The paper shows our experience in developing a trunking radiotelephone network information system using object-oriented technologies. The developed information system has the network management responsibility and it o...
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The paper shows our experience in developing a trunking radiotelephone network information system using object-oriented technologies. The developed information system has the network management responsibility and it offers a complete set of utilities to the network operator to facilitate its work. It has been necessary to balance requirements from the management point of view (real-time interaction, statistics, etc.), requirements from the technical connection with the network (different technologies, buffering problems, etc.), and extra requirements imposed by the client (remote management option, easy to platform migration, etc.). Representation techniques based on object meta-knowledge have been used as a powerful tool to provide a flexible and easy to extend mechanism to cover application design and implementation phases. The adopted architecture and the main components and their orchestration are described. This paper includes learned experiences, development criteria, problems and choices of commercial products.
Multicast (group) communications have been widely recognized by current research and industry. Multicast is very useful for various network applications such as distributed (replicated) database, video/audio conferenc...
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Multicast (group) communications have been widely recognized by current research and industry. Multicast is very useful for various network applications such as distributed (replicated) database, video/audio conference, information distribution and server locations etc. But design and implementation of such multicast communication systems in networks are complicated tasks, especially when quality of services (QoS) of applications such as real-time and reliability are desired. To quick design and implement multicast communication, good tools are crucial and must be facilitated. This paper presents a novel object-oriented (O-O) QoS driven approach for the quick design and prototyping of multicast communication systems under certain QoS requirements for multicast message transmission and receptions such as real-time, total ordering, atomicity and fault-tolerance etc.
One major approach to realise database integration is to adapt and merge the database schemas by defining views. When integrating object-oriented databases, the views need to adequately support object identity and met...
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One major approach to realise database integration is to adapt and merge the database schemas by defining views. When integrating object-oriented databases, the views need to adequately support object identity and methods. View objects need to be identified on the basis of the objects they have been derived from. Methods must be callable from the query processor without impeding query optimisation. Our view system for ODMG-93 supports both declarative and procedural integration of object-oriented databases. It provides flexible integration semantics without sacrificing the optimisation potential.
In this article, we advocate the use of application-type and computation-paradigm specific, as opposed to general purpose, analysis and design methodologies for developing software systems. To motivate and justify thi...
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In this article, we advocate the use of application-type and computation-paradigm specific, as opposed to general purpose, analysis and design methodologies for developing software systems. To motivate and justify this viewpoint, we describe an object-oriented analysis and design methodology that is tailored for software systems whose functionality is to be implemented mainly through database operations. Because business information systems are typically in this category, the methodology is given the name Business object-oriented Analysis and Design methodology, or BOOAD for short. The notation, as well as the semantics of the notation used in BOOAD, is inherited from the object Modeling Technique (OMT) of Rumbaugh, but somewhat modified through the lifting up of various notions from the object-oriented database systems. These modifications include, among others, the concept of considering classes as repositories of objects, having classes answer queries regarding the objects they contain, the concept of a transaction that can be rolled back if necessary, integrity constraints on the states of objects, and set-valued and pointer-valued attributes of objects, as well as an exception mechanism that provides support for error handling and error recovery. object communication is mainly through events in the broadcast-receive mode, but point-to-point communication among objects and classes is also supported. A sample analysis model (student registration system) is developed to demonstrate the main concepts of BOOAD.
object-oriented application frameworks present one of the most successful approaches to developing reusable assets in industry, but developing frameworks is both difficult and expensive. Frameworks generally evolve th...
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object-oriented application frameworks present one of the most successful approaches to developing reusable assets in industry, but developing frameworks is both difficult and expensive. Frameworks generally evolve through a number of iterations due to the incorporation of new requirements and better domain understanding. Since changes to frameworks have a large impact on the applications build based on the asset, it is important to assess the stability of a framework. Recently, an approach for assessing framework stability has been proposed. We have extended and applied the assessment approach on one proprietary telecommunication framework and two commercial GUI application frameworks. Based on our findings we formulate a set of hypotheses, which characterize the stability of an object-oriented application framework. We believe these hypotheses to be the most promising ones for further studies of framework stability.
object-oriented frameworks are established tools for domain-specific reuse. Many framework design patterns have been documented, e.g. reverse engineering framework architectures from conventionally built applications ...
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object-oriented frameworks are established tools for domain-specific reuse. Many framework design patterns have been documented, e.g. reverse engineering framework architectures from conventionally built applications for a given domain. The framework development cycle generally evolves from open framework to closed application. We describe a more flexible component-based approach to framework design that stresses a common interface for `plugging-in' new components at different lifecycle stages. An analysis of framework-related user roles shows that the classical developer/end-user boundary is too rigid. We see the framework's development as a continuum within which its `actors' can customize its behaviour. This both increases the system's flexibility and reduces its maintenance requirement. A case study of three frameworks for different application domains illustrates the presented principles.
Visual modeling languages are appealing because `a picture tells more than a thousand words'. The UML is such a visual language and is well known for its graphical notation and diagramming techniques. However, pic...
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Visual modeling languages are appealing because `a picture tells more than a thousand words'. The UML is such a visual language and is well known for its graphical notation and diagramming techniques. However, pictures often only tell half of the story and additional information needs to be captured in a different way. For this reason the UML includes the object Constraint Language (OCL), a textual language which allows a UML modeler to specify these additional constraints. This tutorial shows the importance of constraints as an object-oriented modeling technique and how they add value to the visual modeling techniques and help `telling the complete story'. The OCL language itself and the connection with the visual UML diagrams is thoroughly explained. The final part of the tutorial will show how one can achieve a good balance between the visual and constraint modeling in UML.
The current fashion in database technology is the eschewing of relational databases in favor of object-oriented databases. C.J. Date and Hugh Darwen (1995) have issued a challenge for the industry to turn away from to...
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The current fashion in database technology is the eschewing of relational databases in favor of object-oriented databases. C.J. Date and Hugh Darwen (1995) have issued a challenge for the industry to turn away from today's relational database products and to begin to develop and use databases conforming to the formal relational model. To meet the storage requirements of modern data, they propose to extend the notion of domains, and they claim that this expanded notion, when combined with the formal relational model, would be more than sufficient for the vast majority of the applications now being moved to object-oriented databases. This paper makes a brief survey of the relational model, object orientation in programming, and some of the present attempts to combine the two. It then presents ORR, a prototype implementation of a database system that incorporates a version of the expanded notion of domains into a near relational database.
object oriented programming techniques make it possible for accelerator designers to independently develop C++ software components that can work together. As an example of this approach, we discuss some of the softwar...
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object oriented programming techniques make it possible for accelerator designers to independently develop C++ software components that can work together. As an example of this approach, we discuss some of the software components being developed at Tech-X Corporation, including: TxSTD, a library of standard utilities; TxID, a library of data-holding and nonlinear dynamics classes; TxAC, an accelerator modeling class library; an X/Motif library used in the MAPA application for interactive visualisation of dynamical systems such as particle accelerators; TxAN, a library of analysis and simulation classes relevant to dynamical systems; and the LION++ nonlinear optimization library.
This paper describes the authors' experiences in using the multiparadigm language GED to teach the principles of a programming languages course. The benefits of using a multiparadigm language include less time spe...
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This paper describes the authors' experiences in using the multiparadigm language GED to teach the principles of a programming languages course. The benefits of using a multiparadigm language include less time spent on learning new environments for different languages, easier transition to different paradigms, and opportunities for multiparadigm programming. In this paper, they give a brief description of GED (which supports the imperative, functional, logic and object-oriented paradigms), describe how it is used in their course, and discuss the advantages and disadvantages of this approach versus the traditional use of several languages.
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