D. Tsichritzis, editor. Object Oriented Development. Centre Universitaire d'Informatique, Geneva, Switzerland, July 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....are particularly useful for the construction of so called open systems. There exist various viewpoints on what precisely makes a system open (compare for example [4] with [22] but this discussion lies out of the scope of this article. For our purposes, the following open system requirements[20] are sufficient. 1. Interoperability: Open systems typically run on heterogeneous hardware and software platforms. Platform differences should be encapsulated in the system architecture to ease the integration. 2. Distribution: Open systems are often physically distributed. Coordinating ....

Tsichritzis, D. (Ed.), Object Composition. Centre Universitaire d'Informatique, University of Geneva, June 1991.

....class to be merged has relationships with other classes. Thus, if the invariants properties of the inheritance hierarchy cannot be preserved, the operation that breaks schema consistency rules should be rejected 5 . We chose schema evolution taxonomy of ORION data model based on the 5 Refer [6] for more about schema invariants. comparisons in [6] Table 1 shows the taxonomy of schema modifications in an object oriented database and their corresponding schema construction operations. It means that we can map the consistency problems by our schema construction operations into schema ....

....Thus, if the invariants properties of the inheritance hierarchy cannot be preserved, the operation that breaks schema consistency rules should be rejected 5 . We chose schema evolution taxonomy of ORION data model based on the 5 Refer [6] for more about schema invariants. comparisons in [6]. Table 1 shows the taxonomy of schema modifications in an object oriented database and their corresponding schema construction operations. It means that we can map the consistency problems by our schema construction operations into schema modification problems. Because we did not consider the ....

Tsichritzis, D., ed.: Object Management. Centre Universitaire d'Informatique, University of Geneva (1990)

....between objects and components were not preserved explicitly. The study in progress addresses architectural issues to arrive at explicit reuse mechanisms that preserves the visibility between objects and components. The architectural style followed is similar in some respects to the work by [1, 41, 32, 37, 19]. The aim of this research study is to look at the resource allocation problem more formally to arrive at a mixture of objective and subjective measures. The research is an attempt to develop two architectures models solutions as outlined in section 3. The resulting architectures will be analysed ....

Tsichritzis, D., Nierstrasz, O., and Gibbs, S. Beyond Objects: Objects. Centre Universitaire d'Informatique, Universite de Geneve, 1992, pp. 331--346.

....in, say, deriving the quality of service (QOS) requirements of some application framework. The purpose of this paper is to address the above issues; however, unlike most of the other approaches that are primarily based on imperative programming techniques and the use of languages such as C ([21,22]) or real time ones ( 2] such as ESTEREL ( 8,15] our model is based on declarative programming and, in particular, that of concurrent constraint programming. More to the point, we show how the timed version ( 18] of concurrent constraint programming ( 17] can be used to model and support the ....

....contains a number of multimedia objects, each encapsulating the behaviour and synchronisation of some medium. The behaviours of simple media objects are usually composed to form composite multimedia objects. Our object oriented framework is a variant of Gibb s active objects metaphor ([22]) and is based on the actor model and objectoriented concurrent logic programming techniques. 3. Multimedia Object Synchronisation By synchronisation in the context of programming multimedia applications we usually refer to the need for expressing the temporal behaviour of a media object both with ....

D. Tsichritzis (ed.), Visual Objects, Internal Report (collected papers), Centre Universitaire d'Informatique, Université de Genève, Switzerland, 1992.

....in, say, deriving the quality of service (QOS) requirements of some application framework. The purpose of this paper is to address the above issues; however, unlike most of the other approaches that are primarily based on imperative programming techniques and the use of languages such as C ([21,22]) or real time ones ( 2] such as ESTEREL ( 8,15] our model is based on declarative programming and, in particular, that of concurrent constraint programming. More to the point, we show how the timed version ( 18] of concurrent constraint programming ( 17] can be used to model and support the ....

.... multimedia object synchronisation, especially due to the fact that a certain time delay can be tolerated (thus, placing multimedia systems in the category of soft real time systems) In particular, for any (composite) multimedia object C the following formula should hold for all its components Ci ([21]) C.current world time Ci.current world time Di where Di is the synchronisation tolerance for every component Ci. A certain synchronisation tolerance is also expected between two objects M1 and M2 expressed by a similar formula: ObjToWorld(M1.object time) ObjToWorld(M2.object time) ....

D. Tsichritzis (ed.), Object Frameworks, Internal Report (collected papers), Centre Universitaire d'Informatique, Université de Genève, Switzerland, 1992.

....Next the overall architectural design of a system in OM ML is described. We will see how the functional partitioning of the behavioral and the architectural elements of an actor class is established, and how they are made to operate. 3. 1 Actors and actor classes An actor is an active object [25] [26] which is characterized by a behavior and consists of a number of activities. An actor is an instance of an actor class. An actor class, like any other class on the basis of object oriented paradigm [27] is defined as a template from which objects are created. A template contains a general ....

D. Tsichritzis, editor. Active Object-Environments. Centre Universitaire d'Informatique, University of Geneva, 1987.

....construction of the formal system along with several illustrative examples. 1 Introduction The formal system introduced in this paper is intended to accomplish two purposes. First, it provides a simple and rigorous formalism which encapsulates essential features of concurrent object orientation [26, 25]. Being successful as a programming methodology for dynamic concurrent computing, its theoretical contents are far from well understood, 1 leaving theorists and practitioners without a core theory on which they can reason and develop further ideas. Second, it offers a possible foundation for ....

Tsichritzis, D. (ed.) : Object Management. Centre Universitaire D'informatique, Universite de Geneve, July 1990.

....to be fast [27] 1] compared to the data inquiry and computation time, e.g. by restraining myself to wire frame representations. In contrast, multimedia systems, being based on presampled data types that are inherently wall time based, are aware of sampling rates and real time display of results [40]. Recent work [18] 23] also addresses issues in degrading the data stream in order to stay synchronized to wall time. However, since the involved data types are presampled, thus prespecified and often sampled at regular intervals, there is no need for complex sampling rate models or complex ....

D. Tsichritzis, editor. Visual Objects. Centre Universitaire d'Informatique, Universit'e de Gen`eve, June 1993.

....others. These principles are intended to address both user and methodological needs. For example, similarity links are there because users find it natural to ask for similar components, intended to reflect, however, the ITHACA way of constructing software by scripting together existing classes [Tsic91], shared by other object oriented viewpoints where software composition has replaced the problem decomposition methodologies associated with structured programming. Considering its size, complexity and required investment, effective management of the SIB is obviously critical. The SIB has been ....

Tsichritzis, D. (ed.), Object Composition, Centre Universitaire d' Informatique, Universite de Geneve, 1991.

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D. Tsichritzis, editor. Object Oriented Development. Centre Universitaire d'Informatique, Geneva, Switzerland, July 1989.

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Tsichritzis, D., ed. Object Management. Centre Universitaire D'informatique, Universite de Geneve, July 1990.

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