Lidia Fuentes

DAOP-ADL: an architecture description language for dynamic component and aspect-based development

Architecture description languages deal with the description, analysis and reuse of software architectures. This paper describes DAOP-ADL, a component- and aspect-based language to specify the architecture of an application in terms of components, aspects and a set of plug-compatibility rules between them. With the aim of connecting the specification of the application architecture to the implementation, we describe our language using XML and XML Schemas. The DAOP-ADL language was designed to be interpreted by DAOP, our own dynamic component- and aspect-oriented platform. DAOP provides a composition mechanism that plugs aspects into components dynamically at runtime. The software architect will use the DAOP-ADL language at design time to describe the architecture of the application. Later this architectural information is loaded into the DAOP platform, which needs it to establish the dynamic connections between autonomous components and aspects. Therefore, the use of DAOP-ADL closes the gap between design and implementation of component- and aspect-based applications.

A Dynamic Component and Aspect-Oriented Platform

Component-based software development (CBSD) represents a significant advance towards assembling systems by plugging in independent and (re)usable components. On the other hand, aspect-oriented software development (AOSD) is presently considered as a possible technology to improve the modularity and adaptability of complex and large-scale distributed systems. Both are complementary technologies, so it would be helpful to have models that combine them to take advantage of all their mutual benefits. Thus recent research has tried to combine CBSD and AOSD by considering aspects as reusable parts that can be woven and then attached to the individual components. Our contribution to the integration of these technologies is CAM, a new component and aspect model that defines components and aspects as first-order entities, together with a non-intrusive composition mechanism to plug aspects into components. The underlying infrastructure supporting CAM is the dynamic aspect-oriented platform (DAOP), a component and aspect platform that provides the usual services of distributed applications, as well as a composition mechanism to perform the plugging of software aspects into components at runtime.

Adding roles to CORBA objects

Traditional IDLs were defined for describing the services that objects offer, but not those services they require from other objects, nor the relative order in which they expect their methods to be called. Some of the existing proposals try to add protocol information to object interfaces, but most of them fail to do so in a modular way. In this paper we propose an extension of the CORBA IDL that uses a sugared subset of the polyadic /spl pi/-calculus for describing object service protocols, based on the concept of roles. Roles allow the modular specification of the observable behavior of CORBA objects, reducing the complexity of the compatibility tests. Our main aim is the automated checking of protocol interoperability between CORBA objects in open component-based environments, using similar techniques to those used in software architecture description and analysis. In addition, our proposal permits the study of substitutability between CORBA objects, as well as the realization of dynamic compatibility tests during their runtime execution.

Language support for managing variability in architectural models

The effective management and composition of architectural variabilities has long been of importance to product line architects. Architects need to describe how conceptual variabilities are composed and realised through architectural decompositions of a product line. Architecture variabilities need to be described in terms of the chosen design decompositions, which do not often correspond naturally to feature model decompositions. Also, the fine-grained nature of certain architectural variabilities makes it difficult to represent them in a modular fashion, and describe how they are composed across different views. In order to address these issues, this paper presents a variability modelling language (VML), which supports first-class representation of heterogeneous forms of architectural variabilities. The language complements existing architectural modelling approaches for product lines by providing mechanisms to: (i) explicitly reference variation points in multiple architectural views, and (ii) support compositions involving both fine-grained and coarse-grained variabilities in an orthogonal fashion. The completeness and simplicity of VML is assessed through four case studies from different domains.

Separation of coordination in a dynamic aspect oriented framework

Aspect-Oriented Programming separates in a new dimension, named aspect, those features that are spread over different components in a system. In this paper we present a Dynamic AO Framework where software components and aspects are first-order entities composed dynamically at runtime according to the architectural information stored in middleware layer. As an example we describe the coordination aspect, one of the most relevant and useful aspects our approach, essential to develop open distributed systems The main functionality of this aspect is to encapsulate interaction protocol among a set of components.

VML* – a family of languages for variability management in software product lines

Managing variability is a challenging issue in software-product-line engineering. A key part of variability management is the ability to express explicitly the relationship between variability models (expressing the variability in the problem space, for example using feature models) and other artefacts of the product line, for example, requirements models and architecture models. Once these relations have been made explicit, they can be used for a number of purposes, most importantly for product derivation, but also for the generation of trace links or for checking the consistency of a product-line architecture. This paper bootstraps techniques from product-line engineering to produce a family of languages for variability management for easing the creation of new members of the family of languages. We show that developing such language families is feasible and demonstrate the flexibility of our language family by applying it to the development of two variability-management languages.

AO-ADL: an ADL for describing aspect-oriented architectures

Architecture description languages are a sound and convenient approach to software architecture representation. The majority of well-known ADLs provide separation of computation and communication in components and connectors, respectively. However, computation and communication are not the only crosscutting concerns that may appear in a software architecture description. Traditional ADLs do not normally provide appropriate support to separate any kind of crosscutting concerns, which frequently result in poor architectures descriptions with highly coupled components. In this paper we present the AO-ADL language, based on a symmetric decomposition model that considers components and connectors as the basic structural elements (similar to traditional ADLs). We will show how aspects are treated as specific types of components that are composed by means of connectors. In order to cope with the separation of concerns we enrich the semantic and expressivity of traditional connectors to support either aspectual and nonaspectual component interactions.

Designing and Weaving Aspect-Oriented Executable UML Models.

Aspect-Oriented technologies, including Aspect-Oriented Modelling, provide a set of new constructs (e.g., advices or pointcuts), that help to improve the modularisation of crosscutting concerns. However, these new constructions can make it more difficult to understand how a system works as a whole, once all design modules are composed together, because: (1) designers may not be familiar with the new aspect-oriented constructions; and/or (2) aspect-orientation may cause new problems, such as the handling of aspect interactions. A straightforward and simple solution to check how a system works is to execute it. UML and its Action Semantics provide the foundations for modelling and executing object-oriented software systems. This paper presents a UML 2.0 Profile which extends the UML and its Action Semantics for the construction of aspect-oriented executable models and also a model weaver which makes the execution of such models possible. Our approach is illustrated using an Online Book Store system taken from the literature.

Extending CORBA Interfaces with Protocols

Traditional IDLs were defined for describing the services that objects offer, but not those services they require from other objects, nor the relative order in which they expect their methods to be called. In this paper we propose an extension of the Common Object Request Broker Architecture (CORBA) interface description language (IDL) that uses a sugared subset of the polyadic π-calculus for describing object service protocols, aimed at the automated checking of protocol interoperability between CORBA objects in open component-based environments. In addition, some advantages and disadvantages of our proposal are discussed, as well as some of the practical limitations encountered when trying to implement and use this sort of IDL extension in open systems.

FamiWare: a family of event-based middleware for ambient intelligence

Most of the middlewares currently available focus on one type of device (e.g., TinyOS sensors) and/or are designed with one requirement in mind (e.g., data management). This is an important limitation since most of the AmI applications work with several devices (such as sensors, smartphones or PDAs) and use a high diversity of low-level services. Ideally, the middleware should provide a single interface for accessing all those services able to work in heterogeneous devices. To address this issue, we propose a family of configurable middleware (FamiWare) with a really flexible architecture, instead of building a single version of a middleware with a rigid structure. In this work, we present the architecture of our middleware that can be configured, following a Software Product Line approach, in order to be instantiated in a particular device fulfilling specific application requirements. Furthermore, we evaluate that the decisions taken at architecture and implementation are the adequate ones for this kind of constrained devices.