Conditional Uncertainty in Constraint Networks

Last man standing: Static, decremental and dynamic resiliency via controller synthesis

“…Instead, focusing on resource controllability only, in [6], Zavatteri et al, proposed an initial approach to check weak, strong and dynamic controllability for access controlled workflows under conditional uncertainty by mapping workflow paths to constraint networks (CNs) [7] and reasoning on the intersection of common parts. The proposed approach pointed out that dynamic controllability might be a matter of how the components of the workflow are ordered, an hypothesis that was later confirmed by Zavatteri e Viganò in [8,9] with the proposal of constraint networks under conditional uncertainty (CNCUs). The experimental evaluations of CNCUs can be seen as evaluations for a conditional WSP (i.e., a WSP with uncontrollable XOR-splits considered).…”

“…Specifically, to guarantee a successful task to user assignment under conditional uncertainty that always satisfies a given set of security policies in [8,9] we build on [6] to provide constraint networks under conditional uncertainty (CNCUs) as an extension of classic constraint networks (CNs, [7]). CNCUs address natively conditional uncertainty by means of observation points in the workflow allowing us to observe the uncontrollable behavior (of the environment) revealing in real time which workflow path the execution will go through.…”

“…The experimental evaluations of CNCUs can be seen as evaluations for a conditional WSP (i.e., a WSP with uncontrollable XOR-splits considered). Having made such an assumption, the size of these conditional workflows provided in [8] ranges from 5 to 15 tasks (where 1 to 10 are uncontrollable XOR splits) and 10 to 30 authorized users for each task, whereas the workflows provided in [9] have a fixed number of 6 tasks with the same 6 users authorized for each task, no partial order and a number of XOR-splits ranging from 1 to 6 (this shows again that even small instances can be hard). In this paper we have seen that workflow resiliency shares with these latter works the matter of order.…”

Resource Controllability of Business Processes Under Conditional Uncertainty

“…A constraint network under conditional uncertainty (CNCU, [55,59,61])-the model we used in the previous version of this paper-is equivalent to a CCND where D = ∅, and = for each (X , Y , ) ∈ .…”

“…That approach maps WF paths to constraint networks (CNs, [14]), relies on directional consistency to guarantee no backtracking when generating any solution to the underlying constraints satisfaction problem [17], and reasons on the intersection of the common parts of the WF paths to achieve a dynamic execution of the ACWFs. However, dynamic controllability of ACWFs also depends on how the components of the ACWF are ordered [59,61]. In [51], the designer encodes manually an ACWF into a CN meaning that it is up to him to choose a suitable total order for each WF path such that these WF paths can be intersected in their common parts to rule out assignments of tasks to users that never satisfy any solution.…”