11,449 research outputs found
Applying Formal Methods to Networking: Theory, Techniques and Applications
Despite its great importance, modern network infrastructure is remarkable for
the lack of rigor in its engineering. The Internet which began as a research
experiment was never designed to handle the users and applications it hosts
today. The lack of formalization of the Internet architecture meant limited
abstractions and modularity, especially for the control and management planes,
thus requiring for every new need a new protocol built from scratch. This led
to an unwieldy ossified Internet architecture resistant to any attempts at
formal verification, and an Internet culture where expediency and pragmatism
are favored over formal correctness. Fortunately, recent work in the space of
clean slate Internet design---especially, the software defined networking (SDN)
paradigm---offers the Internet community another chance to develop the right
kind of architecture and abstractions. This has also led to a great resurgence
in interest of applying formal methods to specification, verification, and
synthesis of networking protocols and applications. In this paper, we present a
self-contained tutorial of the formidable amount of work that has been done in
formal methods, and present a survey of its applications to networking.Comment: 30 pages, submitted to IEEE Communications Surveys and Tutorial
Constraint-based specifications for system configuration
Declarative, object-oriented configuration management systems are widely used, and
there is a desire to extend such systems with automated analysis and decision-making.
This thesis introduces a new formulation for configuration management problems based
on the tools and techniques of constraint programming, which enables automated
decision-making.
We present ConfSolve, an object-oriented declarative configuration language, in
which logical constraints on a system can be specified. Verification, impact analysis,
and the generation of valid configurations can then be performed. This is achieved via
translation to the MiniZinc constraint programming language, which is in turn solved
via the Gecode constraint solver. We formally define the syntax, type system, and
semantics of ConfSolve, in order to provide it with a rigorous foundation. Additionally
we show that our implementation outperforms previous work, which utilised an SMT
solver, while adding new features such as optimisation.
We next develop an extension of the ConfSolve language, which facilitates not
only one-off configuration tasks, but also subsequent re-configurations in which the
previous state of the system is taken into account. In a practical setting one does not
wish for a re-configuration to deviate too far from the existing state, unless the benefits
are substantial. Re-configuration is of crucial importance if automated configuration
systems are to gain industry adoption. We present a novel approach to incorporating
state-change into ConfSolve while remaining declarative and providing acceptable
performance
Towards declarative diagnosis of constraint programs over finite domains
The paper proposes a theoretical approach of the debugging of constraint
programs based on a notion of explanation tree. The proposed approach is an
attempt to adapt algorithmic debugging to constraint programming. In this
theoretical framework for domain reduction, explanations are proof trees
explaining value removals. These proof trees are defined by inductive
definitions which express the removals of values as consequences of other value
removals. Explanations may be considered as the essence of constraint
programming. They are a declarative view of the computation trace. The
diagnosis consists in locating an error in an explanation rooted by a symptom.Comment: In M. Ronsse, K. De Bosschere (eds), proceedings of the Fifth
International Workshop on Automated Debugging (AADEBUG 2003), September 2003,
Ghent. cs.SE/030902
The KB paradigm and its application to interactive configuration
The knowledge base paradigm aims to express domain knowledge in a rich formal
language, and to use this domain knowledge as a knowledge base to solve various
problems and tasks that arise in the domain by applying multiple forms of
inference. As such, the paradigm applies a strict separation of concerns
between information and problem solving. In this paper, we analyze the
principles and feasibility of the knowledge base paradigm in the context of an
important class of applications: interactive configuration problems. In
interactive configuration problems, a configuration of interrelated objects
under constraints is searched, where the system assists the user in reaching an
intended configuration. It is widely recognized in industry that good software
solutions for these problems are very difficult to develop. We investigate such
problems from the perspective of the KB paradigm. We show that multiple
functionalities in this domain can be achieved by applying different forms of
logical inferences on a formal specification of the configuration domain. We
report on a proof of concept of this approach in a real-life application with a
banking company. To appear in Theory and Practice of Logic Programming (TPLP).Comment: To appear in Theory and Practice of Logic Programming (TPLP
Middleware for managing a large, heterogeneous programmable network
The links between BTexact Technologies and the Department of Computing Science at University College London are becomingincreasingly beneficial for the development of the middleware area for the management of programmable networks. This paperdescribes the work that has been done to date, and outlines the plans for future research
Investigating Decision Support Techniques for Automating Cloud Service Selection
The compass of Cloud infrastructure services advances steadily leaving users
in the agony of choice. To be able to select the best mix of service offering
from an abundance of possibilities, users must consider complex dependencies
and heterogeneous sets of criteria. Therefore, we present a PhD thesis proposal
on investigating an intelligent decision support system for selecting Cloud
based infrastructure services (e.g. storage, network, CPU).Comment: Accepted by IEEE Cloudcom 2012 - PhD consortium trac
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