This paper describes a software architectural design method for large-scale distributed information systems. The method, which is part of an integrated design and performance evaluation method, addresses the design of...
This paper describes a software architectural design method for large-scale distributed information systems. The method, which is part of an integrated design and performance evaluation method, addresses the design of client/server software architectures, where the servers need to cooperate with each other to service client requests. The goal of this software architecture is to provide a concurrent message based design that is highly configurable. The method is illustrated by applying it to the design of a complex software system, the Earth Observing System Data and Information System (EOSDIS) Core System.
Real time logic (RTL) was introduced as a formalism for reasoning about the relative and absolute timing properties of computational tasks of discrete real-time systems. Extended real time logic (ERTL) is a formalism ...
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Extended Real Time Logic (ERTL) is proposed for the modelling and analysis of hybrid systems, taking as a basis Real Time Logic (RTL). RTL is a first order logic with uninterpreted predicates which relate events of a ...
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The Center of Excellence for software and systemsengineering (CECASE) at the University of Kansas was established by the State of Kansas as a vehicle for developing and transferring advanced technology to Kansas busi...
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The Center of Excellence for software and systemsengineering (CECASE) at the University of Kansas was established by the State of Kansas as a vehicle for developing and transferring advanced technology to Kansas businesses. In this paper we describe three CECASE projects that used three different methods of successfully transferring advanced Artificial Intelligence (AI) technology to Kansas companies. We describe the problems encountered, approaches tried, and successful solutions used. These projects and associated Al technology transfer methods can be used as models by other research and development organizations who wish to enhance the probability of success of their technology transfer.
View materialization is known to be a valuable technique for performance optimization in relational databases, and much work has been done addressing the problem of consistently maintaining relational views under upda...
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View materialization is known to be a valuable technique for performance optimization in relational databases, and much work has been done addressing the problem of consistently maintaining relational views under update operations. However, little progress has been made thus far regarding the topic of view materialization in object-oriented databases (OODBs). In this paper, we demonstrate that there are several significant differences between the relational and object-oriented paradigms that can be exploited when addressing the object-oriented view materialization problem. We use the subsumption relationships between classes to identify branches of classes to which we do not need to propagate updates. Similarly, we use encapsulated interfaces combined with the fact that any unique database property is inherited from a single location to provide a "registration/notification" service for optimizing incremental view updates. We also report results from the experimental studies we have run on the MultiView system measuring the impact of these optimization strategies.
Materialized complex object-oriented views are a promising technique for the integration of heterogeneous databases and the development of powerful data warehousing systems. Path query views are virtual classes formed...
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Materialized complex object-oriented views are a promising technique for the integration of heterogeneous databases and the development of powerful data warehousing systems. Path query views are virtual classes formed from selection queries that specify a predicate upon the value of an aggregation hierarchy path. The primary difference between previous work regarding OODB indexing and the efficient implementation of materialized path query views addressed in this paper lies in the nature of their usage. For OODB indexing, query usage is the primary purpose of index structures. Because the materialized view data itself can be used to answer queries, the primary use of index structures with regard to materialized path query views is for the incremental maintenance of views in the face of updates. We have developed an augmented inherited multi-index (AIM) strategy that is specifically tailored for the maintenance of materialized path query views. We find that we can improve update performance by augmenting traditional inherited multi-indices with structured representations of the path queries that use them. This enables us to use class hierarchy relationships to prune the number of aggregation paths that must be re-instantiated during update propagation and also to support complex path queries that include cycles.
We have developed the transparent schema evolution (TSE) system that, simulating schema evolution using object-oriented views, allows for the interoperability of applications with diverse and even changing requirement...
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We have developed the transparent schema evolution (TSE) system that, simulating schema evolution using object-oriented views, allows for the interoperability of applications with diverse and even changing requirements. TSE relieves users of the risk of making existing application programs obsolete when run against the modified schema, because the old view schema is maintained while a new view schema is generated to capture the changes desired by the user. However TSE may be generating a large number of schema versions (object-oriented view schemata) over time, resulting in an excessive build-up of classes and underlying object instances-some of which may potentially no longer be in use. We propose to solve this problem by developing techniques for effective and consistent schema removal. First, we characterize four potential problems of schema consistency that could be caused by removal of a single virtual class; and then outline our solution approach for each of these problems. Second, we demonstrate that view schema removal is sensitive to the order in which individual classes are processed. Our solution to this problem is the development of a dependency graph model for capturing the class relationships, used as a foundation for selecting among removal sequences. Designed to optimize the performance of the TSE system by effective schema version removal, the proposed techniques will enable more effective interoperability among evolving software applications.
Summary form only given. Hybrid systems are systems which combine both continuous variable and discrete event dynamics. Their complexity has risen to the extent that traditional approaches which dealt separately with ...
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Summary form only given. Hybrid systems are systems which combine both continuous variable and discrete event dynamics. Their complexity has risen to the extent that traditional approaches which dealt separately with the continuous and discrete aspects of such systems have become obsolete. Instead of proposing a novel formal notation for the specification of controllers for hybrid systems we have developed extended real time Logic (ERTL) as a formal notation for the modelling and analysis of relative and absolute timing properties of hybrid systems. ERTL embeds the discrete system model of the real time logic (RTL) of Jahanian and Mok (1986, 1988) into continuous time, and adds the ability to reason about piecewise continuous functions using predicates over real valued variables. While RTL is able to formally describe the behaviour of computational entities in the time domain, ERTL also permits the formal description of the behaviour of physical entities in both value and time domains.
Real time logic (RTL) was introduced as a formalism for reasoning about the relative and absolute timing properties of computational tasks of discrete real-time systems. Extended real time logic (ERTL) is a formalism ...
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Real time logic (RTL) was introduced as a formalism for reasoning about the relative and absolute timing properties of computational tasks of discrete real-time systems. Extended real time logic (ERTL) is a formalism for the modelling and analysis of relative and absolute timing properties of hybrid systems (systems that combine continuous variables and discrete event dynamics). The extensions provided by ERTL enable the modelling of system behaviour ranging from activities of the physical entities that form part of the environment of a computing system, to the temporal ordering of the computational tasks of the computing system itself thus providing a formal notation that can be used in all stages of software development.
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