19.2. Transaction specification and programming

It is useful to extend the concept of atomic operation to include composite operations. We assume that it is the composite operation that has meaning to whatever application invoked it; the suboperations are related and all or none of them must be carried out. Recall the operation hierarchy of Section 17.1 and Figures 17.4 and 17.7. It is the operation at the outermost level shown in the figures that is meaningful to the application; the application may not even be aware of the suboperations carried out by the system. In a banking system, for example, to credit an account with an amount, to debit an account with an amount, or to transfer an amount from one account to another are all operations that ...

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