87,283 research outputs found
UML Class Diagram or Entity Relationship Diagram : An Object Relational Impedance Mismatch
It is now nearly 30 years since Peter Chenâs watershed paper âThe Entity-Relationship Model âtowards a Unified View of Dataâ. [1] The entity relationship model and variations and extensions to ithave been taught in colleges and universities for many years. In his original paper Peter Chen looked at converting his new ER model to the then existing data structure diagrams for the Network model. In recent years there has been a tendency to use a Unified Modelling Language (UML) class diagram forconceptual modeling for relational databases, and several popular course text books use UMLnotation to some degree [2] [3]. However Object and Relational technology are based on different paradigms. In the paper we argue that the UML class diagram is more of a logical model (implementation specific). ER Diagrams on theother hand, are at a conceptual level of database design dealing with the main items and their relationships and not with implementation specific detail. UML focuses on OOAD (Object Oriented Analysis and Design) and is navigational and program dependent whereas the relational model is set based and exhibits data independence. The ER model provides a well-established set of mapping rules for mapping to a relational model. In this paper we look specifically at the areas which can cause problems for the novice databasedesigner due to this conceptual mismatch of two different paradigms. Firstly, transferring the mapping of a weak entity from an Entity Relationship model to UML and secondly the representation of structural constraints between objects. We look at the mixture of notations which students mistakenly use when modeling. This is often the result of different notations being used on different courses throughout their degree. Several of the popular text books at the moment use either a variation of ER,UML, or both for teaching database modeling. At the moment if a student picks up a text book they could be faced with either; one of the many ER variations, UML, UML and a variation of ER both covered separately, or UML and ER merged together. We regard this problem as a conceptual impedance mismatch. This problem is documented in [21] who have produced a catalogue of impedance mismatch problems between object-relational and relational paradigms. We regard the problems of using UML class diagrams for relational database design as a conceptual impedance mismatch as the Entity Relationship model does not have the structures in the model to deal with Object Oriented concepts Keywords: EERD, UML Class Diagram, Relational Database Design, Structural Constraints, relational and object database impedance mismatch. The ER model was originally put forward by Chen [1] and subsequently extensions have been added to add further semantics to the original model; mainly the concepts of specialisation, generalisation and aggregation. In this paper we refer to an Entity-Relationship model (ER) as the basic model and an extended or enhanced entity-relationship model (EER) as a model which includes the extra concepts. The ER and EER models are also often used to aid communication between the designer and the user at the requirements analysis stage. In this paper when we use the term âconceptual modelâ we mean a model that is not implementation specific.ISBN: 978-84-616-3847-5 3594Peer reviewe
From Method Fragments to Method Services
In Method Engineering (ME) science, the key issue is the consideration of
information system development methods as fragments. Numerous ME approaches
have produced several definitions of method parts. Different in nature, these
fragments have nevertheless some common disadvantages: lack of implementation
tools, insufficient standardization effort, and so on. On the whole, the
observed drawbacks are related to the shortage of usage orientation. We have
proceeded to an in-depth analysis of existing method fragments within a
comparison framework in order to identify their drawbacks. We suggest
overcoming them by an improvement of the ?method service? concept. In this
paper, the method service is defined through the service paradigm applied to a
specific method fragment ? chunk. A discussion on the possibility to develop a
unique representation of method fragment completes our contribution
Formal specification techniques in object-oriented analysis: a comparative view.
During the last decade, object orientation has been advanced as a promising paradigm for software construction. In addition several authors have advocated the use of formal specification techniques during software development. Formal methods enable reasoning (in a mathematical sense) about properties of programs and systems. It is clear that also object oriented software development can benefit from the use of formal techniques.But although the object oriented analysis (OOA) methods claim to provide the necessary concepts and tools to improve the quality of software development, they are in general informal. This is surprising as the modeling techniques used in OOA have a high potential for formalization. The purpose of this study is to compare the specification techniques used in current OOA-methods. In particular, the degree of formality provided by most of the methods is discussed and evaluated from a quality control perspective.Software; Methods; Programs; Systems; Studies; Quality control;
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Computerization of workflows, guidelines and care pathways: a review of implementation challenges for process-oriented health information systems
There is a need to integrate the various theoretical frameworks and formalisms for modeling clinical guidelines, workflows, and pathways, in order to move beyond providing support for individual clinical decisions and toward the provision of process-oriented, patient-centered, health information systems (HIS). In this review, we analyze the challenges in developing process-oriented HIS that formally model guidelines, workflows, and care pathways. A qualitative meta-synthesis was performed on studies published in English between 1995 and 2010 that addressed the modeling process and reported the exposition of a new methodology, model, system implementation, or system architecture. Thematic analysis, principal component analysis (PCA) and data visualisation techniques were used to identify and cluster the underlying implementation âchallengeâ themes. One hundred and eight relevant studies were selected for review. Twenty-five underlying âchallengeâ themes were identified. These were clustered into 10 distinct groups, from which a conceptual model of the implementation process was developed. We found that the development of systems supporting individual clinical decisions is evolving toward the implementation of adaptable care pathways on the semantic web, incorporating formal, clinical, and organizational ontologies, and the use of workflow management systems. These architectures now need to be implemented and evaluated on a wider scale within clinical settings
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