A design pattern approach to bitemporal data modeling

The importance of patterns in constructing complex systems has long been recognised in other disciplines. In software engineering, for example, well-crafted object-oriented architectures contain several design patterns. Focusing on mechanisms of constructing software during system development can yield an architecture that is simpler, clearer and more understandable than if design patterns were ignored or not properly applied. In this paper, we propose a model that uses object-oriented design patterns to develop a core bitemporal conceptual model. We define three core design patterns that form a core bitemporal conceptual model of a typical bitemporal object. Our framework is known as the Bitemporal Object, State and Event Modelling Approach (BOSEMA) and the resulting core model is known as a Bitemporal Object, State and Event (BOSE) model. Using this approach, we demonstrate that we can enrich data modelling by using well known design patterns which can help designers to build complex models of bitemporal databases.

Esperimenti di design pattern di ispirazione biologica

L'informatica, assieme alle sue innovazioni tecnologiche, offre al mondo d'oggi uno scenario in continuo sviluppo evolutivo che permette di facilitare alcune necessità dell'essere umano. Con la nascita di internet e dei nuovi dispositivi cellulari, la comunicazione è stata resa più malleabile e immediata. Tuttavia, le nuove tecnologie utilizzano infrastrutture complesse che non sempre sono ampiamente sfruttate a causa delle loro esigenze quali scalabilità, risposte in tempo reale, o tolleranza. Per far fronte a queste caratteristiche, una nuova tendenza del software è quella di fornire autonomia e pro-attività alle entità nel sistema in modo da incrementare la loro interazione. Queste caratteristiche permettono di responsabilizzare i soggetti rendendo il sistema auto-organizzato, con una migliore scalabilità,robustezza, e quindi riducendo le esigenze di calcolo di ciascuna entità. Lo studio dei sistemi auto-organizzanti è stato ispirato alla natura, e in particolare, ai sistemi biologici. Questi sistemi mostrano le caratteristiche interessanti per gli scenari pervasivi, poichè sono robusti e resistenti, in grado di adattarsi al contesto ambientale e quindi reagiscono a determinate modifiche che si verificano nell'ambiente comportandosi di conseguenza. L'ingegneria dell'auto-organizzazione ha il compito di simulare e testare questi comportamenti presentando uno schema progettuale completo che permetta di presentare soluzioni ricorrenti a problemi noti. Tale schema è definito in termini informatici design pattern. Le entità, definite agenti, per interagire e comunicare tra di loro hanno bisogno di coordinarsi tramite un modello specifico. Nel nostro caso è stato scelto TuCSoN, poichè riesce a separare uno spazio dedicato allo scambio di informazioni da uno spazio dedicato alle specifiche che permette di descrivere delle politiche di comportamento per sistemi MAS implementati nell'opportuno linguaggio di programmazione ReSpecT.

A design pattern for efficient retrieval of large data sets from remote data sources

Retrieving large amounts of information over wide area networks, including the Internet, is problematic due to issues arising from latency of response, lack of direct memory access to data serving resources, and fault tolerance. This paper describes a design pattern for solving the issues of handling results from queries that return large amounts of data. Typically these queries would be made by a client process across a wide area network (or Internet), with one or more middle-tiers, to a relational database residing on a remote server. The solution involves implementing a combination of data retrieval strategies, including the use of iterators for traversing data sets and providing an appropriate level of abstraction to the client, double-buffering of data subsets, multi-threaded data retrieval, and query slicing. This design has recently been implemented and incorporated into the framework of a commercial software product developed at Oracle Corporation.

Expertise in software design : novice and expert models

This paper investigates how software designers use their knowledge during the design process. The research is based on the analysis of the observational and verbal data from three software design teams generated during the conceptual stage of the design process. The knowledge captured from the analysis of the mapped design team data is utilized to generate descriptive models of novice and expert designers. These models contribute to a better understanding of the connections between, and integration of, designer variables, and to a better understanding of software design expertise and its development. The models are transferable to other domains.

Supporting Reuse and Evolution in Software Design

Program design is an area of programming that can benefit significantly from machine-mediated assistance. A proposed tool, called the Design Apprentice (DA), can assist a programmer in the detailed design of programs. The DA supports software reuse through a library of commonly-used algorithmic fragments, or cliches, that codifies standard programming. The cliche library enables the programmer to describe the design of a program concisely. The DA can detect some kinds of inconsistencies and incompleteness in program descriptions. It automates detailed design by automatically selecting appropriate algorithms and data structures. It supports the evolution of program designs by keeping explicit dependencies between the design decisions made. These capabilities of the DA are underlaid bya model of programming, called programming by successive elaboration, which mimics the way programmers interact. Programming by successive elaboration is characterized by the use of breadth-first exposition of layered program descriptions and the successive modifications of descriptions. A scenario is presented to illustrate the concept of the DA. Technques for automating the detailed design process are described. A framework is given in which designs are incrementally augmented and modified by a succession of design steps. A library of cliches and a suite of design steps needed to support the scenario are presented.

Applying CBR to measure similarity of software design structures

This paper examines different ways for measuring similarity between software design models for the purpose of software reuse. Current approaches to this problem are discussed and a set of suitable similarity metrics are proposed and evaluated. Work on the optimisation of weights to increase the competence of a CBR system is presented. A graph matching algorithm and associated metrics capturing the structural similarity between UML class diagrams is presented and demonstrated through an example case.