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A software architectural design method for large-scale distributed information systems

Distributed systems engineering 1996年第3期3.0卷 162-172页

作者： Gomaa, Hassan Menascé, Daniel Kerschberg, Larry Department of Information and Software Systems Engineering George Mason University Fairfax VA 22030-4444 United States Department of Computer Science George Mason University Fairfax VA 22030-4444 United States

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.

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Optimizing the NASA technical report server

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INTERNET RESEARCH-ELECTRONIC NETWORKING APPLICATIONS AND POLICY 1996年第1期6卷 64-&页

作者： Nelson, ML Maa, MH Michael L. Nelson is the “webmaster” for NASA Langley Research Center Computer Systems Branch Mail Stop 157A 15 Langley Boulevard Hampton VA 23681‐0001 USA. Tel: 804 8648511 Fax: 804 8648342 E‐mail: <m.l.nelson@larc.nasa.gov> . He has also worked with others to implement report servers software servers technology transfer databases and other World Wide Web services and is also the technical lead for NASA Langley Research Center’s workstation clustering activities. Ming‐Hokng Maa is a NASA Langley Research Center Cooperative Education Student e‐mail: <m.h.maa@larc.nasa.gov> pursuing his BS in computer engineering/computer science at the Massachusetts Institute of Technology. He has previously held research positions at nView Corp. and the Inter‐National Research Institute Inc Ming‐Hokng Maa is a NASA Langley Research Center Cooperative Education Student e‐mail: <m.h.maa@larc.nasa.gov> pursuing his BS in computer engineering/computer science at the Massachusetts Institute of Technology. He has previously held research positions at nView Corp. and the Inter‐National Research Institute Inc

Explains how the NASA Technical Report Server, a World Wide Web report distribution NASA technical publications service, has been modified for performance enhancement, greater protocol support and human interface optimization. Results include: parallel database queries, significantly decreasing user access times by an average factor of 2.3;access from clients behind firewalls and/or proxies which truncate excessively long Uniform Resource Locators;access to non-Wide Area Information Server (WAIS) databases and compatibility with the Z39-50.3 protocol;and a streamlined user interface.

关键词： distribution information retrieval information services Internet

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Coating mass control on No. 2 galvanizing line at LTV Steel's Indiana Harbor works

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Iron and Steel Engineer 1996年第1期73卷 22-22页

作者： Adams, J. Miles, L. Bohney Parker, D.J. Conway, G. Wallace, G. Computer Systems Technology Center Independence OH United States Indiana Harbor Works LTV Steel Co. Inc. East Chicago IN United States Software Engineering Special Projects Indust. Automat. Services Pty. Ltd. Toronto NSW Australia

A high-performance coating mass control system was designed using an analytical first principles model and advanced control methods. This computer control system was installed and successfully commissioned in March 1994 on the No. 2 continuous galvanizing line at LTV Steel's Indiana Harbor works. Commissioning was fast and smooth due to the use of a process simulator, task partitioning for parallel subsystem development, good project management methods and close cooperation of the three participating companies. Significant improvements were achieved for coating mass uniformity, reduced skew coating footage, reduced order change footage, reduced rejects for coating reasons and reduced zinc usage. This control system and the line upgrade projects that preceded it have made the No. 2 continuous galvanizing line a state of the art hot dip facility for producing the highest quality galvannealed and galvanized products that meet the needs of the most demanding customers and applications. Current work is focused on enhancing product performance, achieving additional zinc savings, and development of new products made possible by improved coating uniformity and tighter coating control. Additional projects in progress for this line include upgrading the air supply system, the knife positioning and measuring systems, and running trials for new products. Upgrading programs for LTV's other coating lines are following the example set by the No. 2 CGL.

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A method for understanding intentions of indirect speech acts in natural language interfaces

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systems AND computerS IN JAPAN 1996年第1期27卷 77-91页

作者： Mima, H Aoe, J Fuketa, M Hayashi, Y Member Faculty of Engineering The University of Tokushima Tokushima Japan 770 Jun-ichi Aoe received his B.E. and M.E. degrees in Electronic Engineering from the University of Tokushima Tokushima Japan in 1974 and 1976 respectively and his Ph.D. degree in Communication Engineering from the University of Osaka Japan in 1980. Since 1976 he has been with the University of Tokushima. He is currently a Professor in the Department of Information Science and Intelligent Systems at the University of Tokushima. He is the author of about 50 scientific papers. His research interests include computer algorithms in software engineering and natural language processing. Dr. Aoe is editing Computer Algorithms Series of the IEEE Computer Society Press and author of two books: Computer Algorithms-Key Search Strategies in 1991 and String Pattern Matching Strategies in 1994. He received a Best Author Award from the Information Processing Society of Japan in 1993. He is a member of the Association for Computing Machinery the American Association for Artificial Intelligence the Association for Computational Linguistics and the Information Processing Society of Japan the Society for Software Science and Technology the Japanese Society for Artificial Intelligence and the Association for Natural Language Processing of Japan. Nonmember

In an attempt to propose a robust method for understanding natural language (NL) interface commands, a scheme is proposed that infers intentions from an indirect speech-act that does not express users' real intentions explicitly. This method classifies the real intentions of the indirect speech-act into: 1) refusal;2) reversal;3) restriction;4) benefit;and 5) disability. Further, concepts are abstracted for operations, e.g., displaying, moving, and deleting information systems;and constructing the operation knowledge base. This knowledge based comprises operational concepts and the relationships between them. These relationships are assigned the foregoing classifications for intentions. In addition, we construct the knowledge base of objects for the target of operations, e.g., files, figures, strings. This knowledge base contains the relationships: a) antonym;b) exclusive;c) part-of, between the objects;and uses these relations to infer the transitions between the objects. An algorithm is the proposed to infer concepts for operations and concepts for target objects of operations that may represent the user's actual intentions. This proposal scheme was tested with requests on UNIX and a commercially available Japanese Word Processor. The system successfully inferred the intentions for approximately 80 percent of the user's indirect speech-act.

关键词： natural language interface indirect speech act inference of intention

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TheMultiViewOODB view system: Design and implementation

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Theory and Practice of Object systems 1996年第3期2卷

作者： Harumi A. Kuno Elke A. Rundensteiner Dept. of Elect. Engineering and Computer Science Software Systems Research Laboratory The University of Michigan 1301 Beal Avenue Ann Arbor MI 48109-2122 rundenst@eecs.umich.edu

Views are an established technique for restructuring and repartitioning the format of data, classes, and schemata so that applications can customize shared data objects without affecting other applications' perceptions of the data. The MultiView system is one of the first OODB systems to support dynamic and updatable materialized object-oriented database views. MultiView is fully functional and is being used for a number of projects. In this article, we describe our system's architecture, the services it provides, and the decisions we made during our implementation. Although the GemStone system we chose for our implementation base offers many features that greatly aided our implementation, it does not support several key object-model properties that are critical for the realization of our design principles. These fundamental properties include multiple classification, dynamic object-restructuring, and the ability to make dynamic changes to the schema. We hence adopted a flexible and powerful technique known as object-slicing to construct the MultiView object model. This object-slicing architecture successfully addresses our requirements. The MultiView system is distinguished by a number of unique features, including the incorporation of virtual classes into the global schema as first-class database citizens, support for capacity-augmenting views (virtual classes that add new extrinsic properties or behavior), view materialization strategies that take advantage of object-oriented modeling features, and a graphical interface that is tailored to provide easy access to the MultiView system. The resulting system preserves all of the capabilities of the underlying GemStone OODB while providing support for dynamic and updatable materialized object-oriented views. © 1996 John Wiley & Sons, Inc.

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CRITICAL BANDWIDTH ALLOCATION FOR THE DELIVERY OF COMPRESSED VIDEO

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computer COMMUNICATIONS 1995年第10期18卷 709-717页

作者： FENG, WC SECHREST, S Software Systems Research Lab Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

The transportation of compressed video data without loss of picture quality requires the network to support large fluctuations in bandwidth requirements. These fluctuations can be smoothed, but straightforward approaches to smoothing can still suffer from excessive buffering requirements, poor buffer utilization and an excessive number of bandwidth changes. This paper introduces critical bandwidth allocation, which reduces the number of bandwidth changes to a very small number, and achieves the maximum effectiveness from client-side buffers. A comparison between critical bandwidth allocation algorithms and other smoothing algorithms is presented, the sensitivity of the algorithm to jitter is examined, and, implications for the design of network services are discussed.

关键词： VIDEO-ON-DEMAND BANDWIDTH ALLOCATION MPEG VIDEO COMPRESSION SMOOTHING

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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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Specification and design of distributed hard real-time systems

Specification and design of distributed hard real-time syste...

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1995 Euromicro Workshop on Parallel and Distributed Processing

作者： Roberto, Paulo Tepedino, Pierri Kimer, Tereza Gonçalves State University of São Paulo Unesp Bauru-SP Brazil Department of Computer Science UFSCar São Carlos-SP Brazil Ceoterfor Software and Systems Engineering University of Colorado Colorado Springs United States

ISBN: (纸本)0818670312

This paper presents an integrated approach for specification and design of software for distributed hard real-time systems. The approach adopts a graph-based model, combined with a pre-run-time scheduling. This gives important features to the approach, making {possible the solution of crucial questions along the development of these systems. © 1995 IEEE.

关键词： Real time systems

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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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