327 research outputs found
Secure Cloud-Edge Deployments, with Trust
Assessing the security level of IoT applications to be deployed to
heterogeneous Cloud-Edge infrastructures operated by different providers is a
non-trivial task. In this article, we present a methodology that permits to
express security requirements for IoT applications, as well as infrastructure
security capabilities, in a simple and declarative manner, and to automatically
obtain an explainable assessment of the security level of the possible
application deployments. The methodology also considers the impact of trust
relations among different stakeholders using or managing Cloud-Edge
infrastructures. A lifelike example is used to showcase the prototyped
implementation of the methodology
Event-driven Adaptation in COP
Context-Oriented Programming languages provide us with primitive constructs
to adapt program behaviour depending on the evolution of their operational
environment, namely the context. In previous work we proposed ML_CoDa, a
context-oriented language with two-components: a declarative constituent for
programming the context and a functional one for computing. This paper
describes an extension of ML_CoDa to deal with adaptation to unpredictable
context changes notified by asynchronous events.Comment: In Proceedings PLACES 2016, arXiv:1606.0540
A Context-Oriented Extension of F#
Context-Oriented programming languages provide us with primitive constructs
to adapt program behaviour depending on the evolution of their operational
environment, namely the context. In previous work we proposed ML_CoDa, a
context-oriented language with two-components: a declarative constituent for
programming the context and a functional one for computing. This paper
describes the implementation of ML_CoDa as an extension of F#.Comment: In Proceedings FOCLASA 2015, arXiv:1512.0694
Typing Context-Dependent Behavioural Variation
Context Oriented Programming (COP) concerns the ability of programs to adapt
to changes in their running environment. A number of programming languages
endowed with COP constructs and features have been developed. However, some
foundational issues remain unclear. This paper proposes adopting static
analysis techniques to reason on and predict how programs adapt their
behaviour. We introduce a core functional language, ContextML, equipped with
COP primitives for manipulating contexts and for programming behavioural
variations. In particular, we specify the dispatching mechanism, used to select
the program fragments to be executed in the current active context. Besides the
dynamic semantics we present an annotated type system. It guarantees that the
well-typed programs adapt to any context, i.e. the dispatching mechanism always
succeeds at run-time.Comment: In Proceedings PLACES 2012, arXiv:1302.579
Automata for specifying and orchestrating service contracts
An approach to the formal description of service contracts is presented in
terms of automata. We focus on the basic property of guaranteeing that in the
multi-party composition of principals each of them gets his requests satisfied,
so that the overall composition reaches its goal. Depending on whether requests
are satisfied synchronously or asynchronously, we construct an orchestrator
that at static time either yields composed services enjoying the required
properties or detects the principals responsible for possible violations. To do
that in the asynchronous case we resort to Linear Programming techniques. We
also relate our automata with two logically based methods for specifying
contracts
Two Design Procedures for PM Synchronous Machines for Electric Powertrains
This paper presents a design environment for permanent-magnet synchronous motors (PMSMs). Two design examples for electric vehicle (EV) traction are presented: one interior PM machine of the PM-assisted synchronous reluctance (PM-SyR) type and one concentrated-winding surface-mounted PM motor (CW-SPM). The parametric design software used in the paper includes design equations, finite element analysis (FEA) and multi-objective optimization algorithms for the design of PMSMs. The paper presents two possible design methodologies, for the two mentioned test cases. EV application was chosen for its many challenging aspects, involving flux weakening for extended speed range, discontinuous duty cycles, high transient overload requirements, high efficiency over a large area of operation, and so forth. The design examples are compared to selected benchmark designs in terms of operating range in the torque versus speed domain and efficiency maps, all FEA evaluated. Besides magnetics, thermal and structural aspects are included in the study
Checking global usage of resources handled with local policies
We present a methodology to reason about resource usage (acquisition, release, revision, and so on) and, in particular, to predict bad usage of resources. Keeping in mind the interplay between local and global information that occur in application-resource interactions, we model resources as entities with local policies and we study global properties that govern overall interactions. Formally, our model is an extension of π-calculus with primitives to manage resources. To predict possible bad usage of resources, we develop a Control Flow Analysis that computes a static over-approximation of process behaviour
From Orchestration to Choreography through Contract Automata
We study the relations between a contract automata and an interaction model.
In the former model, distributed services are abstracted away as automata -
oblivious of their partners - that coordinate with each other through an
orchestrator. The interaction model relies on channel-based asynchronous
communication and choreography to coordinate distributed services.
We define a notion of strong agreement on the contract model, exhibit a
natural mapping from the contract model to the interaction model, and give
conditions to ensure that strong agreement corresponds to well-formed
choreography.Comment: In Proceedings ICE 2014, arXiv:1410.701
Secure FaaS orchestration in the fog: how far are we?
AbstractFunction-as-a-Service (FaaS) allows developers to define, orchestrate and run modular event-based pieces of code on virtualised resources, without the burden of managing the underlying infrastructure nor the life-cycle of such pieces of code. Indeed, FaaS providers offer resource auto-provisioning, auto-scaling and pay-per-use billing at no costs for idle time. This makes it easy to scale running code and it represents an effective and increasingly adopted way to deliver software. This article aims at offering an overview of the existing literature in the field of next-gen FaaS from three different perspectives: (i) the definition of FaaS orchestrations, (ii) the execution of FaaS orchestrations in Fog computing environments, and (iii) the security of FaaS orchestrations. Our analysis identify trends and gaps in the literature, paving the way to further research on securing FaaS orchestrations in Fog computing landscapes
Last Mile’s Resources
We extend an existing two-phase static analysis for an adaptive programming language to also deal with dynamic resources. The focus of our analysis is on predicting how these are used, in spite of the different, ever changing operating environments to which applications automatically adapt their behaviour. Our approach is based on a type and effect system at compile time, followed by a control flow analysis carried on at loading time. Remarkably, the second analysis cannot be anticipated, because information about availability, implementation and
other aspects of resources are unknown until the application is injected in the current environment
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