We present an exception handling facility suitable for languages used to implement database-intensive Information Systems. Such a mechanism facilitates the development and maintenance of more flexible software systems by supporting the abstraction of details concerning special or abnormal occurrences. We consider the type constraints imposed by the schema as well as various semantic integrity assertions to be normalcy conditions, and the key contribution of this work is to allow exceptions to these constraints to persist. To achieve this, we propose solutions to a range of problems, including sharing and computing with exceptional information, exception handling by users, the logic of constraints with exceptions, and implementation issues. We also illustrate the use of exception handling in dealing with null values, estimates, and measurements. Keywords and phrases: semantic integrity, violations of type constraints, exception handling, accommodating exceptions, conceptual models CR ...

Practical workflow systems need to be able to tolerate deviations from the initial process model because of un-anticipated situations. They should also be able to accommodate deviations in the format of the forms and data being manipulated. We offer a framework for treating both kinds of deviations uniformly, by applying ideas from programming languages (with workflow agents as potential on-line exception handlers) to workows that have been reified as objects in classes with special attributes. As a result, only a small number of new constructs, which can be applied orthogonally, need to be introduced. Special run-time checks are used to deal with the consequences of permitting deviations from the norm to persist as violations of constraints.

A computer system which stores, retrieves and manipulates information about some portion of the real world can be viewed as a model of that domain of discourse. There has been considerable research recently on languages which allow one to capture more of the semantics of the real world in these computerized Information Systems-- research which has variously been labelled as Semantic Data Modeling, Semantic Modeling or Conceptual Modeling. This review paper presents a list of the features which appear to distinguish these languages from those traditionally used to describe and develop database-intensive applications, and considers the motivation for these features as well as the potential advantages to be gained through their use. The paper, which is intended for those familiar with current data processing practices, also compares in greater detail four programming languages which incorporate semantic modeling facilities, and discusses some of the methodologies and tools for Information System development based on these languages.

Exceptions form an essential feature of administrative systems (Auramäki and Leppänen, 1989) and they are a major component of administrative work (Strong and Miller, 1989). When concepts of administrative work are defined,

Exceptions are events that cannot be handled by an information system by following normal processing rules. Exceptions arise for two main reasons: flaws in system design and post implementation changes in the system domain. Only few exceptions should arise in an information system serving its user community well. In practice, this is rarely the case and exceptions are sometimes rather common even with routine processes. In this paper, an exception-based approach to evaluate information systems is presented together with practical examples of its use. The benefits of the analysis to information system management are elaborated on.

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This paper describes a novel knowledge-based approach for helping workflow process designers and participants better manage the exceptions (deviations from an ideal collaborative work process caused by errors, failures, resource or requirements changes etc.) that can occur during the enactment of a workflow. This approach is based on exploiting a generic and reusable body of knowledge concerning what kinds of exceptions can occur in collaborative work processes, and how these exceptions can handled (detected, diagnosed and resolved). This work builds upon previous efforts from the MIT Process Handbook project and from research on conflict management in collaborative design.