October 21, 2008.

Bigraphical Business Processes Execution

Abstract.

The model of Bigraphical Reactive Systems (BRSs) has been proposed by Milner as a formal meta-model for global ubiquitous computing that encompasses process calculi for mobility, notably the π-calculus and the Mobile Ambients calculus, as well as graphical models for concurrency such as Petri Nets.

In this presentation we demonstrate that BRSs also allow natural formalizations of languages used in practice by providing a direct and extensible formalization of a subset of WS-BPEL as a binding bigraphical reactive system.

The formalization exploits the close correspondence between bigraphs and XML to provide a formalization and execution format very close to standard WS-BPEL syntax.

In the talk we will comment on the potential use of the BRS metamodel to relate different formalizations of BPEL, for instance formalizations based on Petri Net, the π-calculus or the more direct bigraphical representation of the BPEL syntax as in the presented formalization.

We will also comment on its use to provide a completely formalized and extensible business process engine within the Computer Supported Mobile Adaptive Business Processes (www.CosmoBiz.org) research project at the IT University of Copenhagen.

Building upon the formalization of WS-BPEL we have at COORDINATION 2008 proposed and formalized HomeBPEL, a higher-order WS-BPEL-like business process execution language where processes are first-class values that can be stored in variables, passed as messages, and activated as embedded sub-instances. A sub-instance is similar to a WS-BPEL scope, except that it can be dynamically frozen and stored as a process in a variable, and then subsequently be thawed when reactivated as a sub-instance.

The formalization has been implemented in the BPL-Tool developed in the Bigraphical Programming Languages (BPL) project. The tool allows for compositional definition, visualization and simulation of the execution of bigraphical reactive systems.