Application crashes and transactions in .NET

Question

Suppose I have a application that handles money transfers.

try {
    transaction.Commit();
}  catch {
    transaction.Rollback();
}

Now what happens, if it turns out that the Commit has to be canceled, and for some reason the program crashes before the cancel or rollback is handled? How can I program my application so that it will be robust against program crashes.

EDIT: What if I don't have an SQL backend, and the transaction is something I myself have implemented?

Answer 1

Data persistence in Db would be achieved only after the Commit is successfull. So if your Commit fails in any position, the data would not be written to db.

Answer 2

Your design is fine (even if very minimalist with no real example in it...)

you can imagine that once you call var transaction = connection.BeginTransaction();

if you do not call commit the transaction will not get committed so the catch will roll it back.

if for any reason a crash prevents execution of the catch block auto rollback will be applied by the SQL engine.