A data modeling approach for office information systems
ACM Transactions on Information Systems (TOIS)
Exception handling: issues and a proposed notation
Communications of the ACM
Fundamentals of Programming Languages
Fundamentals of Programming Languages
A Transaction Mechanism for Engineering Design Databases
VLDB '84 Proceedings of the 10th International Conference on Very Large Data Bases
Consistency and Transactions in CAD Database
VLDB '82 Proceedings of the 8th International Conference on Very Large Data Bases
SOS: a conceptual model for office information systems
ACM SIGMIS Database - Database techniques and models for the office environment: selected papers from the Database Week Conference
Situation monitoring for active databases
VLDB '89 Proceedings of the 15th international conference on Very large data bases
Agent-based intelligent information dissemination in dynamically changing environments
Intelligent agents and their applications
Managing Change in a Computer-Aided Design Database
VLDB '87 Proceedings of the 13th International Conference on Very Large Data Bases
Events and streams: harnessing and unleashing their synergy!
Proceedings of the second international conference on Distributed event-based systems
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Data objects in engineering applications, especially computer aided design, show highly complex structures and a lot of intricate dependencies. Hence a large amount of variably composed consistency constraints have to be dealt with. Furthermore, long transactions which are typical for CAD result in the need to tolerate inconsistencies over unpredictably long periods of time. The demands on mechanisms to enforce consistency in design database systems thus differ from those in business and administrative applications. Comprehensive consistency of the design data can only be attained by degrees. The time and extent of checking have to be determined dynamically and under control by the user. In the case of consistency violations, flexible kinds of reaction are necessary. In this paper we propose an event/trigger mechanism to enforce consistency in design databases that complements the transaction-oriented mechanisms suitable for traditional applications. The underlying ideas are derived from exception handling in programming languages. We present in detail the requirements to meet and how our concept copes with them. We also present an implementation that provides reasonable performance.