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Asynchronous data retrieval from an object-oriented database
We present an object-oriented semantic database model which, similar to other object-oriented systems, combines the virtues of four concepts: the functional data model, a property inheritance hierarchy, abstract data types and message-driven computation. The main emphasis is on the last of these four concepts. We describe generic procedures that permit queries to be processed in a purely message-driven manner. A database is represented as a network of nodes and directed arcs, in which each node is a logical processing element, capable of communicating with other nodes by exchanging messages. This eliminates the need for shared memory and for centralized control during query processing. Hence, the model is suitable for implementation on a multiprocessor computer architecture, consisting of large numbers of loosely coupled processing elements
Semantics Through Pictures: towards a diagrammatic semantics for object-oriented modelling notations
An object-oriented (OO) model has a static component, the set of allowable snapshots or system states, and a dynamic component, the set of filmstrips or sequences of snapshots. Diagrammatic notations, such as those in UML, each places constraints on the static and/or dynamic models. A formal semantics of OO modeling notations can be constructed by providing a formal description of (i) sets of snapshots and filmstrips, (ii) constraints on those sets, and (iii) the derivation of those constraints from diagrammatic notations. In addition, since constraints are contributed by many diagrams for the same model, a way of doing this compositionally is desirable. One approach to the semantics is to use first-order logic for (i) and (ii), and theory inclusion with renaming, as in Larch, to characterize composition. A common approach to (iii) is to bootstrap: provide a semantics for a kernel of the notation and then use the kernel to give a semantics to the other notations. This only works if a kernel which is sufficiently expressive can be identified, and this is not the case for UML. However, we have developed a diagrammatic notation, dubbed constraint diagrams, which seems capable of expressing most if not all static and dynamic constraints, and it is proposed that this be used to give a diagrammatic semantics to OO models
A Formal ORM-to -UML Mapping Algorithm
The object-role model (ORM) data structure can be represented in the unified modeling language (UML) using the five fact encoding constructs: class attribute, association, association class, sub-class and the association qualifier. In the existing literature there exist numerous mappings of how individual fact types from an ORM information model can be mapped onto âwell-formedâ UML expressions. What is lacking in the existing literature is a precise description of the conditions on the âsourceâ object-role model under which a specific UML fact encoding construct can be applied in the âtargetâ UML class diagram. In this paper we will show under what conditions, a specific UML fact encoding construct must be applied in a way that results in a well-formed UML class diagram.computer science applications;
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
Automating the Object-Oriented Software Development Process: Workshop Report
Cost-effective realization of robust, adaptable and reusable software systems demands efficient and effective management of the overall software production process. Current object-oriented methods are not completely formalized and lack the ability of reasoning about the quality of processes and software products (artifacts). There is a need for new modeling formalisms, which enable the quantification of the required quality attributes and support the automation of the object-oriented development process (AOOSD). The ECOOP'98 AOOSD workshop was organized to identify the important issues in this direction
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