Antonio Bucchiarone

Web Service Composition Approaches: From Industrial Standards to Formal Methods

Composition of Web services is much studied to support business-to-business and enterprise application integration in e-commerce. Current Web service composition approaches range from practical languages aspiring to become standards (like BPEL, WS-CDL, OWL-S and WSMO) to theoretical models (like automata, Petri nets and process algebras). In this paper we compare these approaches w.r.t. a selected set of characteristics (like trust, security and performance) and we advocate the use of formal models, and their tool support, to increase ones confidence in web service compositions. This paper can assist web service composition designers and developers to deliver lasting solutions, in concordance with the technologys critical needs.

Dynamic Adaptation of Fragment-Based and Context-Aware Business Processes

We propose a comprehensive framework for adaptivity of service-based applications, which exploits the concept of process fragments as a way to model reusable process knowledge and to allow for the dynamic, incremental, context-aware composition of such fragments into adaptable service-based applications. The framework provides a set of adaptation mechanisms that, combined through adaptation strategies, are able to solve complex adaptation problems. An implementation of the proposed solution is presented and evaluated on a real world scenario from the logistics domain.

Design for adaptation of service-based applications: main issues and requirements

Service-based applications are considered a promising technology since they are able to offer complex and flexible functionalities in widely distributed environments by composing different types of services. These applications have to be adaptable to unforeseen changes in the functionality offered by component services and to their unavailability or decreasing performances. Furthermore, when applications are made available to a high number of potential users, they should also be able to dynamically adapt to the current context of use as well as to specific requirements and needs of the specific users. In order to address these issues, mechanisms that enable adaptation should be introduced in the life-cycle of applications, both in the design and in the runtime phases. In this paper we propose an extension of a basic iterative service-based applications lifecycle with elements able to deal with the adaptation-specific needs. We focus, in particular, on the design phase and suggest a number of design principles and guidelines that are suitable to enable adaptation. We discuss about the effectiveness of the proposed methodology by means of real-world scenarios over various types of service-based applications.

Modelling Dynamic Software Architectures using Typed Graph Grammars

Several recent research efforts have focused on the dynamic aspects of software architectures providing suitable models and techniques for handling the run-time modification of the structure of a system. A large number of heterogeneous proposals for addressing dynamic architectures at many different levels of abstraction have been provided, such as programmable, ad-hoc, self-healing and self-repairing among others. It is then important to have a clear picture of the relations among these proposals by formulating them into a uniform framework and contrasting the different verification aspects that can be reasonably addressed by each proposal. Our work is a contribution in this line. In particular, we map several notions of dynamicity into the same formal framework in order to distill the similarities and differences among them. As a result we explain different styles of architectural dynamisms in term of graph grammars and get some better insights on the kinds of formal properties that can be naturally associated to such different specification styles. We take a simple automotive scenario as a running example to illustrate main ideas.

A framework for rule-based dynamic adaptation

We propose a new approach to dynamic adaptation, based on the combination of adaptation hooks provided by the adaptable application specifying where adaptation can happen, and adaptation rules external to the application, specifying when and how adaptation can be performed. We discuss different design choices that have to be considered when using such an approach, and then we propose a possible solution. We describe the solution in details, we apply it to a sample scenario and we implement it on top of the language Jolie.

TESTOR: deriving test sequences from model-based specifications

The dependability analysis of a component-based system may be driven by the components/system implementation or by the model-based specification provided prior to or together with the implementation. In particular, model-based specifications of a component-based system allows to explicitly model the structure and behavior of components and their integration, while model-based testing allows to derive test sequences which can be successively refined into test cases and then run onto the system implementation. Several techniques have been proposed so far to allow model-based testing. However, very few of them show certain characteristics which are peculiar for use in industrial contexts. We here describe TeStor, a TEst Sequence generaTOR algorithm which allows to extract test sequences from both state machine and scenario diagrams. We detail the algorithm, we apply it to a system study and we provide a link to its implementation.

Formal analysis and verification of self-healing systems

Self-healing (SH-)systems are characterized by an automatic discovery of system failures, and techniques how to recover from these situations. In this paper, we show how to model SH-systems using algebraic graph transformation. These systems are modeled as typed graph grammars enriched with graph constraints. This allows not only for formal modeling of consistency and operational properties, but also for their analysis and verification using the tool AGG. We present sufficient static conditions for self-healing properties, deadlock-freeness and liveness of SH-systems. The overall approach is applied to a traffic light system case study, where the corresponding properties are verified.

Graph-Based Design and Analysis of Dynamic Software Architectures

We illustrate two ways to address the specification, modelling and analysis of dynamic software architectures using: i) ordinary typed graph transformation techniques implemented in Alloy; ii) a process algebraic presentation of graph transformation implemented in Maude. The two approaches are compared by showing how different aspects can be tackled, including representation issues, modelling phases, property specification and analysis.

Adaptation of service-based business processes by context-aware replanning

Service-based business processes are typically used by organizations to achieve business goals through the coordinated execution of a set of activities implemented as services and service compositions. Since they are executed in dynamic, open and non-deterministic environments, business processes often need to be adapted to exogenous context changes and execution problems. In this paper we provide an adaptation approach that can automatically adapt business processes to run-time context changes that impede achievement of a business goal. We define a formal framework that adopts planning techniques to automatically derive necessary adaptation activities on demand. The adaptation consists in identifying recovery activities that guarantee that the execution of a business process can be successfully resumed and, as a consequence, the business goals are achieved. The solution proposed is evaluated on a real-world scenario from the logistics domain.

Quality analysis of NL requirements: an industrial case study

Nowadays common practice indicates that the requirement engineering (RE) process critically influences the success of the system development life cycle. Several commercial tools allow to classify, archive and manage requirements and then to print out reports and requirement documents. QuARS (Quality Analyzer for Requirements Specifications) is an automatic analyzer of such requirement documents, developed by ISTI-CNR, that can be adopted to evaluate the document quality by linguistic point of view. This paper presents how a requirement management tool, an automatic document generator, and QuARS can be integrated to define an RE automation support. The case study investigates and highlights the efficacy and the role of such proposed support in the Siemens C.N.X. development process.