Loupe: Verifying Publish-Subscribe Architectures with a Magnifying Lens

CONE

Petri Nets as Semantic Domain for Diagram Notations

AbstractThis paper summarizes the work carried out by the authors during the last years. It proposes an approach for defining extensible and flexible formal interpreters for diagram notations based on high-level timed Petri nets.The approach defines interpreters by means of two sets of rules. The first set specifies the correspondences between the elements of the diagram notation and those of the semantic domain (Petri nets); the second set transforms events and states of the semantic domain into visual annotations on the elements of the diagram notation. The feasibility of the approach is demonstrated through MetaEnv, a prototype tool that allows users to implement special-purpose interpreters

Self-supervising BPEL Processes

Service compositions suffer changes in their partner services. Even if the composition does not change, its behavior may evolve over time and become incorrect. Such changes cannot be fully foreseen through prerelease validation, but impose a shift in the quality assessment activities. Provided functionality and quality of service must be continuously probed while the application executes, and the application itself must be able to take corrective actions to preserve its dependability and robustness. We propose the idea of self-supervising BPEL processes, that is, special-purpose compositions that assess their behavior and react through user-defined rules. Supervision consists of monitoring and recovery. The former checks the system's execution to see whether everything is proceeding as planned, while the latter attempts to fix any anomalies. The paper introduces two languages for defining monitoring and recovery and explains how to use them to enrich BPEL processes with self-supervision capabilities. Supervision is treated as a cross-cutting concern that is only blended at runtime, allowing different stakeholders to adopt different strategies with no impact on the actual business logic. The paper also presents a supervision-aware runtime framework for executing the enriched processes, and briefly discusses the results of in-lab experiments and of a first evaluation with industrial partners

Towards a Formal Semantics for UML/MARTE State Machines Based on Hierarchical Timed Automata

n/

Towards Distributed BPEL Orchestrations

Web services are imposing as the technology to integrate highly heterogeneous systems. BPEL, the standard technology to compose services, assumes a single âorchestratorâ that controls the execution flow and coordinates the interactions with selected services. This centralized approach simplifies the coordination among components, but it is also a too heavy constraint. To this end, the paper introduces the idea of distributed orchestrations and presents a proposal to couple BPEL and distributed execution in mobile settings. The approach âexemplified on a simple case studyâ transforms a centralized BPEL process into a set of coordinated processes. An explicit meta-model and graph transformation supply the formal grounding to obtain a set of related processes, and to add the communication infrastructure among the newly created processes. The paper also presents a communication infrastructure based on tuple spaces to make the different orchestrators interact in mobile contexts. Keywords: WS-BPEL, Grap

On Handling Business Process Anomalies through Artifact-based Modeling

Control flow-based process modeling notations, like BPMN, are good at dening the normal execution flow and the management of foreseen exceptions. When unforeseen situations occur, one cannot detect if the execution is still acceptable with respect to the process definition. In contrast, artifact-centric process modeling notations, like the Guard-Stage-Milestone (GSM), are better suited for this kind of scenarios: they define a process in terms of acceptable states and do not enforce any specific execution flow. This improves flexibility, but hampers the clarity of the defined models. The goal of this paper is to show how an extension of GSM, i.e., E-GSM, can be used to detect deviations from the execution path as modeled in BPMN, while keeping the process execution alive

PLCTOOLS: Graph Transformation Meets PLC Design

Abstract This paper presents PLCTOOLS, a formal environment for designing and simulating programmable controllers. Control models are specified with IEC FED (Function Block Diagram), and translated into functionally equivalent HLTPNs (High-Level Timed Petri Nets), through MetaEnv, for analysis and simulation and obtained results are presented in terms of suitable animations of FED blocks. The peculiarity with FBD is that it does not come with a fixed set of syntactic elements; it allows users to add as many new blocks as they want. Consequently, each time users want to add a new FBD block with PLCTOOLS, they must provide the concrete syntax, to add it to the library of available blocks, but also the associated HLTPN, to allow MetaEnv to build the formal representation

Service-Oriented Dynamic Software Product Lines

An operational example of controls in a smart home demonstrates the potential of a solution that combines the Common Variability Language and a dynamic extension of the Business Process Execution Language to address the need to manage software system variability at runtime