Bigraphs and (Reactive) XML: an XML-centric model of computation

XML-centric models of computation have been proposed as an answer to the demand for interoperability, heterogeneity and openness in coordination models.

Recently, Bigraphical reactive systems has been introduced as a theoretical meta-model for reactive} systems with semi-structured state. We present an XML representation of bigraphical reactive systems called Reactive XML. It may be seen as an open, XML-centric model of computation with a solid theoretical foundation given by the theory of bigraphical reactive systems. In particular, the theory provides a formal denotation of composition and general transformations of XML documents with links. On the other hand, Reactive XML provides a concrete understanding of the theoretical model of bigraphical reactive systems. We report on a prototype for Reactive XML, describing how Reactive XML reactions can be carried out in praxis. In particular, we describe how the abstract notion of evaluation contexts may be represented concretely (and generalised) by XPath expressions. The prototype is currently being extended to a distributed setting, ultimately allowing distributed XML-centric applications to coordinate through computations on shared XML data.