
   IEasyDAClient^ client,
   String^ location
)

Parameters

client: The client object that will perform the operation.
location: Name of the machine. Determines the computer to browse for OPC servers. May be an empty string, in which case the local computer will be browsed.

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.

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

.NET

// This example shows how to obtain all ProgIDs of all OPC Data Access servers on the local machine.

using System;
using OpcLabs.EasyOpc;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.OperationModel;

namespace DocExamples.DataAccess._EasyDAClient
{
    class BrowseServers
    {
        public static void Main1()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();
            ServerElementCollection serverElements;
            try
            {
                serverElements = client.BrowseServers("");
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            foreach (ServerElement serverElement in serverElements)
                Console.WriteLine($"ServerElements(\"{serverElement.ClsidString}\").ProgId: {serverElement.ProgId}");
        }


        // Example output:
        //
        //ServerElements("c8a12f17-1e03-401e-b53d-6c654dd576da").ProgId: OPCLabs.KitServer.2
    }
}

# This example shows how to obtain all ProgIDs of all OPC Data Access servers on the local machine.

# 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)

JScript
PHP
Python
VBScript

// This example shows how to obtain all ProgIDs of all OPC Data Access servers on the local machine.

var Client = new ActiveXObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient");
var ServerElements = Client.BrowseServers("")

for (var objEnum = new Enumerator(ServerElements) ; !objEnum.atEnd() ; objEnum.moveNext()) {
    var ServerElement = objEnum.item();
    WScript.Echo("ServerElements(\"" + ServerElement.UrlString + "\").ProgId: " + ServerElement.ProgId);
}

// This example shows how to obtain all ProgIDs of all OPC Data Access servers on the local machine.

$Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient");

try
{
    $ServerElements = $Client->BrowseServers("");
}
catch (com_exception $e)
{
    printf("*** Failure: %s\n", $e->getMessage());
    Exit();
}

foreach ($ServerElements as $ServerElement)
{
    printf("ServerElements(\"s\").ProgIds\n", $ServerElement->ClsidString, $ServerElement->ProgId);
}

# This example shows how to obtain all ProgIDs of all OPC Data Access servers on the local machine.

# The Python for Windows (pywin32) extensions package is needed. Install it using "pip install pypiwin32".
# CAUTION: We now recommend using Python.NET package instead. Full set of examples with Python.NET is available!
import win32com.client
from pywintypes import com_error

# Instantiate the client object
client = win32com.client.Dispatch('OpcLabs.EasyOpc.DataAccess.EasyDAClient') 

# Perform the operation
try:
    serverElements = client.BrowseServers('')
except com_error as e:
    print('*** Failure: ' + e.args[2][1] + ': ' + e.args[2][2])
    exit()

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

Rem This example shows how to obtain all ProgIDs of all OPC Data Access servers on the local machine.

Option Explicit

Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
On Error Resume Next
Dim ServerElements: Set ServerElements = Client.BrowseServers("")
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

Dim ServerElement: For Each ServerElement In ServerElements
    WScript.Echo "ServerElements(""" & ServerElement.ClsidString & """).ProgId: " & ServerElement.ProgId
Next

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

IEasyDAClientExtension Class
IEasyDAClientExtension Members
Overload List

Send Documentation Feedback. Resources: Knowledge Base. Technical support: Online Forums, FAQ.