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International Conference on Data engineering

作者： H.A. Kuno E.A. Rundensteiner Department of Elect. Engineering and Computer Science Software Systems Research Laboratory University of Michigan Ann Arbor MI USA

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.

关键词： Object oriented modeling Relational databases Object oriented databases computer science software systems Laboratories Optimization Programming profession NASA Prototypes

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Augmented inherited multi-index structure for maintenance of materialized path query views

Augmented inherited multi-index structure for maintenance of...

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International Workshop on Research Issues in Data engineering

作者： H.A. Kuno E.A. Rundensteiner Department of Elect. Engineering and Computer Science Software Systems Research Laboratory University of Michigan Ann Arbor MI USA

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.

关键词： Object oriented databases Warehousing Indexing Distributed databases Workflow management software computer science software systems Laboratories Information technology Database systems

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Consistent view removal in transparent schema evolution systems

Consistent view removal in transparent schema evolution syst...

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International Workshop on Research Issues in Data engineering

作者： V. Crestana-Taube E.A. Rundensteiner Department of Elect. Engineering and Computer Science Software Systems Research Laboratory University of Michigan Ann Arbor MI USA

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.

关键词： Application software Object oriented modeling computer science software systems Laboratories Computational modeling Marine vehicles Design optimization software performance Veins

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ASPECT-an Architecture SPECification Technique a report on work in progress

ASPECT-an Architecture SPECification Technique a report on w...

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International Conference and Workshop on engineering of computer-Based systems

作者： V. Kirova W. Rossak Department of Computer and Information Science Department of Computer and Information Science New Jersey Institute of Technology Newark NJ USA Department of Computer and Information Science Department of Computer and Information Science Software and Systems Engineering Laboratory New Jersey Institute of Technology Newark NJ USA

We discuss ASPECT, a first step towards a generic specification technique for software architectures. We present and discuss an abstract grammar for ASPECT that lists and relates to each other all the architectural elements that form ASPECT's vocabulary. After elaborating on the characteristics of these architectural elements, we illustrate their application in a small example.

关键词： computer architecture software systems systems engineering and theory Laboratories software architecture Information science Open systems Costs Decision support systems Standardization

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Virtual memory versus file interfaces for large, memory-intensive scientific applications 96

Virtual memory versus file interfaces for large, memory-inte...

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Proceedings of the 1996 ACM/IEEE conference on Supercomputing

作者： Yoonho Park Ridgway Scott Stuart Sechrest High Performance Computing Center University of Houston Houston TX Software Systems Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI

ISBN: (纸本)9780897918541

Scientific applications often require some strategy for temporary data storage to do the largest possible simulations. The use of virtual memory for temporary data storage has received criticism because of performance problems. However, modern virtual memory found in recent operating systems such as Cenju-3/DE give application writers control over virtual memory policies. We demonstrate that custom virtual memory policies can dramatically reduce virtual memory overhead and allow applications to run out-of-core efficiently. We also demonstrate that the main advantage of virtual memory, namely programming simplicity, is not lost.

关键词： custom policies

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Incorporation of relational modeling method into object-oriented analysis

Incorporation of relational modeling method into object-orie...

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IEEE International Conference on Communications (ICC)

作者： Chung-Horng Lung J.E. Urban G.T. Mackulak Software Engineering Analysis Laboratory Nortel Technologies Inc. Ottawa ONT Canada Department of Computer Science Arizona State University Tempe AZ USA Systems Simulation Laboratory Industrial & Management Systems Engineering Arizona State University Tempe AZ USA

It is a generally accepted concept that multiple views are needed in object-oriented analysis or domain analysis techniques. Three commonly adopted models for requirements analysis include object model, functional model and dynamic model. This paper introduces and incorporates the concept of relational modeling into the analysis techniques. Relational modeling mainly deals with two tasks: classification of semantic relations and identification of higher-order system causal relations. Classification of semantic relations supports comparison and evaluation of various relations, which in turn can be used to select suitable methods to process the relations. A higher-order relation depicts the relations between different relations as opposed to the relations between objects often discussed in object modeling. A network of higher-order relations reveals the cause-effect dependency relationships and can facilitate understanding and reasoning of application systems. Furthermore, incorporation of relational modeling techniques can support software reuse in an application domain or across domains.

关键词： Object oriented modeling Application software Lungs computer science Computational modeling Analytical models computer simulation Laboratories Seals software engineering

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Virtual Memory versus File Interface for Large, Memory-Intensive Scientific Applications

Virtual Memory versus File Interface for Large, Memory-Inten...

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Supercomputing Conference

作者： Yoonho Park R. Scott S. Sechrest High performance computing center University of Houston Houston TX USA Software Systems Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

关键词： Memory Operating systems Control systems

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PROGRAM VIEW GENERATION AND CHANGE ANALYSIS USING ATTRIBUTED DEPENDENCY GRAPHS

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JOURNAL OF software MAINTENANCE-RESEARCH AND PRACTICE 1995年第4期7卷 239-261页

作者： ALZOUBI, R PRAKASH, A Software Systems Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2122 U.S.A. He is currently an Assistant Professor at Yarmouk University Irbed H.K. of Jordan. Earlier he has worked for the Ford Motor Company in Dearborn Michigan. His research interests are in the area of software engineering. Since 1989 he has been with the Department of Electrical Engineering and Computer Science at the University of Michigan Ann Arbor where he is currently an Associate Professor. His research interests include software engineering and computer-supported cooperative work. He is a member of the ACM and the IEEE Computer Society.

software maintenance is usually the most expensive phase of the software life-cycle, Program understanding and impact-of-change analysis are two of the major activities during this phase, In this paper, we describe attributed program dependency graphs (APDGs), a model to store information derived from the program source code and ease construction of tools for software maintenance, We show how the model can be used for interactive view generation and doing two kinds of impact-of-change analysis-incremental and comparison-oriented. Incremental change analysis uses APDGs and a Rule Base to provide a way for the user to analysis the effect of proposed well-defined changes, Comparison-oriented change analysis allows a user to generate structural semantic differences between two versions of a subsystem after an arbitrary sequence of changes, We also introduce SCAN, a prototype collection of loosely integrated tools based on the APDG model and describe our experiences with the system.

关键词： PROGRAM REPRESENTATION DEPENDENCY GRAPHS PROGRAM UNDERSTANDING REVERSE-engineering REengineering IMPACT ANALYSIS CHANGE ANALYSIS

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Implementation of a discretionary access control model for script-based systems

Implementation of a discretionary access control model for s...

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computer Security Foundations Workshop

作者： T. Jaeger A. Prakash Software Systems Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

Powerful applications can be implemented using command scripts. A command script is a program written by one user, called a writer, and made available to another user, called the reader, who executes the script. For instance, command scripts could be used by Mosaic, the popular World-wide Web browsing tool, to provide fancy interfaces to services, such as banking, shopping, etc. However, the use of command scripts presents a serious security problem. A command script is run with the reader's access rights, so a writer can use a command script to gain unauthorized access to the reader's data and applications. Existing solutions to the problem either severely restrict I/O capability of scripts, limiting the range of applications that can be supported, or permit all I/O to scripts, potentially compromising the security of the reader's data. We define a discretionary access control model that permits users to flexibly limit the access rights of the processes that execute a command script. We use this model in a prototype system that safely executes command scripts available from Mosaic.

关键词： Access control Permission Postal services Power system modeling File systems Data security software systems Laboratories Electronic mail Application software

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Materialized object-oriented views in MultiView

Materialized object-oriented views in MultiView

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International Workshop on Research Issues in Data engineering

作者： H.A. Kuno E.A. Rundensteiner Department of Electrical Engineering and Computer Science Software Systems Research Laboratory University of Michigan Ann Arbor MI USA

Object-oriented view mechanisms have received much attention in the literature in recent years, since they provide powerful mechanisms for addressing tasks such as customized tool interfacing to object-oriented databases (OODBs) and interoperability of heterogeneous databases. However, little progress has been made thus far on addressing the topic of view materialization in object-oriented databases. In the context of the MultiView project, we have developed an object model and an accompanying set of algorithms for the support of updatable materialized views in OODBs. We take advantage of unique features of the MultiView model, including its support for object-preserving queries, the integration of base and virtual classes into a unified and consistent global class hierarchy, and an object-slicing approach. In this paper, we present the MultiView model of materialized views, supporting updates on both base and virtual classes. We also describe a set of efficient algorithms for incremental view maintenance.< >

关键词： Object oriented modeling Object oriented databases computer science software systems Spatial databases Context modeling NASA Prototypes

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