Springer Online Journal Archives 1860-2000
Summary We defineinterface, module and the meaning ofM offers I, whereM denotes a module andI an interface. For a moduleM and disjoint interfacesU andL, the meaning ofM using L offers U is also defined. For a linear hierarchy of modules and interfaces,M 1, I1, M2, I2, ...,M n, In, we present the following composition theorem: IfM 1 offersI 1 and, fori=2, ...,n, M i usingI i−1 offersI i, then the hierarchy of modules offersI n. Our theory is applied to solve a problem posed by Leslie Lamport at the 1987 Lake Arrowhead Workshop. We first present a formal specification of a serializable database interface. We then provide specifications of two modules, one based upon two-phase locking and the other multi-version timestamps; the two-phase locking module uses an interface offered by a physical database. We prove that each module offers the serializable interface.
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