Abstract
Over the last decade, software architecture emerged as a critical issue in Software Engineering. This encompassed a shift from traditional programming towards software development based on the deployment and assembly of independent components. The specification of both the overall systems structure and the interaction patterns between their components gbecame a major concern for the working developer. Although a number of formalisms to express behaviour and to supply the indispensable calculational power to reason about designs, are available, the task of deriving architectural designs on top of popular component platforms has remained largely informal. This paper introduces a systematic approach to derive, from CCS behavioural specifications the corresponding architectural skeletons in the Microsoft. Net framework, in the form of executable C# and C? code. The prototyping process is fully supported by a specific tool developed in Haskell.

Abstract
This paper introduces a generic semantic framework for component-based development, expressed in the unified modelling language UML. The principles of a coalgebraic semantics for class, object and statechart diagrams as well as for use cases, are developed. It is also discussed how to formalize the refinement steps in the development process based upon a suitable notion of behavior refinement. In this way, a formal basis for component-based development in UML is studied, which allows the construction of more complex and specific systems from independent components. © 2005 Published by Elsevier B.V.

Abstract
This paper provides an overview of an approach to coalgebraic modelling and refinement of state-based software components, summing up some basic results and introducing a discussion on the interplay between behavioural and classical data refinement. The approach builds on coalgebra theory as a suitable tool to capture observational semantics and to base an abstract characterisation of possible behaviour models for components (from partiality to different degrees of non-determinism).

Abstract
Although increasingly popular, software component techniques still lack suitable formal foundations on top of which rigorous methodologies for the description and analysis of software architectures could be built. This paper aims to contribute in this direction: building on previous work by the authors on coalgebraic semantics, it discusses component refinement at three different but interrelated levels: behavioural, syntactic, i.e., relative to component interfaces, and architectural. Software architectures are defined through component aggregation. On the other hand, such aggregations, no matter how large and complex they are, can also be dealt with as components themselves, which paves the way to a discipline of hierarchical design. In this context, a major contribution of this paper is the introduction of a set of rules for architectural refinement.

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