The Design of Graphical Process Modeling Languages: from Free Composition to Modular Construction

Un Process Modeling Language (PML) grafico \ue8 un linguaggio specializzato per la modellazione di sistemi software in termini di processi. Tale linguaggio \ue8 detto grafico perch\ue8 la rappresentazione principale dei modelli consiste in diagrammi ottenuti combinando costrutti grafici e componenti precedentemente definiti. Un Process-Aware Information System (PAIS) \ue8 un sistema software guidato da modelli di processi con lo scopo di coordinare e supportare gli agenti nello svolgimento delle loro attivit\ue0. Tale sistema \ue8 responsabile della gestione simulatanea di diverse istanze di processo e del bilanciamento delle risorse disponibili. Un PML \ue8 l'interfaccia principale di un PAIS ed un aspetto fondamentale della sua progettazione, poich\ue8 \ue8 utilizzato da utenti finali, consulenti, e sviluppatori al fine di comprendere, implementare ed eseguire processi complessi. L'utilizzo di tecnologie PAIS pu\uf2 essere considerevolmente limitato dalle carenze di un PML nel descrivere casi complessi. Lo scopo principale della tesi \ue8 migliorare la progettazione di PML grafici al fine di costruire PAIS pi\uf9 efficaci. Tale obiettivo \ue8 perseguito attraverso tre percorsi interconnessi: per prima cosa, i PMLs esistenti e la loro teoria sottostante sono stati analizzati al fine di individuare pregi e difetti; successivamente, una tecnica di verifica molto diffusa in questo campo \ue8 stata consolidata ed estesa con una nuova tecnica per la correzione automatica di processi. Infine, una diversa soluzione per il design di PMLs \ue8 stata esplorata attraverso la definizione di un nuovo linguaggio, chiamato NestFlow, che migliora la modularit\ue0 e la comprensibilit\ue0 attraverso l'adozione di un approccio strutturato alla modellazione di processi. Un approccio modulare \ue8 possible solo se gli aspetti legati ai dati sono accettati come aspetto primario nel design di un PML. NestFlow cerca di semplificare l'attivit\ue0 di modellazione fornendo un insieme integrato di costrutti di control-flow e data-flow, promuovendo i secondi come aspetti principali nella modellazione di processi.A graphical Process Modeling Language (PML) is a language tailored for modeling software systems by means of process models. It is said to be graphical because the primary representation of models are diagrams obtained combining visual constructs and previously defined components. Graphical PMLs are interesting as they open the design space to new geometric representations of complex interrelated aspects like concurrency and interaction. A Process-Aware Information System (PAIS) is a software system driven by explicit process models with the aim to coordinate and support agents in performing their activities. It is responsible for managing several process model instances at the same time balancing the available resources. A PML is the primary interface of a PAIS and a main concern in its design, because it is used by end-users, consultants, and developers for understanding, implementing and enacting complex processes. The adoption of PAIS technology may be severely limited by the weakness of PMLs in describing complex use cases. The overall aim of this thesis is to improve the design of graphical PMLs in order to engineer more effective PAISs. This goal is pursued following three intertwined paths: firstly, mainstream PMLs and their theoretical foundations are analyzed for exposing their features and limits; secondly, a widespread PML verification method is consolidated and then extended with a novel technique for automating process correction; finally, an alternative PML design solution is explored through a proof-of-concept language, called NestFlow, that improves both modularity and comprehensibility by providing a more structured modeling approach. A modular approach is only possible if data-flow dependencies are accepted as a main concern in PML design. NestFlow tries to ease the modeling activity by providing a comprehensive set of tightly integrated control-flow and data-flow constructs, promoting the latter as first-class citizens in process modeling

Eighth Workshop and Tutorial on Practical Use of Coloured Petri Nets and the CPN Tools, Aarhus, Denmark, October 22-24, 2007

This booklet contains the proceedings of the Eighth Workshop on Practical Use of Coloured Petri Nets and the CPN Tools, October 22-24, 2007. The workshop is organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark. The papers are also available in electronic form via the web pages: http://www.daimi.au.dk/CPnets/workshop0

GinFlow: A Decentralised Adaptive Workflow Execution Manager

International audienceWorkflow-based computing has become a dominant paradigm to design and execute scientific applications. After the initial breakthrough of now standard workflow management systems, several approaches have recently proposed to decentralise the coordination of the execution. In particular, shared space-based coordination has been shown to provide appropriate building blocks for such a decentralised execution. Uncertainty is also still a major concern in scientific workflows. The ability to adapt the workflow, change its shape and switch for alternate scenarios on-the-fly is still missing in workflow management systems. In this paper, based on the shared space model, we firstly devise a programmatic way to specify such adaptive workflows. We use a reactive, rule-based programming model to modify the workflow description by changing its associated directacyclic graph on-the-fly without needing to stop and restart the execution from the beginning. Secondly, we present the GinFlow middleware, a resilient decentralised workflow execution manager implementing these concepts. Through a set of deployments of adaptive workflows of different characteristics, we discuss the GinFlow performance and resilience and show the limited overhead of the adaptiveness mechanism, making it a promising decentralised adaptive workflow execution manager

Mathematics in Software Reliability and Quality Assurance

This monograph concerns the mathematical aspects of software reliability and quality assurance and consists of 11 technical papers in this emerging area. Included are the latest research results related to formal methods and design, automatic software testing, software verification and validation, coalgebra theory, automata theory, hybrid system and software reliability modeling and assessment

Linguistic Refactoring of Business Process Models

In the past decades, organizations had to face numerous challenges due to intensifying globalization and internationalization, shorter innovation cycles and growing IT support for business. Business process management is seen as a comprehensive approach to align business strategy, organization, controlling, and business activities to react flexibly to market changes. For this purpose, business process models are increasingly utilized to document and redesign relevant parts of the organization's business operations. Since companies tend to have a growing number of business process models stored in a process model repository, analysis techniques are required that assess the quality of these process models in an automatic fashion. While available techniques can easily check the formal content of a process model, there are only a few techniques available that analyze the natural language content of a process model. Therefore, techniques are required that address linguistic issues caused by the actual use of natural language. In order to close this gap, this doctoral thesis explicitly targets inconsistencies caused by natural language and investigates the potential of automatically detecting and resolving them under a linguistic perspective. In particular, this doctoral thesis provides the following contributions. First, it defines a classification framework that structures existing work on process model analysis and refactoring. Second, it introduces the notion of atomicity, which implements a strict consistency condition between the formal content and the textual content of a process model. Based on an explorative investigation, we reveal several reoccurring violation patterns are not compliant with the notion of atomicity. Third, this thesis proposes an automatic refactoring technique that formalizes the identified patterns to transform a non-atomic process models into an atomic one. Fourth, this thesis defines an automatic technique for detecting and refactoring synonyms and homonyms in process models, which is eventually useful to unify the terminology used in an organization. Fifth and finally, this thesis proposes a recommendation-based refactoring approach that addresses process models suffering from incompleteness and leading to several possible interpretations. The efficiency and usefulness of the proposed techniques is further evaluated by real-world process model repositories from various industries. (author's abstract

Web service composition: A survey of techniques and tools

Web services are a consolidated reality of the modern Web with tremendous, increasing impact on everyday computing tasks. They turned the Web into the largest, most accepted, and most vivid distributed computing platform ever. Yet, the use and integration of Web services into composite services or applications, which is a highly sensible and conceptually non-trivial task, is still not unleashing its full magnitude of power. A consolidated analysis framework that advances the fundamental understanding of Web service composition building blocks in terms of concepts, models, languages, productivity support techniques, and tools is required. This framework is necessary to enable effective exploration, understanding, assessing, comparing, and selecting service composition models, languages, techniques, platforms, and tools. This article establishes such a framework and reviews the state of the art in service composition from an unprecedented, holistic perspective