Luca Sabatucci

Patterns reuse in the PASSI methodology

Design patterns already proved successful in lowering the development time and number of errors of object-oriented software; now, they are, candidate to play a similar role in the MAS (multi-agent system) context. In this work we describe our experiences in the identification, production and application of patterns for agents. Some patterns are described together with the classification criteria and documentation approach we adopt. Upon them, we base a pattern reuse process that can be considered one of the distinguishing elements of the design methodology (PASSI) we use to develop MAS. Patterns can be applied to an existing agent or used to produce a new one with the support of a specific web based application that can read both the JAVA source code and XMI representation of the agent design documentation. After the successful application of the desired pattern(s), the source code and the design diagrams (usually a structural and dynamic diagram) of the agent can be exported. Some experimental results are reported in order to demonstrate the utility of this approach in automatically producing an interesting percentage of code lines.

A possible approach to the development of robotic multi-agent systems

The design of an agent system for robotics is a problem that involves aspects coming from many different disciplines (robotics, artificial intelligence, computer vision, software engineering). The most difficult part of it, often consists in producing and tuning the algorithms that incorporates the robot behavior (planning, obstacle avoidance,...) and abilities (vision, manipulation, navigation,...). Frequently, the reuse of these parts is left to a copy and paste procedure from previous applications to the new one. In so doing many problems could arise. We propose a comprehensive approach for multi-agent systems oriented to robotics applications that uses a complete design methodology supported by a specific design tools and a pattern repository that interacting each other and with the designer allow the production of a coherent design that easily incorporates patterns coming from previously experienced features and automatically produces a large part of the final code.

The PASSI and agile PASSI MAS meta-models compared with a unifying proposal

A great number of processes for multi-agent systems design have been presented in last years to support the different approaches to agent-oriented design; each process is specific for a particular class of problems and it instantiates a specific MAS meta-model. These differences produce inconsistences and overlaps: a MAS meta-model may define a term not referred by another, or the same term can be used with a different meaning. We think that the lack of a standardization may cause a significant delay to the diffusion of the agent paradigm outside research context. Working for this unification goal, it is also necessary to define in unambiguous way the terms of the agent model and their relationships thus obtaining a unified MAS meta-model. In this work we propose the PASSI MAS meta-model, the results of its adaptation to the needs of an agile process (Agile PASSI), and a comparison with an existing unifying proposal of MAS meta-model composed by considering three different processes (ADELFE, Gaia and PASSI).

From PASSI to Agile PASSI: tailoring a design process to meet new needs

From several years we are developing robotic multi-agent systems according to well defined design methodologies. These methodologies evolved over time because of the changes in the operating environments (robotic hardware and software platforms) and specific missions accomplished by our robots. In the last four years we used PASSI (Process for Agent Societies Specification and Implementation) obtaining good results but, the growing experience and day by day accelerating changes in requirements suggested us to find a new and more versatile approach. In this context we developed the Agile PASSI methodology discussed in This work; it is an agile process built up capitalizing all the experiences done with PASSI and its supporting tools some of which have been adapted and reused in the new process.

Agent-oriented software patterns for rapid and affordable robot programming

Robotic systems are often quite complex to develop; they are huge, heavily constrained from the non-functional point of view and they implement challenging algorithms. The lack of integrated methods with reuse approaches leads robotic developers to reinvent the wheel each time a new project starts. This paper proposes to reuse the experience done when building robotic applications, by catching it into design patterns. These represent a general mean for (i) reusing proved solutions increasing the final quality, (ii) communicating the knowledge about a domain and (iii) reducing the development time and effort. Despite of this generality, the proposed repository of patterns is specific for multi-agent robotic systems. These patterns are documented by a set of design diagrams and the corresponding implementing code is obtained through a series of automatic transformations. Some patterns extracted from an existing and freely available repository are presented. The paper also discusses an experimental set-up based on the construction of a complete robotic application obtained by composing some highly reusable patterns.

From means-end analysis to proactive means-end reasoning

Self-adaptation is a prominent property for developing complex distributed software systems. Notable approaches to deal with self-adaptation are the runtime goal model artifacts. Goals are generally invariant along the system lifecycle but contain points of variability for allowing the system to decide among many alternative behaviors. This work investigates how it is possible to provide goal models at run-time that do not contain tasks, i.e. The description of how to address goals, thus breaking the design-time tie up between Tasks and Goals, generally outcome of a means-end analysis. In this vision the system is up to decide how to combine its available Capabilities: the Proactive Means-End Reasoning. The impact of this research line is to implement a goal-oriented form of self-adaptation where goal models can be injected at runtime. The paper also introduces MUSA, a Middleware for User-driven Service self-Adaptation.

Highly Customizable Service Composition and Orchestration

One of the current challenges of Service Oriented Engineering is to provide instruments for dealing with dynamic and unpredictable user requirements and environment. Traditional approaches based on workflow for orchestrating services provide little support for configuring at run-time the flow of activities.

A collaborative tool for designing and enacting design processes

Today several approaches using Situational Method Engineering paradigm exist, each of them proposes methods and techniques for developing ad-hoc design processes. In this context heavy efforts were spent in the construction of appropriate tools that could help method engineers in producing a specific design process and in using it. We developed a tool called Metameth for supporting the design process definition and its enactment. Metameth is implemented as a multi-agent system, where each agent is capable of reasoning and adapting itself in order to support the designer in performing different kinds of design activities.

Conquering Fine-Grained Blends of Design Patterns

The reuse of design patterns in realistic software systems is often a result of blending multiple pattern elements together rather than instantiating them in an isolated manner. The explicit description of pattern compositions is the key for (i) documenting the structure and the behavior of blended patterns and, (ii) more importantly, supporting the reuse of composite patterns across different software projects. In this context, this paper proposes a fine-grained composition language for describing varying blends of design patterns based on their structural and behavioural semantics. The reusability and expressiveness of the proposed language are assessed through its application to 32 compositions of GoF patterns recurrently appearing in three different case studies: the OpenOrb middleware, the JHotDraw and JUnit frameworks.

Generating and Instantiating Abstract Workflows with QoS User Requirements.

The growing availability of services accessible through the network makes it possible to build complex applications resulting from their composition that are usually characterized also by non-functional properties, known as Quality of Service (QoS). To exploit the full potential of service technology, automatic QoS-based composition of services is crucial. In this work a framework for automatic service composition is presented that relies on planning and service negotiation techniques for addressing both functional and non-functional requirements. The proposed approach allows for dynamic service composition and QoS attributes, and it can be applied when services are provided in the contest of a competitive market of service providers without knowledge disclosure.