INFO: Data Types Supported in COM+ Events Filters (256989)

SUMMARY

COM+ Events have event classes and subscribers. Subscribers can be configured to be fired or not depending on the actual function argument values. These values are specified in the Filter property for the subscriber.

Not all parameters may be used in a filter; some data types are not supported.

MORE INFORMATION

The following is a list of supported data types for COM+ Event subscriber filters:

signed char
signed short
signed int 
signed long
signed long long
unsigned char
unsigned short
unsigned int
unsigned long
unsigned long long
boolean
UNICODE string //(BSTR or WCHAR*)
GUID

The following is a list of the data types supported in Visual Basic:

Integer
Long
Byte
String
Boolean

All other data types are not supported. For example, the following is not supported:

Public MyEvent(ByVal Param1 As Long, ByVal Param2 As Variant)

End Sub

In a COM+ snap-in, you can use the following criteria,

Param1=2

because Param1 is declared as a long, which is supported.

You cannot use the following,

Param2="Value"

because Param2 is declared as a Variant, which is not supported.

Note the following issues:

These restrictions apply to subscriber (not publisher) filtering.
The Variant data type specifically is not supported.
Scriptlet subscribers cannot use subscriber filtering (they use Variant data types).

REFERENCES

For more information, please see the following Web sites:

MSDN: COM+ Events:
http://msdn.microsoft.com/library/psdk/cossdk/pgservices_events_2y9f.htm
MSJ: The COM+ Event Service Eases the Pain of Publishing and Subscribing to Data, September 1999:
http://msdn.microsoft.com/library/periodic/period99/com+event.htm
MSDN: Parameter Filtering:
http://msdn.microsoft.com/library/psdk/cossdk/pgservices_events_8iuf.htm