I develop a three tiers application in VB6, client-server architecture.
The User interface tier is a VB6 EXE project. The Business tier is a VB6 Active X COM project (DLL) that has some classes.
The data are introduced by a VB form of User interface tier, but is validated in Business tier?s property functions.
When a data isn?t OK (wrong data), I have to write a message on the screen and retry the data input flow in the User interface tier input procedure.
My problem is:
How can Business object tier procedure to tell User interface tier procedure that there are an error (and it have to retry the data input).
I have try to use err.Raise in Business tier procedure, but User interface tier procedure isn?t interrupted by an error:
On Error goto err:
Object.member=value ?call the property function of member of object.
?The property contains err.Raise
Msgbox ?is ok?
Msgbox ?I was interrupted by an error?
I see ?is ok?.
Is this unpleasant situation related to the following sentences from MSDN Library Visual Studio 6.0 help: ?System errors during calls to Windows DLL do not raise exceptions and cannot by trapped with Visual Basic Error trapping? ?
How can I trap validation errors from Business object tier procedure?