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- Bosch, Jan, et al.
(författare)
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Multiple Object Interfaces in Object-Oriented Control Systems
- 1996
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Konferensbidrag (refereegranskat)abstract
- When modelling complex computer systems, four primary modelling techniques are available to the software engineer, i.e. abstraction, composition, functional decomposition and multiple client interfaces (views). Abstraction and composition can directly be expressed in traditional object-oriented models and functional decomposition can often be expressed using subsystems. However, traditional object models provide no expressiveness for multiple client interfaces. This forces designers to either model all different views on a conceptual object as a large, complex implementation object or to model each view as an object and relate the different view objects. Both approaches suffer from problems of complexity, maintainability and reusability. As a solution, we propose the layered object model that allows for the expressive, flexible and extensible definition of multiple client interfaces. To illustrate the problems associated with views and our proposed solution, the domain of industrial control systems is used.
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| 2. |
- Gustavsson, Rune, et al.
(författare)
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Societies of Computation (SoC). A Framework for Open Distributed systems-phase II:1995-98
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The research program Societies of Computation (SoC) at the IDE department of HK/R has been in operation since more than one year [ 11, [2]. The SoC framework takes a Multi Agent System (MAS) approach when addressing issues in open distributed computing. The results so far are very promising and will shortly be outlined below. Assessment of those results combined by results and ideas from the international research society as well as needs from enterprises are background material for our next phase. The goals and expected results from this phase is briefly discussed in following sections. The research group, performing activities in the SoC framework, has been formed during the first phase of the project, and has at present the following active members: Rune Gustavsson, professor and principal investigator, Hans Akkermans, professor at Twente University and guest researcher, Eric Astor, Ph.D., University of Lund, Olle Lindeberg, Ph.L., HK/R, Staffan Hagg, Ph.L., HK/R, Fredrik Ygge, MSc., HK/R and Sydkraft, Barcin Kozbe, M.Sc., Ericsson Infocom Christer Lundberg, M.Sc, University College of Kalmar, Bengt Carlsson, M.Sc., University of Lund Occasionally also other researchers at IDE are involved in shorter R&D activities conducted under the SoC umbrella. Applications developed in SoC have also been sources for several projects performed by undergra-duate students, during the fiscal year of 1994-95 about 12 person years, from several undergraduate programs. Those activities of the SoC program have mainly been performed within the center SIKT. SIKT, Society Information and Knowledge Technologies, is a recently formed center at HK/R. The key industrial partner up to this point has been Sydkraft AB. The project Intelligent Distribution Automation (IDA) at Sydkraft has been a valuable partner for developing applications and assessing results. Ronneby Energi AB (REAB) and Affarsverken i Karlskrona AB are also actively supporting our R&D. The project Communication and Distributed Computing for Efficient Management of Energy Systems, supported by governmental agencies, has been instrumental for introducing and assessing MAS technologies in the Swedish research society as well as to Swedish industry.
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| 3. |
- Lundberg, Christer, et al.
(författare)
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Modelling Causal Connections between Objects
- 1997
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Ingår i: Journal of Programming Languages. - London : Chapman & Hall. - 0963-9306. ; 5:1, s. 233-258
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Tidskriftsartikel (refereegranskat)abstract
- The conventional object-oriented paradigm provides client-server message passing as the primary means of interaction between objects. Although this is appropriate in situations where one objects requests a service from another object, there are other situations where one object, the observer, depends on state-changes or actions occurring at another object, the target. In those situations, the object-oriented paradigm requires the target object to notify the observer objects, despite the fact that the target object does not benefit from the interaction. This inverted interaction scheme leads to problems such as increased coupling and decreased understandability, maintainability and reusability of the resulting classes. In the analysis of object interactions one can identify four roles: the benefitor, the establisher, the sender and the receiver. The aforementioned problems result from the fact that in client-server interaction, the benefitor and the sender are not always the same object. To address this, we pr opose the notion of causal connections, an alternative interaction mechanism complementing the traditional client-server interaction. Two implementations of causal connections are described; one in the context of C++ and another using the layered object model. It is shown that causal connections solve the problems mentioned above.
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