SWbemObject.InstancesAsync_ method

Article
01/07/2021

The InstancesAsync_ method of SWbemObject asynchronously supplies the instances of the current class object. This method implements a simple query. More complex queries may require the use of SWbemServices.ExecQuery.

For an explanation of this syntax, see Document Conventions for the Scripting API.

Syntax

SWbemObject.InstancesAsync_( _
  ByVal objWbemSink, _
  [ ByVal iFlags ], _
  [ ByVal objwbemNamedValueSet ], _
  [ ByVal objWbemAsyncContext ] _
)

Parameters

objWbemSink [in]: Object sink that returns the instances.
iFlags [in, optional]: Integer that determines the behavior of the call. This parameter can accept the following values.
wbemFlagSendStatus (128 (0x80)): Causes asynchronous calls to send status updates to the SWbemSink.OnProgress event handler for the object sink.
wbemFlagDontSendStatus (0 (0x0)): Prevents asynchronous calls from sending status updates to the OnProgress event handler for the object sink.
wbemFlagUseAmendedQualifiers (131072 (0x20000)): Causes WMI to return the localized class and property descriptions. For more information, see Localizing WMI Class Information.

objwbemNamedValueSet [in, optional]

Typically, this is undefined. Otherwise, this is an SWbemNamedValueSet object whose elements represent the context information that can be used by the provider that is servicing the request. A provider that supports or requires such information must document the recognized value names, data type of the value, allowed values, and semantics.

objWbemAsyncContext [in, optional]

This is an SWbemNamedValueSet object that returns to the object sink to identify the source of the original asynchronous call. Use this parameter if you are making multiple asynchronous calls using the same object sink. To use this parameter, create an SWbemNamedValueSet object and use the SWbemNamedValueSet.Add method to add a value that identifies the asynchronous call you are making. This SWbemNamedValueSet object is returned to the object sink and the source of the call can be extracted using the SWbemNamedValueSet.Item method. For more information, see Calling a Method.

Return value

This method does not return a value. If successful, the sink receives an OnObjectReady event per instance. After the last instance, the object sink will receive an OnCompleted event.

Error codes

After the completion of the InstancesAsync_ method, the Err object may contain one of the error codes in the following list.

wbemErrAccessDenied - 2147749891 (0x80041003): Current user does not have permission to view instances of the specified class.
wbemErrFailed - 2147749889 (0x80041001): Unspecified error occurred.
wbemErrInvalidClass - 2147749904 (0x80041010): Specified class is not valid.
wbemErrInvalidParameter - 2147749896 (0x80041008): A specified parameter is not valid.
wbemErrOutOfMemory - 2147749894 (0x80041006): Not enough memory to complete the operation.

Remarks

This call returns immediately. The requested objects and status are returned to the caller through callbacks delivered to the sink that is specified in objWbemSink. To process each object when it arrives, create an objWbemSink. OnObjectReady event subroutine. After all the objects are returned, you can perform final processing in your implementation of the objWbemSink. OnCompleted event.

An asynchronous callback allows a non-authenticated user to provide data to the sink. This poses security risks to your scripts and applications. To eliminate the risks, use either semisynchronous communication or synchronous communication. For more information, see Calling a Method.

The InstancesAsync_ method only works for class objects. It is not an error for the returned collection to have zero (0) elements.

Requirements

Requirement	Value
Minimum supported client	Windows Vista
Minimum supported server	Windows Server 2008
Header	Wbemdisp.h
Type library	Wbemdisp.tlb
DLL	Wbemdisp.dll
CLSID	CLSID_SWbemObject
IID	IID_ISWbemObject

Share via