Still speaking about COM+ vs SQL Server transactions, how problematic can be
using a class like the following (some kind of a decorator for a SQLTrans
object)? It's probably full of minor & MAJOR bugs but that's not the point,
the point is how usable can be something like this? I'm specially sensitive
to security drawbacks also (there are certainly some).
Public Class SharedTransaction
Private _Doomed As Boolean
Private _RootObjectHash As Integer
Private SQLTx As SqlClient.SqlTransaction
Private Con As SqlClient.SqlConnection
Public Sub New(ByVal ConnectionString As String, ByVal Root As
Object)
'Store some kind of Id for the root object of the transaction
_RootObjectHash = Root.GetHashCode 'possibly unsafe check,
testing
'Open proper connection & begin transaction
Con = New SqlClient.SqlConnection(ConnectionString)
Con.Open()
SQLTx = Con.BeginTransaction
'By default
_Doomed = False
End Sub
Public Sub Join(ByVal Com As SqlClient.SqlCommand)
'Makes the command execute inside our Transaction
Com.Transaction = SQLTx
Com.Connection = Con
End Sub
Public Function Commit(ByVal Caller As Object)
'Some kind of a COM+ SetComplete
If Caller.GetHashCode = _RootObjectHash Then
'Final
If _Doomed Then
'Someone has voted for rollback
SQLTx.Rollback()
Else
'Everything went fine
SQLTx.Commit()
End If
Con.Close()
Con.Dispose()
SQLTx.Dispose()
End If
End Function
Public Function Rollback(ByVal Caller As Object)
'Some kind of a COM+ SetAbort
If Caller.GetHashCode = _RootObjectHash Then
'Final
SQLTx.Rollback()
Con.Close()
Con.Dispose()
SQLTx.Dispose()
Else
_Doomed = True
End If
End Function
End Class
My thoughts:
Clients (web, win32,etc) make calls to tx business objects without passing
any kind of a SharedT instance (optional value with a default of nothing),
so it's still stateless enough to be used remotely with nlbs or web
services. Tx business objects will create a new SharedT if none is passed to
them, they can choose wether to pass a SharedT when locally calling other
tx business objects methods.
We span the transaction only when needed (I think it will be needed most of
the times). We don't use COM+/DTC serializable transactions but ADO.NET SQL
transactions (so we are able to define the appropriate isolation level).
I doubt that this can be a valid and stable solution (altough it's working
fairly well), but anyway, I was just testing possible scenarios.
RQ
You can read messages from the Advanced DOTNET archive, unsubscribe from Advanced
DOTNET, or
subscribe to other DevelopMentor lists at http://discuss.develop.com.
