List of Presentations

Koetter Hans-Friedrich and Nan Guo, Fern Universitaet Hagen: Automated Request Brokerage using Type-dependent Decisions and Monitoring Agents.

The World Wide Web and Distributed Object-Oriented Systems (like e.g. CORBA) provide foundation and infrastructures for distributed client-server computing. This talk presents our work to integrate CORBA-Objects into the Web through the employment of the software packages OrbixWeb and Orbix. With the programming language JAVA and the CORBA-tool OrbixWeb, we have implemented a graphical frontend which runs on any JAVA platform and allows access to remotely offered services. In our application, brokerage is based on type-dependent decisions. Routing to the most appropriate server is decided dynamically depending on load characteristics of the web-servers and the request-type. The service itself is implemented in C++ and the CORBA-tool Orbix, providing a realistic example of an application of the CORBA language mapping facility.

Full Text (compressed postscript). Complementary Figure (compressed postscript).

Bergner Klaus, Technische Universität München: Casting an Abstract Design into the Framework of Java RMI.

Java's Remote Method Invocation mechanism is an object-oriented middleware framework for the development of distributed applications. We describe our experiences with a case study where we casted an abstract design specification for a small, distributed multi-user editor into the framework of Java RMI. We concentrate on the encountered difficulties and present workarounds for certain problems.

Snoeck Monique, Kath. Univ. Leuven: A proper architecture allows to keep requirements independent from implementation frameworks.

The implementation environment for Information systems is evolving rapidly and often new systems have to coexist and inter-operate with existing legacy systems. This requires a very flexible (adaptable and maintainable) information systems architectures in order to keep the cost of software development manageable. Current OOAD methods do not sufficiently take account for these factors: they are to much focused on the development of new projects where everything is build from scratch. However, an adapted version of the Zachman framework for Information Systems architecture can provide us with interesting guidelines for partitioning and layering specifications such that specifications remain as independent as possible from the choosen implementation environment. In addition it provides concepts for structuring "make or buy" decisions, for the evaluation of "off-the-shelf" software and for the integration of new systems with legacy systems.

Tai Stefan and Wortmann Jan, Technische Univ. Berlin: On the Impact of Integration Platforms on Architecting Air Traffic Control Systems

Integration platforms such as CORBA have the potential to facilitate the implementation of distributed applications, since tedious network programming can be avoided. The platform technology and especially its object model however impact design decisions and such must be recorded in the software architecture. In this paper we regard as an example the air traffic control domain and discuss the benefits of using software architectural abstractions of components and connectors to better cope with system evolution.

Kurki Tiina, TT Tieto Oy, Finland: Application of object-based CASE-Tools in systems development process (ESSI Process Improvement Project, project "FI-TOOLS", ESSI number: 21367).

Excerpt from project report (main conclusions): When using an object-oriented CASE-tool from methodological point of view, the CASE-tool builds a connection between design and implementation phases of the project. The personnel in Banking and Financial systems has become aware of component libraries. This is a remarkable point both from the business and technical point of view in the longer run. When we are producing new components it is crucial for the further use of the components, that they are very well tested.

Project Report.

Rivett-Carnac John Ainsworth and Assoc., UK. Experience Report.

Raghavan Sri, Digital, U.S.A.: [title].


Keller Rudolf, University of Montreal, Canada: Middleware for Software Design.

Abstract component software models promote software development by assembly of prefabricated, configurable, and independently evolving building blocks. Although effective for systems implementation, this approach is inadequate for the creation of reusable and changeable software architectures. Architectural design is an evolutionary process that requires abstract thinking and expertise in both the application domain and software design. Successful software architectures usually arise from a continuous reassessment of design alternatives and redistribution of responsibilities. Design patterns address exactly these shortcomings of component-based software development. They capture the formal and informal expertise that is necessary for a reusable solution to a recurring problem. Thus, design patterns become the conceptual building blocks for software development. However, so far there is no methodical approach to providing these building blocks in a tangible, flexible, and composable form. To address this shortcoming, we introduce design components, reified design patterns fit for component software. Design components allow for an incremental evolution and iterative refinement of software, beginning with architectural design and ending with the executable application. Design components can be abstract or concrete, generic or domain-specific, basic or composite, and incorporate both the formal design pattern structure and informal design expertise, such as applicability and trade-offs. They are modeled using extended techniques of object modeling languages, such as the UML. Most importantly, they exhibit a clear interface and are formal enough to allow for computer-supported composition, customization, storage, and retrieval. They can be considered as middleware for software design. In this talk, we coin and explore the notion of design component and apply it to a case study.

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