394 research outputs found
Predicting global usages of resources endowed with local policies
The effective usages of computational resources are a primary concern of
up-to-date distributed applications. In this paper, we present a methodology to
reason about resource usages (acquisition, release, revision, ...), and
therefore the proposed approach enables to predict bad usages of resources.
Keeping in mind the interplay between local and global information occurring in
the application-resource interactions, we model resources as entities with
local policies and global properties governing the overall interactions.
Formally, our model takes the shape of an extension of pi-calculus with
primitives to manage resources. We develop a Control Flow Analysis computing a
static approximation of process behaviour and therefore of the resource usages.Comment: In Proceedings FOCLASA 2011, arXiv:1107.584
A Quantitative Study of Two Attacks
We use a special operational semantics which helps us in predicting quantitative measures on systems describing cryptographic protocols: We also consider a possible attacker. The transitions of the system carry enhanced labels. We assign rates to transitions by only looking at these labels. We then map transition systems to Markov chains and evaluate performance of systems, using standard tools
Safer in the Clouds (Extended Abstract)
We outline the design of a framework for modelling cloud computing
systems.The approach is based on a declarative programming model which takes
the form of a lambda-calculus enriched with suitable mechanisms to express and
enforce application-level security policies governing usages of resources
available in the clouds. We will focus on the server side of cloud systems, by
adopting a pro-active approach, where explicit security policies regulate
server's behaviour.Comment: In Proceedings ICE 2010, arXiv:1010.530
Revealing the trajectories of KLAIM tuples, statically
Klaim (Kernel Language for Agents Interaction and Mobility) has been devised to design distributed applications composed by many components deployed over the nodes of a distributed infrastructure and to offer programmers primitive constructs for communicating, distributing and retrieving data. Data could be sensitive and some nodes could not be secure. As a consequence it is important to track data in their traversal of the network. To this aim, we propose a Control Flow Analysis that over-approximates the behaviour of Klaim processes and tracks how tuple data can move in the network
A Taxonomy of Causality-Based Biological Properties
We formally characterize a set of causality-based properties of metabolic
networks. This set of properties aims at making precise several notions on the
production of metabolites, which are familiar in the biologists' terminology.
From a theoretical point of view, biochemical reactions are abstractly
represented as causal implications and the produced metabolites as causal
consequences of the implication representing the corresponding reaction. The
fact that a reactant is produced is represented by means of the chain of
reactions that have made it exist. Such representation abstracts away from
quantities, stoichiometric and thermodynamic parameters and constitutes the
basis for the characterization of our properties. Moreover, we propose an
effective method for verifying our properties based on an abstract model of
system dynamics. This consists of a new abstract semantics for the system seen
as a concurrent network and expressed using the Chemical Ground Form calculus.
We illustrate an application of this framework to a portion of a real
metabolic pathway
Choreography Rehearsal ⋆
Abstract. We propose a methodology for statically predicting the possible interaction patterns of services within a given choreography. We focus on choreographies exploiting the event notification paradigm to manage service interactions. Control Flow Analysis techniques statically approximate which events can be delivered to match the choreography constraints and how the multicast groups can be optimised to handle event notification within the service choreography.
A Flat Process Calculus for Nested Membrane Interactions
The link-calculus has been recently proposed as a process calculus for representing interactions that are open (i.e., that the number of processes may vary), and multiparty (i.e., that may involve more than two processes). Here, we apply the link-calculus for expressing, possibly hierarchical and non dyadic, biological interactions. In particular, we provide a natural encoding of Cardelli's Brane calculus, a compartment-based calculus, introduced to model the behaviour of nested membranes. Notably, the link-calculus is flat, but we can model membranes just as special processes taking part in the biological reaction. Moreover, we give evidence that the link-calculus allows one to directly model biological phenomena at the more appropriate level of abstraction
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