Highly analysable, reusable, and realisable architectural designs with XCD

Connector-Centric Design (XcD) is a new approach to specifying software architectures. XcD views complex connectors as highly significant in architectural designs, as it is the complex connectors that non-functional quality properties in systems can emanate from. So, XcD promotes in designs a clean separation of connectors (interaction behaviours) from components (functional behaviours). Designers can then specify connectors in detail explicitly thus easing the analysis of system designs for quality properties. Furthermore, XcD separates control behaviour from connectors as control strategies. Architectural designs in XcD thus become highly modular with re-usable components, connectors, and control strategies (representing design solutions for quality properties). The end result is the eased architectural experimentation with different design solutions by re-using components/connectors and formal analysis of these solutions to find out the optimal ones

Software architecture: styles and representational schemes

Software architecture is being widely used today to describe a very high-level design methodology of large software systems. Software architecture represents the overall structure of a system in an abstract, structured manner. A good architectural representation scheme holds the key to the effectiveness of a software architecture description and usage. In this work we look at architectural styles and architectural representation schemes. We propound the idea that the layered architectural model is a suitable candidate for a generalized architectural style and that it can cater to many different problem domains, other than the message-passing systems it has traditionally been used to model. We propose some rules by which the layered architectural style can be improved and modified in order to be able to model a wider problem domain. Then we evaluate different methods of architectural representations that have been used to model software architecture and analyze their strengths and shortcomings. We propose the use of a modified data flow diagram architecture representation scheme. This scheme is called AND-OR DFD method and is introduced and developed in this thesis. The main concept introduced here is a combination of components to form action groups to support multiple workflows and the relationships among them, without significant increase in the architectural complexity. Finally, we look at UML as a prospect for a generalized architecture description language and discuss its merits and demerits with examples

AMBIENT-PRISMA: Distribution and Mobility in Aspect-Oriented Software Architectures

This thesis presents a framework called Ambient-PRISMA for describing and developing distributed and mobile software systems in an abstract way. Ambient-PRISMA enriches an aspect-oriented software architecture approach called PRISMA with concepts of Ambient Calculus (AC). Ambient Calculus (AC) is a formalism that provides primitives to describe distribution and mobility characteristics in an abstract way. It introduces a concept called ambient which is a bounded place where computation happens. This enrichment is performed by extending the PRISMA metamodel, and Aspect-Oriented Architecture Description Language (AOADL). A case study of an electronic Auction System with mobile agents is used throughout the thesis in order to illustrate the work.Ali Irshaid, N. (2007). AMBIENT-PRISMA: Distribution and Mobility in Aspect-Oriented Software Architectures. http://hdl.handle.net/10251/12900Archivo delegad

Model-Driven Development of Aspect-Oriented Software Architectures

The work presented in this thesis of master is an approach that takes advantage of the Model-Driven Development approach for developing aspect-oriented software architectures. A complete MDD support for the PRISMA approach is defined by providing code generation, verification and reusability properties.Pérez Benedí, J. (2007). Model-Driven Development of Aspect-Oriented Software Architectures. http://hdl.handle.net/10251/12451Archivo delegad

Design-by-contract for reusable components and realizable architectures

Architectural connectors can increase the modularity and reusability benefits of Component-based Software Engineering, as they allow one to specify the general case of an interaction pattern and reuse it from then on. At the same time they enable components to be protocol-independent – components do not need to know under which interaction patterns they will be used, as long as their minimal, local interaction constraints are satisfied. Without connectors one can specify only specific instances of such patterns and components need to specify themselves the interaction protocols that they will follow, thus reducing their reusability. Connector frameworks so far allow designers to specify systems that are unrealizable in a decentralized manner, as they allow designers to impose global interaction constraints. These frameworks either ignore the realizability problem altogether, ignore connector behaviour when generating code, or introduce a centralized controller that enforces these global constraints but does so at the price of invalidating any decentralized properties of the architecture. We show how the XCD ADL extends Design-by-Contract (DbC) for specifying (i) protocol-independent components, and (ii) arbitrary connectors that are always realizable in a decentralized manner as specified by an architecture – XCD connectors impose local constraints only. Use of DbC will hopefully make it easier for practitioners to use the language, compared to languages using process algebras. We show how XCD specifications can be translated to ProMeLa so as to verify that (i) provided services local interaction constraints are satisfied, (ii) provided services functional pre-conditions are complete, (iii) there are no race-conditions, (iv) event buffer sizes suffice, and (v) there is no global deadlock. Without formally analyzable architectures errors can remain undiscovered for a long time and cost too much to repair

Top-Down Composition of Software Architectures

This paper discusses an approach for top-down composition of software architectures. First, an architecture is derived that addresses functional requirements only. This architecture contains a number of variability points which are next filled in to address quality concerns. The quality requirements and associated architectural solution fragments are captured in a so-called Feature-Solution (FS) graph. The solution fragments captured in this graph are used to iteratively compose an architecture. Our versatile composition technique allows for pre- and post-refinements, and refinements that involve multiple variability points. In addition, the usage of the FS graph supports Aspect-Oriented Programming (AOP) at the architecture level