Workflow simulation for operational decision support using YAWL and ProM

Simulation is widely used as a tool for analyzing business processes but is mostly focused on examining rather abstract steady-state situations. Such analyses are helpful for the initial design of a business process but are less suitable for operational decision making and continuous improvement. Here we describe a simulation system for operational decision support in the context of work ow management. To do this we exploit not only the work ow's design, but also logged data describing the system's observed historic behavior, and information extracted about the current state of the work ow. Making use of actual data capturing the current state and historic information allows our simulations to accurately predict potential near-future behaviors for dierent scenarios. The approach is supported by a practical toolset which combines and extends the work ow management system YAWL and the process mining framework ProM. This technical report contains a detailed description of how a simulation model including operational decision support can be generated by our software based on the running example

Integrating discrete- and continuous-time metric temporal logics through sampling

Abstract. Real-time systems usually encompass parts that are best described by a continuous-time model, such as physical processes under control, together with other components that are more naturally formalized by a discrete-time model, such as digital computing modules. Describing such systems in a unified framework based on metric temporal logic requires to integrate formulas which are interpreted over discrete and continuous time. In this paper, we tackle this problem with reference to the metric temporal logic TRIO, that admits both a discrete-time and a continuous-time semantics. We identify sufficient conditions under which TRIO formulas have a consistent truth value when moving from continuous-time to discrete-time interpretations, or vice versa. These conditions basically involve the restriction to a proper subset of the TRIO language and a requirement on the finite variability over time of the basic items in the specification formulas. We demonstrate the approach with an example of specification and verification

Formal definition of priority in CSP

The process models of Ada and occam are formally based on the CSP process algebra. However, for fine-tuning real-time performance, they include “prioritized” constructs that have no counterparts in CSP. These constructs therefore lack any formal definition, a situation that leaves room for misunderstandings. We extend CSP with a formal definition of the notion of priority. The definition is then used to assess the transputer implementation of priority in occam and the definition of priority in Ada

Refinement rules for real-time multi-tasking programs

We present several formal program refinement rules for designing multi-tasking programs with hard real-time constraints

Modelling Program Compilation in the Refinement Calculus

We show how compilation of high-level language programs to assembler code can be formally represented in the refinement calculus. New operators are introduced to widen the modelling language to encompass assembler code. A compilation strategy is then embodied as a set of derived refinement rules. 1 Introduction The idea of modelling program compilation as a formal development procedure has surfaced many times in the literature, but has presented a significant challenge. This has resulted in complex models, often using new, unfamiliar formalisms. Our goal is to develop a model of program compilation within the alreadyfamiliar refinement calculus. Normally the refinement calculus translates an abstract requirements specification into a programming language implementation, using guarded command language augmented with specification statements as the underlying modelling notation. In the context of compilation, however, our `specification' is a high-level language (HLL) program, an..

Detecting Errors in Multithreaded Programs by Generalized Predictive Analysis of Executions

A generalized predictive analysis technique is proposed for detecting violations of safety properties from apparently successful executions of multithreaded programs. Specifically, we provide an algorithm to monitor executions and, based on observed causality, predict other schedules that are compatible with the run. The technique uses a weak happens-before relation which orders a write of a shared variable with all its subsequent reads that occur before the next write to the variable. A permutation of the observed events is a possible execution of a program if and only if it does not contradict the weak happens-before relation. Even though an observed execution trace may not violate the given specification, our algorithm infers other possible executions (consistent with the observed execution) that violate the given specification, if such an execution exists

Business process simulation for operational decision support

Contemporary business process simulation environments are geared towards design-time analysis, rather than operational decision support over already deployed and running processes. In particular, simulation experiments in existing process simulation environments start from an empty execution state. We investigate the requirements for a process simulation environment that allows simulation experiments to start from an intermediate execution state. We propose an architecture addressing these requirements and demonstrate it through a case study conducted using the YAWL workflow engine and CPN simulation tools