Andreas Geppert

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Active object-oriented database management systems incorporate object-oriented database technology and active mechanisms such as event-condition-action rules (ECA-rules). SAMOS has been among the first representatives of this class of systems. During the development of SAMOS, numerous then open research questions have been addressed. In this paper, we(More)
In event-driven workflow execution, events and event-condition-action rules are the fundamental metaphors for defining and enforcing workflow logic. Processing entities enact workflows by reacting to and generating new events. The foundation on events also eases the integration of processing entities into coherent systems. In this paper, we present an event(More)
This paper describes the active, object-oriented database system SAMOS being developed as a research prototype. Its main approach is the integration of rules in the sense of active database systems into a general object-oriented data model. Our effort is also focussed on integrating the rule system with transaction processing in a meaningful way.
The exact semantics of workflows and involved processing entities is an open yet urgent problem. This paper considers the semantics and correctness of eventdriven workflow execution. The basis for the formalization in our approach is provided by an event history which records all events that have occurred during the execution of workflows. Workflows are(More)
Two concepts for the support of logical data independence in the context of the structurally object-oriented data model NO2 (New Object-Oriented data model) are presented: derived types and subschemas. In general, object types can be derived in two ways: derived types can restrict (the value set of) an existing base type, or new atrtibutes can be added to(More)
Interoperability and integration of data sources are becoming ever more important issues as both, the amount of data and the number of data producers are growing. Interoperability not only has to resolve the differences in data structures, it also has to deal with semantic heterogeneity. Semantics refer to the meaning of data in contrast to syntax, which(More)