QuerySourceConditions Method (IEasyAEClientExtension)

Finds out event conditions associated with the specified source name. Computer name and server class are used for specifying the OPC server.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Shared Function QuerySourceConditions( _
   ByVal client As IEasyAEClient, _
   ByVal machineName As String, _
   ByVal serverClass As String, _
   ByVal sourceNodeDescriptor As AENodeDescriptor _
) As AEConditionElementCollection

'Usage
 
Dim client As IEasyAEClient
Dim machineName As String
Dim serverClass As String
Dim sourceNodeDescriptor As AENodeDescriptor
Dim value As AEConditionElementCollection
 
value = IEasyAEClientExtension.QuerySourceConditions(client, machineName, serverClass, sourceNodeDescriptor)

[Extension()]
[NotNull()]
public static AEConditionElementCollection QuerySourceConditions( 
   IEasyAEClient client,
   string machineName,
   string serverClass,
   AENodeDescriptor sourceNodeDescriptor
)

[Extension()]
[NotNull()]
public:
static AEConditionElementCollection^ QuerySourceConditions( 
   IEasyAEClient^ client,
   String^ machineName,
   String^ serverClass,
   AENodeDescriptor^ sourceNodeDescriptor
)

Parameters

client

The client object that will perform the operation.

This is typically the EasyAEClient object.

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

machineName

Name of the machine. Determines the computer on which the OPC server is located. It may be an empty string, in which case the OPC server is assumed to exist on the local computer or at the computer specified for it by DCOM configuration.

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).

serverClass

Contains ProgID of the OPC server.

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

sourceNodeDescriptor

A source node descriptor, usually expressed as qualified source name. Only the conditions associated with this source are returned.

Because the AENodeDescriptor has an implicit conversion from System.String and OpcLabs.EasyOpc.AlarmsAndEvents.AddressSpace.AENodeElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the qualified name of the node), or a OpcLabs.EasyOpc.AlarmsAndEvents.AddressSpace.AENodeElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC A&E node descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the FromString or FromAENodeElement static method instead.

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

Return Value

A collection of condition elements, one element for each condition of the given source.

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.ArgumentException	One of the arguments provided to a method is not valid. 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.
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.ArgumentException

One of the arguments provided to a method is not valid.

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.

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.

Remarks

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

IEasyAEClientExtension Class
IEasyAEClientExtension Members

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