Journal validation

here is a sample:

	Public Class MainClass
		Public Function Main(ByVal si As SessionInfo, ByVal globals As BRGlobals, ByVal api As Object, ByVal args As JournalsEventHandlerArgs) As Object
			Try
				Dim returnValue As Object = args.DefaultReturnValue
				args.UseReturnValueFromBusinessRule = False
				args.Cancel = False
				
				If args.OperationName = BREventOperationType.Journals.PostJournal Then
					Me.HandlePostJournal(si, globals, api, args)
				End If		

				Return returnValue
			Catch ex As Exception
				Throw ErrorHandler.LogWrite(si, New XFException(si, ex))
			End Try
		End Function

#Region "Post Helpers"

		Private Sub HandlePostJournal(ByVal si As SessionInfo, ByVal globals As BRGlobals, ByVal api As Object, ByVal args As JournalsEventHandlerArgs)
			'------------------------------------------------------------------------------------------------------------
			'Reference Code: 	HandlePostJournal 
			'
			'Description:		
			'
			'------------------------------------------------------------------------------------------------------------
			Try

				If (args.IsBeforeEvent = True) Then
					Dim scenarioTypeId As Integer = BRApi.Workflow.General.GetScenarioTypeId(si, si.WorkflowClusterPk)
					Dim journalID As Guid = CType(args.Inputs(0), Guid)
					Dim journal As JournalEx = BRApi.Journals.Metadata.GetJournalOrTemplate(si, journalID)								

					If Not journal Is Nothing Then						
						Dim debitAmount As Decimal = 0
						Dim creditAmount As Decimal = 0
						For Each oneJournal As JournalLineItemEx In journal.LineItems
							
							debitAmount += oneJournal.LineItem.DebitAmount.Amount
							creditAmount += oneJournal.LineItem.CreditAmount.Amount

						Next

						If Math.Abs(debitAmount - creditAmount) > 100 Then
							
							Throw New Exception("Don't mess with Debit and Credit")
							
						End If	
							
					End If
				End If
				
			Catch ex As Exception
				Throw ErrorHandler.LogWrite(si, New XFException(si, ex))
			End Try
		End Sub

#End Region	
	End Class