Pattern Reification as the Basis for Description-Driven Systems

One of the main factors driving object-oriented software development for information systems is the requirement for systems to be tolerant to change. To address this issue in designing systems, this paper proposes a pattern-based, object-oriented, description-driven system (DDS) architecture as an extension to the standard UML four-layer meta-model. A DDS architecture is proposed in which aspects of both static and dynamic systems behavior can be captured via descriptive models and meta-models. The proposed architecture embodies four main elements - firstly, the adoption of a multi-layered meta-modeling architecture and reflective meta-level architecture, secondly the identification of four data modeling relationships that can be made explicit such that they can be modified dynamically, thirdly the identification of five design patterns which have emerged from practice and have proved essential in providing reusable building blocks for data management, and fourthly the encoding of the structural properties of the five design patterns by means of one fundamental pattern, the Graph pattern. A practical example of this philosophy, the CRISTAL project, is used to demonstrate the use of description-driven data objects to handle system evolution.Comment: 20 pages, 10 figure

A First Approach on Modelling Staff Proactiveness in Retail Simulation Models

There has been a noticeable shift in the relative composition of the industry in the developed countries in recent years; manufacturing is decreasing while the service sector is becoming more important. However, currently most simulation models for investigating service systems are still built in the same way as manufacturing simulation models, using a process-oriented world view, i.e. they model the flow of passive entities through a system. These kinds of models allow studying aspects of operational management but are not well suited for studying the dynamics that appear in service systems due to human behaviour. For these kinds of studies we require tools that allow modelling the system and entities using an object-oriented world view, where intelligent objects serve as abstract \'actors\' that are goal directed and can behave proactively. In our work we combine process-oriented discrete event simulation modelling and object-oriented agent based simulation modelling to investigate the impact of people management practices on retail productivity. In this paper, we reveal in a series of experiments what impact considering proactivity can have on the output accuracy of simulation models of human centric systems. The model and data we use for this investigation are based on a case study in a UK department store. We show that considering proactivity positively influences the validity of these kinds of models and therefore allows analysts to make better recommendations regarding strategies to apply people management practices.Retail Performance, Management Practices, Proactive Behaviour, Service Experience, Agent-Based Modelling, Simulation

Transaction management in object-oriented data base systems

Object-oriented data bases are fast gaining in popularity, especially with the advent of advanced applications like computer aided design (CAD) and multimedia data bases (MMDB). The modeling techniques required by these applications cannot be met by conventional data base systems. The semantic richness of the object-oriented model facilitates the modeling of advanced data base applications. These applications are characterized by long-duration cooperating transactions. Unlike the conventional data bases, serializability can no linger be the correctness criterion for concurrent transaction execution. A new transaction model for object-oriented data bases is needed. This dissertation describes our research in the area of transaction management for object-oriented data bases. A new transaction model for object-oriented data bases is defined. This model takes into consideration the unique requirements of the advanced applications. Data base consistency is now defined in terms of correctability. Object-oriented Correct Schedules (OOCS) and Object-oriented Correctable Schedules (OOCLS) are defined. This dissertation also describes a new concurrency control protocol that satisfies the correctness criterion for concurrent execution of transactions in an object-oriented data base environment, i.e. it allows only Object-oriented Correctable Schedules. Users of a data base interact with it through means of queries. Queries are then translated into transactions. The data base functionality necessary to support queries is also discussed in this research work

A Collection Model for Data Management in Object-Oriented Systems

This thesis addresses the question of how to provide data management services in object-oriented systems with reliable persistent object stores. It proposes an object data model, called the collection model, which serves as a foundation for the construction of such services. The collection model is general in that it is independent of any particular implementation platform. In part, this independence is achieved through the separation of the data model from the underlying type model. There are two components of the collection model - a structural model, BROOM, and an operational model based on an algebra of collections. The structural model is semantically rich and exhibits properties of both the entity-relationship and semantic data models. Hoary collections are used to represent entity categories and binary collections to represent relationships between entities. Classification structures are based on the notion of a. collection family which represents various forms of conceptual dependencies among the collections of a. family. The requirements for supporting the various forms of evolution in object-oriented database systems are presented. An extension to the collection model is proposed to support object evolution whereby objects can migrate within classification structures. Two existing realisations of the collection model are described. One is a. prototype, single-user system implemented in Prolog. The other forms the basis of the Object Data. Management Services of the Comandos platform for distributed, object-oriented applications. A general approach to object data model design, specification and realisation is advocated. In particular, a metacircular description of the collection model is used as an intermediate form of data model specification. This metacircular description is then transformed into a formal specification in the Z language

Advanced software development workstation. Comparison of two object-oriented development methodologies

This report is an attempt to clarify some of the concerns raised about the OMT method, specifically that OMT is weaker than the Booch method in a few key areas. This interim report specifically addresses the following issues: (1) is OMT object-oriented or only data-driven?; (2) can OMT be used as a front-end to implementation in C++?; (3) the inheritance concept in OMT is in contradiction with the 'pure and real' inheritance concept found in object-oriented (OO) design; (4) low support for software life-cycle issues, for project and risk management; (5) uselessness of functional modeling for the ROSE project; and (6) problems with event-driven and simulation systems. The conclusion of this report is that both Booch's method and Rumbaugh's method are good OO methods, each with strengths and weaknesses in different areas of the development process

Storage management and indexing in object-oriented database management systems

Ankara : The Department of Computer Engineering and Information Sciences and the Institute of Engineering and Sciences of Bilkent Univ., 1990.Thesis (Master's) -- Bilkent University, 1990.Includes bibliographical references leaves 76-77Storage management and indexing methods used in existing conventional database management systems are not appropriate for the object-oriented database management systems due to the distinctive features of the later systems. A model for storage management suitable for object- oriented database management systems is proposed in this thesis. It supports object identity, multiple inheritance, composite objects, a fine degree of granularity and schema evolution. An index provides fast access to data stored in files at the price of using additional storage space and an overhead in update operations. Work has been carried out on indexing and an indexing method for the object-oriented database systems is proposed. Identity and equality indexes are treated. Object identity and information hiding are provided. Schema changes are handled without affecting existing indexes. It is general enough to be applicable to most existing object-oriented database systems. The mapping of the proposed storage and indexing approaches into a relational database scheme is also presented.Al-Hajj, RedaM.S

USING DATA BASE MANAGEMENT SYSTEMS IN STATISTICAL DATA PROCESSING

National and international statistical bureaus produce ca. 25,000 tables for publication each year, based on hundreds of inter-related object-types with thousands of attributes. It would appear that this environment should be well suited to the application of data base management techniques for the administration of the data. This paper presents a data oriented model of the statistical production process which is used as a basis for a review of the state of experience within statistical offices with commercially available data base management systems. We conclude with a presentation of some important data management facilities which must be enhanced or developed in order to support statistical production processing.Information Systems Working Papers Serie

Event Indexing Systems for Efficient Selection and Analysis of HERA Data

The design and implementation of two software systems introduced to improve the efficiency of offline analysis of event data taken with the ZEUS Detector at the HERA electron-proton collider at DESY are presented. Two different approaches were made, one using a set of event directories and the other using a tag database based on a commercial object-oriented database management system. These are described and compared. Both systems provide quick direct access to individual collision events in a sequential data store of several terabytes, and they both considerably improve the event analysis efficiency. In particular the tag database provides a very flexible selection mechanism and can dramatically reduce the computing time needed to extract small subsamples from the total event sample. Gains as large as a factor 20 have been obtained.Comment: Accepted for publication in Computer Physics Communication

ARGES: an Expert System for Fault Diagnosis Within Space-Based ECLS Systems

ARGES (Atmospheric Revitalization Group Expert System) is a demonstration prototype expert system for fault management for the Solid Amine, Water Desorbed (SAWD) CO2 removal assembly, associated with the Environmental Control and Life Support (ECLS) System. ARGES monitors and reduces data in real time from either the SAWD controller or a simulation of the SAWD assembly. It can detect gradual degradations or predict failures. This allows graceful shutdown and scheduled maintenance, which reduces crew maintenance overhead. Status and fault information is presented in a user interface that simulates what would be seen by a crewperson. The user interface employs animated color graphics and an object oriented approach to provide detailed status information, fault identification, and explanation of reasoning in a rapidly assimulated manner. In addition, ARGES recommends possible courses of action for predicted and actual faults. ARGES is seen as a forerunner of AI-based fault management systems for manned space systems

A first approach on modelling staff proactiveness in retail simulation models

There has been a noticeable shift in the relative composition of the industry in the developed countries in recent years; manufacturing is decreasing while the service sector is becoming more important. However, currently most simulation models for investigating service systems are still built in the same way as manufacturing simulation models, using a process-oriented world view, i.e. they model the flow of passive entities through a system. These kinds of models allow studying aspects of operational management but are not well suited for studying the dynamics that appear in service systems due to human behaviour. For these kinds of studies we require tools that allow modelling the system and entities using an object-oriented world view, where intelligent objects serve as abstract “actors” that are goal directed and can behave proactively. In our work we combine process-oriented discrete event simulation modelling and object-oriented agent based simulation modelling to investigate the impact of people management practices on retail productivity. In this paper, we reveal in a series of experiments what impact considering proactivity can have on the output accuracy of simulation models of human centric systems. The model and data we use for this investigation are based on a case study in a UK department store. We show that considering proactivity positively influences the validity of these kinds of models and therefore allows analysts to make better recommendations regarding strategies to apply people management practises