Section: New Results

Data driven systems

A model of large-scale distributed collaborative system

Participants : Éric Badouel, Loïc Hélouët, Christophe Morvan, Robert Nsaibirni.

We have presented in [27] and  [18] a purely declarative approach to artifact-centric collaborative systems, a model which we introduced in two stages. First, we assume that the workspace of a user is given by a mindmap, shortened to a map, which is a tree used to visualize and organize tasks in which he or she is involved, together with the information used for the resolution of these tasks. We introduce a model of guarded attribute grammar, or GAG, to help the automation of updating such a map. A GAG consists of an underlying grammar, that specifies the logical structure of the map, with semantic rules which are used both to govern the evolution of the tree structure (how an open node may be refined to a subtree) and to compute the value of some of the attributes (which derives from con-textual information). The map enriched with this extra information is termed an active workspace. Second, we define collaborative systems by making the various user's active workspaces communicate with each other. The communication uses message passing without shared memory thus enabling convenient distribution on an asynchronous architecture. A case study on a disease surveillance system is under development in the PhD thesis of Robert Nsaibirni and a first prototype of the model of active workspaces was written by Eric Badouel.

Petri Nets with semi-structured data

Participants : Éric Badouel, Loïc Hélouët, Christophe Morvan.

In [28] , we have proposed an extension of Petri nets with data called Structured Data Nets (StDN). This extension allows for the description of transactional systems with data. In StDNs, tokens are structured documents. Each transition is attached to a query, guarded by patterns, (logical assertions on the contents of its preset) and transforms tokens. In [28] , we have proposed a semantics for StDNs, and then considered their formal properties: coverability of a marking, termination and soundness of transactions. Unrestricted StDNs are Turing complete, so these properties are undecidable. However, we have proposed an order on structured documents, and shown that under reasonable restrictions on documents and on the ex- pressiveness of patterns and queries, StDNs are well-structured transition systems, for which coverability, termination and soundness are decidable. This work has then been extended to consider properties of sets of configurations described as upward closed sets satisfying patterns, and should appear in a journal paper in 2016.