SPIN is an efficient verification system for models of distributed software systems. It has been used to detect design errors in applications ranging from high-level descriptions of distributed algorithms to detailed code for controlling telephone exchanges. The paper gives an overview of the design and structure of the verifier, reviews its theoretical foundation, and gives an overview of significant practical applications.

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The model checker SPIN

Explanation in artificial intelligence: Insights from the social sciences

http://emamispnu.persiangig.com/Projects/Cloud%20Computing/science_2.pdf

Review: A survey on security issues in service delivery models of cloud computing

Our goal in this paper is to introduce and motivate a methodology, called Tropos,1 for building agent oriented software systems. Tropos is based on two key ideas. First, the notion of agent and all related mentalistic notions (for instance goals and plans) are used in all phases of software development, from early analysis down to the actual implementation. Second, Tropos covers also the very early phases of requirements analysis, thus allowing for a deeper understanding of the environment where the software must operate, and of the kind of interactions that should occur between software and human agents. The methodology is illustrated with the help of a case study. The Tropos language for conceptual modeling is formalized in a metamodel described with a set of UML class diagrams.

/pdf/tropos-an-agent-oriented-software-development-methodology-4cfpp4zfvj.pdf

Tropos: An Agent-Oriented Software Development Methodology

Over the Internet today, computing and communications environments are significantly more complex and chaotic than classical distributed systems, lacking any centralized organization or hierarchical control. There has been much interest in emerging Peer-to-Peer (P2P) network overlays because they provide a good substrate for creating large-scale data sharing, content distribution, and application-level multicast applications. These P2P overlay networks attempt to provide a long list of features, such as: selection of nearby peers, redundant storage, efficient search/location of data items, data permanence or guarantees, hierarchical naming, trust and authentication, and anonymity. P2P networks potentially offer an efficient routing architecture that is self-organizing, massively scalable, and robust in the wide-area, combining fault tolerance, load balancing, and explicit notion of locality. In this article we present a survey and comparison of various Structured and Unstructured P2P overlay networks. We categorize the various schemes into these two groups in the design spectrum, and discuss the application-level network performance of each group.

/pdf/a-survey-and-comparison-of-peer-to-peer-overlay-network-cpcv2ij1hk.pdf

A survey and comparison of peer-to-peer overlay network schemes

The ability to automatically compose web services, and to monitor their execution, is an essential step to substantially decrease time and costs in the development, integration, and maintenance of complex services. In this paper, we exploit techniques based on the “Planning as Model Checking” approach to automatically compose web services and synthesize monitoring components. By relying on such a flexible technology, we are able to deal with the difficulties stemming from the unpredictability of external partner services, the opaqueness of their internal status, and the presence of complex behavioral requirements. We test our approach on a simple, yet realistic example; the results provide a witness to the potentiality of this approach.

Planning and Monitoring Web Service Composition

In this paper, we address the problem of the automated composition of web services by planning on their "knowledge level" models. We start from descriptions of web services in standard process modeling and execution languages, like BPEL4WS, and automatically translate them into a planning domain that models the interactions among services at the knowledge level. This allows us to avoid the explosion of the search space due to the usually large and possibly infinite ranges of data values that are exchanged among services, and thus to scale up the applicability of state-of-the-art techniques for the automated composition of web services. We present the theoretical framework, implement it, and provide an experimental evaluation that shows the practical advantage of our approach w.r.t. techniques that are not based on a knowledgelevel representation.

/pdf/automated-composition-of-web-services-by-planning-at-the-37je7cbmtu.pdf

Automated composition of web services by planning at the knowledge level

The goal of this paper is to provide an introduction, with various elements of novelty, to the Planning as Model Checking paradigm.

Planning as Model Checking

Summary Service-Oriented Computing (SOC) is a new computing paradigm that utilizes services as the basic constructs to support the development of rapid, low-cost and easy composition of distributed applications even in heterogeneous environments. The visionary promise of Service-Oriented Computing is a world of cooperating services where application components are assembled with little effort into a network of services that can be loosely coupled to create flexible dynamic business processes and agile applications that may span organisations and computing platforms. SOC is being shaped by, and increasingly will help shape, modern society as a whole, especially in the areas of dynamic and ondemand business and education, health and government services. The subject of SOC is vast and enormously complex, spanning many concepts and technologies that find their origins in diverse disciplines that are woven together in an intricate manner. In addition, there is a need to merge technology with an understanding of business processes and organizational structures, a combination of recognizing an enterprise's pain points and the potential solutions that can be applied to correct them. The material in research spans an immense and diverse spectrum of literature, in origin and in character. As a result research activities at both worldwide as well as at European level are very fragmented. This necessitates that a broader vision and perspective be established—one that permeates and transforms the fundamental requirements of complex applications that require the use of the SOC paradigm. This will further enhance the value proposition of ServiceOriented Computing and will facilitate the formulation of a Services Research Roadmap leading to more effective and clearly inter-related solutions and better exploitation of research results. This document provides the necessary background for deciding on potential future research programmes in SOC and places on-going research activities and projects in the broader context of a SOC Roadmap. This research roadmap launches four pivotal, inherently related, research themes to SOC: service foundations, service composition, service management and monitoring and service-oriented engineering. The viewpoints presented in this document partly result from intensive discussions experts with various backgrounds led in parallel workgroup and in plenary sessions that took place during the International Dagstuhl Seminar on Service-Oriented Computing held November 15-18, 2005, in Schloss Dagstuhl, Wadern. Each theme is introduced briefly from a technology, state of the art and scientific challenges standpoint. From the technology standpoint a comprehensive review of state of the art, standards, and current research activities in each key area is provided. From the state of the art the major open problems and bottlenecks to progress are identified. Several of these obstacles arise due to the current lack of interdisciplinary research in the field, which is considered to be a major impediment that limits added economic growth through deployment and use of services technology. Finally, the scientific challenges that tackle the found obstacles are formulated. These are long-term visions that serve as integration platforms and demonstrators for an holistic approach to Service Oriented Computing in the identified key areas. These future research activities form a sound background for deciding on potential future programmes in SOC.

/pdf/service-oriented-computing-research-roadmap-3wqm8m4lcc.pdf

Service-Oriented Computing Research Roadmap

We describe an attempt to bridge the gap between early requirements specification and formal methods. In particular, we propose a new specification language, called Formal Tropos, that is founded on the primitive concepts of early requirements frameworks (actor, goal, strategic dependency) (Yu, 1997), but supplements them with a rich temporal specification language. We also extend existing formal analysis techniques, in particular model checking, to allow for an automatic verification of relevant properties for an early requirements specification. Our preliminary experiments demonstrate that formal analysis reveals gaps and inconsistencies in early requirements that are by no means trivial to discover without the help of formal analysis tools.

/pdf/model-checking-early-requirements-specifications-in-tropos-3auhcy73bw.pdf

Paolo Traverso

Papers

Planning and Monitoring Web Service Composition

Automated composition of web services by planning at the knowledge level

Planning as Model Checking

Service-Oriented Computing Research Roadmap

Model checking early requirements specifications in Tropos