Fabio Patrizi

Verification of deployed artifact systems via data abstraction

Artifact systems are a novel paradigm for specifying and implementing business processes described in terms of interacting modules called artifacts. Artifacts consist of data and lifecycle models, accounting for the relational structure of the artifact state and its possible evolutions over time. We consider the problem of verifying artifact systems against specifications expressed in quantified temporal logic. This problem is in general undecidable. However, when artifact systems are deployed, their states can contain only a bounded number of elements. We exploit this fact to develop an abstraction technique that enables us to verify deployed artifact systems by model checking their bounded abstraction.

Automated service composition based on behaviors: The roman model

During the last years, many approaches have been proposed in order to address the issue of automated service composition. In this chapter, we discuss the so-called “Roman model”, in which services are abstracted as transition systems and the objective is to obtain a composite service that preserves a desired interaction, expressed as a (virtual) target service. We will also outline its deployment in the challenging applications of smart houses, i.e., buildings pervasively equipped with sensors and actuators making their functionalities available according to the service-oriented paradigm.

A computationally-grounded semantics for artifact-centric systems and abstraction results

We present a formal investigation of artifact-based systems, a relatively novel framework in service oriented computing, aimed at laying the foundations for verifying these systems through model checking. We present an infinite-state, computationally grounded semantics for these systems that allows us to reason about temporal-epistemic specifications. We present abstraction techniques for the semantics that guarantee transfer of satisfaction from the abstract system to the concrete one.

Computing infinite plans for LTL goals using a classical planner

Classical planning has been notably successful in synthesizing finite plans to achieve states where propositional goals hold. In the last few years, classical planning has also been extended to incorporate temporally extended goals, expressed in temporal logics such as LTL, to impose restrictions on the state sequences generated by finite plans. In this work, we take the next step and consider the computation of infinite plans for achieving arbitrary LTL goals. We show that infinite plans can also be obtained efficiently by calling a classical planner once over a classical planning encoding that represents and extends the composition of the planning domain and the Buchi automaton representing the goal. This compilation scheme has been implemented and a number of experiments are reported.

AutomaticWorkflows Composition of Mobile Services

Pervasive computing environments are nowadays more and more used as a supporting tool for cooperative workflows, e.g., in emergency management. A typical problem in these scenarios is the synthesis of workflows in presence of sets of services (hosted on mobile devices) with constrained behaviors, just before the collaborating team is dropped off in the operation field. In this paper, we propose a technique able to automatically synthesize distributed orchestrators, each one coordinating a service and synchronizing with the other orchestrators, given a target generic workflow to be carried out and a set of behaviorally-constrained services.

Service-Oriented Computing – ICSOC 2013 Workshops

Business process management has become a standard commodity to manage and improve business operations in organisations. Large process model collections emerged. Managing, and maintaining them has become a major area of research. Business process architectures (BPAs) have been introduced to support this task focusing on interdependencies between processes. Both the process and BPA layer are often modeled independently, creating inconsistencies between both layers. However, a consistent overview on process interdependencies on BPA level is of high importance, especially in regard to assessing the impact of change when optimising business process collaborations. In this paper, we propose a formal approach to extract BPAs from process model collections connecting process layer and BPA layer for assuring consistency between them. Interdependencies between process models will be reflected in trigger and message flows on BPA level giving a high level overview of process collaboration as well as allowing its formal verification with existing approaches. We will show the extraction of BPAs from process model collections on a running example modeled in BPMN.

Agent planning programs

This work proposes a novel high-level paradigm, agent planning programs, for modeling agents behavior, which suitably mixes automated planning with agent-oriented programming. Agent planning programs are finite-state programs, possibly containing loops, whose atomic instructions consist of a guard, a maintenance goal, and an achievement goal, which act as precondition-invariance-postcondition assertions in program specification. Such programs are to be executed in possibly nondeterministic planning domains and their execution requires generating plans that meet the goals specified in the atomic instructions, while respecting the program control flow. In this paper, we define the problem of automatically synthesizing the required plans to execute an agent planning program, propose a solution technique based on model checking of two-player game structures, and use it to characterize the worst-case computational complexity of the problem as EXPTIME-complete. Then, we consider the case of deterministic domains and propose a different technique to solve agent planning programs, which is based on iteratively solving classical planning problems and on exploiting goal preferences and plan adaptation methods. Finally, we study the effectiveness of this approach for deterministic domains through an experimental analysis on well-known planning domains.

Bounded situation calculus action theories

In this paper,1 we investigate bounded action theories in the situation calculus. A bounded action theory is one which entails that, in every situation, the number of object tuples in the extension of fluents is bounded by a given constant, although such extensions are in general different across the infinitely many situations. We argue that such theories are common in applications, either because facts do not persist indefinitely or because the agent eventually forgets some facts, as new ones are learned. We discuss various classes of bounded action theories. Then we show that verification of a powerful first-order variant of the µ-calculus is decidable for such theories. Notably, this variant supports a controlled form of quantification across situations. We also show that through verification, we can actually check whether an arbitrary action theory maintains boundedness.

First-order μ-calculus over generic transition systems and applications to the situation calculus

Abstract We consider μ L , μ L a , and μ L p , three variants of the first-order μ-calculus studied in verification of data-aware processes, that differ in the form of quantification on objects across states. Each of these three logics has a distinct notion of bisimulation. We show that the three notions collapse for generic dynamic systems, which include all state-based systems specified using a logical formalism, e.g., the situation calculus. Hence, for such systems, μ L , μ L a , and μ L p have the same expressive power. We also show that, when the dynamic system stores only a bounded number of objects in each state (e.g., for bounded situation calculus action theories), a finite abstraction can be constructed that is faithful for μ L (the most general variant), yielding decidability of verification. This contrasts with the undecidability for first-order ltl , and notably implies that first-order ltl cannot be captured by μ L .

Guest editorial: special issue on data and artifact-centric business processes

Traditionally, researchers in the field of Business Process Management (BPM) have focused on studying control-flow aspects of business processes independently from data aspects. The separation of concerns between control-flow and data has been fruitful and has enabled the development of various foundational theories and methods for BPM. However, the limits of theories and methods built on this separation of concerns have now become evident, particularly with the increasing pressure to support ad hoc and flexible business processes, where control-flow is often intermingled with data. In the past decade, various approaches have emerged that emphasize the integration of data and control as key pillars to support the specification, analysis, enactment, and monitoring of rich and flexible business processes. These include object-centric and artifact-centric approaches, where data and behavior are bundled together into logical units, as well as case management approaches, where a process is viewed as cases where data and documents circulate across multiple actors in a way that is not necessarily driven by normative procedures. This special issue focuses on the former family approaches, where research has attained a certain level of maturity in recent years. The issue showcases four research contributions pertaining to dataand artifactcentric approaches to BPM.