José María Troya

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.

Specifying aspect-oriented architectures in AO-ADL

Abstract Context Architecture description languages (ADLs) are a well-accepted approach to software architecture representation. The majority of well-known ADLs are defined by means of components and connectors. Architectural connectors are mainly used to model interactions among components, specifying component communication and coordination separately. However, there are other properties that cut across several components and also affect component interactions (e.g. security). Objective It seems reasonable therefore to model how such crosscutting properties affect component interactions as part of connectors. Method Using an aspect-oriented approach, the AO-ADL architecture description language extends the classical connector semantics with enough expressiveness to model the influences of such crosscutting properties on component interactions (defined as ‘aspectual compositions’ in connectors). Results This paper describes the AO-ADL language putting special emphasis on the extended connectors used to specify aspectual and non-aspectual compositions between concrete components. The contributions of AO-ADL are validated using concern-oriented metrics available in the literature. Conclusion The measured indicators show that using AO-ADL it is possible to specify more reusable and scalable software architectures.

Putting together web services and compositional software agents

Web services are the newest trend in information technology, being considered the most used alternative for building distributed open systems. Although currently Web services involve a single client-server access, the market is demanding cooperative Web services to provide a global solution. Recently software agents appear as a good option that can cope with the control of Web services composition, obtaining an integral solution. This paper presents an approach to integrate Web services and software agent technologies. The basis of our approach is the use of the component technology for the development of adaptive software agents. Our compositional software agent performs automated software composition based on the flexibility provided by the component orientation, which makes possible to plug Web services into the agent functionality and compose them during the agent interaction.

Towards an aspect-oriented framework in the design of collaborative virtual environments

The increasing complexity in the development of distributed systems has promoted the appearance of new software technologies that complements compositional framework technology providing a high degree of separation of concerns. One of these approaches is aspect-oriented-programming that introduces a new entity, the aspect, to model those features that cut across different components in the system, increasing its extensibility and configurability. Our goal is the application of this new technology to develop an aspect-oriented application framework to construct highly reusable collaborative virtual environments in short time.

Coordinating distributed components on the web: an integrated development environment

Component‐based software has become an important alternative for building applications, especially distributed ones, so it is essential to define new software development processes based on components. Within this trend, we propose a complete framework‐based method which guides application developers in exactly determining application requirements. It also guides how to build them using the compositional framework MultiTEL from the collaborative and multimedia applications domain. Although many multimedia frameworks are available, none of them offer a design methodology for understanding and adapting the framework classes or components to each derived application. By applying an architecture description language (ADL) we are able to document the framework and help designers in: constructing; reusing, and connecting components; extending the framework architecture; and adding components to meet user requirements. Tools for the automatic generation of code from the ADL specifications are also described. Copyright

Building Software Agents from Software Components

The widespread use of the Internet has favored the development of distributed multi-agent systems. The development of agent-based applications is carried out with Agent-Oriented Software Engineering methods, techniques and tools. Although there are several different platforms and methodologies for software agents design, the lack of flexible agent architectures makes the development of multi-agent systems a tiresome and hard task. Current agent architectures provided by these platforms and methodologies do not offer enough flexibility for the development of flexible software agents, placing little emphasis on reuse. This paper presents a software agent development approach using a component-based architecture that promotes building agents from reusable software components. The basis of our approach is the use of component-based software development concepts and the separation of concerns principle to separate agent functionality into independent entities increasing the maintainability and adaptability of the agent to new environments and demands. This architecture simplifies the software agent development process, reducing it to the description of the agents’ software components and interaction protocols using XML documents. The power of Java and Jess technologies has been exploited in the implementation of our compositional model of software agents.

Combining Software Components and Mobile Agents

We present a first approach that combines the mobile agent and the compositional paradigms into a new agent-based compositional model. The aim of this work is to explore the capabilities of both paradigms in improving the design and development of open and distributed systems. Our goal is to add compositional characteristics to mobile agents by defining an agent-based compositional model. We take advantage of the mobility and the composition capability by applying this model to the problem of searching software components in partially-instantiated applications, both in design and run time. That is, the abstract components of an architectural design of an application can be fulfilled with concrete ones by retrieving them from the Internet.

Schedulability Analysis in Real-Time Embedded Systems Specified in SDL

Abstract The use of Formal Description Techniques (FDT) has been proposed as a promising alternative for the development of real-time embedded systems. However, FDT do not incorporate quantitative methods to analyze and predict the timing behaviour of these systems . In this paper, an algorithm to predict the timing behavior of real-time embedded systems designed with SDL is proposed. Also, based on our experiences in the design of these systems, a set of heuristics that redesign the SDL system are incorporated in the algorithm to improve the response times and to meet the deadlines of the events in the system. To illustrate the proposal, an example of a multi-handset cordless telephone is developed.

An Analyzable Execution Model for SDL for Embedded Real-Time Systems

Abstract The usage of formal description techniques has arisen as a promising way to deal with the increasing complexity of the embedded real-time systems. However, these techniques do not take into account relevant non-functional aspects as realtime constraints and hardware interaction. This is the case of the Specification and Description Language (SDL), one of the most used formal techniques. In this paper, different mechanisms to improve SDL real-time expressiveness and prevent real-time anomalies are presented. In addition, a new predictable execution model for SDL and its associated analysis technique are introduced to make possible the real-time analysis of the systems implemented.