Using constraints to manage long duration transactions in spatial information systems

Spatial information systems are employed to record the schematics of large networks for utilities and telecommunication organisations. Concurrent users access the spatial information systems to insert new designs, update designs and to record the current status of the network. Concurrency must be managed such that the data is not corrupted. This paper introduces a model for long duration transactions based on the use of integrity constraints. The model, called COLT (COnstraint-based Long Transaction), is domain-independent but is especially suitable for spatial information systems and domains where its intent naturally manifests constraints that relate data items. User-defined constraints and database integrity constraints are used both to specify the correctness criteria and to manage long duration ad-hoc transactions. The model is a generalisation of the traditional ACID transaction model. The approach enables the specification of the correctness criteria to be declarative and the user needs no knowledge of the semantics of other concurrently executing transactions. The COLT model is formally specified using the external actions of the I/O automata method and correctness is defined with respect to that method. Correctness is defined independent of implementation.