Pattern reification as the basis for description-driven systems

Abstract

Abstract. 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 elementsfirstly, 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.Keywords: meta-models, system description, UML, design patterns, reflection IntroductionMany approaches have been proposed to address aspects of design and implementation for modern object-oriented systems. Each has its merits and focuses on concerns such as data , which have recognized and begun to address these failings. This paper advocates a design and implementation approach that is systemic (or holistic) in nature, viewing the development of modern object-oriented software from a systems standpoint. The philosophy that has been investigated is based on the systematic capture of the description of systems elements covering multiple views of the system to be designed (including data, process and time views) using familiar techniques. The approach advocated here has been termed description-driven and its underlying patterns are the subject of this paper. Essentially the description-driven approach involves identifying and abstracting the crucial elements (such as items, processes, lifecycles, goals, agents and outcomes) in the system under design and creating high-level descriptions of these elements which are stored, dynamically modified and managed separately from their instances.In the object oriented community well-known design patterns [5] have been named, described and cataloged for reuse by the community as a whole. This approach has enabled us to make use of design patterns that were proven on previous projects and is an example of reuse at the larger grain design level. Our studies have also benefited from the use of frameworks: reusable semicomplete applications that can be specialized to produce custom applications. Frameworks specify reusable architectures for all or part of a system and may include reusable classes, patterns or templates. We note that...

The Deployment of an Enhanced Model-Driven Architecture for Business Process Management

“…Following the principles of OO design the DDS approach encourages reuse of code and scripts/methods. Indeed, the description-driven design approach takes this one step further and provides reuse of meta-data, design patterns [11] and maintenance of items and activities (and their descriptions). Practically this results in a higher level of control over design evolution and simpler implementation of system improvements in addition to simpler maintenance cycles.…”

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“…Every component part was registered as an Item in the CRISTAL database, each with its barcode as an identifier. Each part had a type, which functioned as the Item Description, and was linked to the Workflow definition that each instance would follow in order to collect its data and mount sub-parts (Estrella, 2003). The part types also contained subtype data as Properties and Collection Definitions to make sure that parts were assembled in assigned positions in ECal.…”

CRISTAL-iSE - Provenance Applied in Industry

“…The main concept behind CRISTAL is what is known as a "description driven" system (Estrella, 2003). The main strength of such a "description driven" approach is that users who develop models of systems need only define them once to create a usable application.…”