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This example shows how travel guides are automatically notified by email whenever they are scheduled on a particular scheduled tour.
Technically, the email is sent when the record is stored (at record validation), since this is when the Rules Engine processes transitional multi-record constraints. If a rollback subsequently occurs, the mail action cannot be revoked. If you want to tie the mail action more closely to the commit event, you can present the user with a confirmation dialog at commit time, or you can flag the record and invoke the component later on the basis of the flag, or process mailing through a separate batch job in a separate transaction.
The example uses the Travel Agency case (Expanded Version).
Component
Component Name
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USMAIL
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Component Prog ID
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UsMail.Class1
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Method Name
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SEND_MAIL_EXE
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Physical Method Name
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send
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Parameters of RESOLVE_ADDRESS
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In - String
In - String
In - String
Return - Long Integer
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Query protocol association
Component Name
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USMAIL
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Protocol Name
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SEND_MAIL
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Exe Method Name
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SEND_MAIL_EXE
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Constraint
Constraint Name
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SEND_EMAIL
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Message
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Email address is not correct.
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Transition Table
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SCHEDTOUR
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Alias
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S
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Fire on Insert
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Always
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Fire on Delete
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Always
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Fire on Update
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Used Columns
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Set the SQL statement to:
INVOKE usmail.send_mail /* email address, subject, message-text */ WITH
SELECT
p.email,
'Tour guide',
'Dear ' || p.first_name ||
',
With this mail we would like to inform you that we have scheduled you as a guide on a tour to ' || s.destination || '.
Please contact the office as soon as possible for details.
Kind regards,
The Travel Agency.
'
FROM person p,
schedtour s
WHERE s.guide = p.person_id
AND p.email is not null
AND ( s.guide != old(s.guide)
or old(s.guide) is null
)
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Code of invoked subprogram
The component sends an email message to a Microsoft Exchange account using Microsoft's standard MAPI component. The recipient account depends on the input parameters of the INVOKE. The component then returns 0 (no violation) if the operation concludes normally, or -1 if an error occurs.
Visual Basic code of subprogram directly invoked by USoft:
Const USOFT_STATUS_VIOLATION = 1
Const USOFT_STATUS_NO_VIOLATION = 0
Const USOFT_STATUS_ERROR = -1
Public Function send(address As String, _
Optional subject As String, _
Optional text As String, _
Optional password As String, _
Optional profile_name As String, _
Optional silent As Boolean) _
As Long
' Initialize this function to return a violation
send = USOFT_STATUS_VIOLATION
Dim objSession As Object
Dim objMessage As Object
On Error GoTo on_error
' Apply defaults for optional arguments
If IsNull(silent) Then
silent = False
End If
' Create a objSession
Set objSession = newSession(profile_name:=profile_name, _
password:=password, _
no_mail:=False)
' Create a new message
Set objMessage = newMessage(objSession, address)
If Not IsNull(subject) Then
objMessage.subject = subject
End If
If Not IsNull(text) Then
objMessage.text = text
End If
objMessage.Recipients.Resolve
objMessage.send
If Not silent Then
MsgBox "Email successfully sent to " & address & "."
End If
cleanUp objSession, objMessage
send = USOFT_STATUS_NO_VIOLATION
Exit Function
on_error:
If Not ignoreError() Then
showError "send"
send = USOFT_STATUS_ERROR
End If
cleanUp objSession, objMessage
End Function
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See also
Using RDMI
Rules-Driven Method Invocation (RDMI)
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