Biblio

We present a new paradigm for unification arising out of a technique commonly used in cryptographic protocol analysis tools that employ unification modulo equational theories. This paradigm relies on: (i) a decomposition of an equational theory into (R, E) where R is confluent, terminating, and coherent modulo E, and (ii) on reducing unifi- cation problems to a set of problems s =^? t under the constraint that t remains R/E-irreducible. We call this method asymmetric unification . We first present a general-purpose generic asymmetric unification algorithm.and then outline an approach for converting special-purpose conventional unification algorithms to asymmetric ones, demonstrating it for exclusive-or with uninterpreted function symbols. We demonstrate how asymmetric unification can improve performanceby running the algorithm on a set of benchmark problems. We also give results on the complexity and decidability of asymmetric unification.

Conventional wisdom is that the textbook view describes reality, and only bad people (not good people trying to get their jobs done) break the rules. And yet it doesn't, and good people circumvent.
 

We have been studying extension of the classical Software Reliability Engineering (SRE) methodology into the security space. We combine “classical” reliability modeling, when applied to reported vulnerabilities found under “normal” operational profile conditions, with safety oriented fault management processes. We illustrate with open source Fedora software.

Our initial results appear to indicate that generation of a repeatable automated test-strategy that would explicitly cover the “top 25” security problems may help considerably – eliminating perhaps as much as 50% of the field observable problems. However, genuine aleatoric and more process oriented incomplete analysis and design flaws remain. While we have made some progress in identifying focus areas, a number of questions remain, and we continue working on them.

The goal of this roadmap paper is to summarize the stateof-the-art and identify research challenges when developing, deploying and managing self-adaptive software systems. Instead of dealing with a wide range of topics associated with the field, we focus on four essential topics of self-adaptation: design space for self-adaptive solutions, software engineering processes for self-adaptive systems, from centralized to decentralized control, and practical run-time verification & validation for self-adaptive systems. For each topic, we present an overview, suggest future directions, and focus on selected challenges. This paper complements and extends a previous roadmap on software engineering for self-adaptive systems published in 2009 covering a different set of topics, and reflecting in part on the previous paper. This roadmap is one of the many results of the Dagstuhl Seminar 10431 on Software Engineering for Self-Adaptive Systems, which took place in October 2010.

Mixing the actor model with other concurrency models in a single program can break the actor abstraction. This increases the chance of creating deadlocks and data races—two mistakes that are hard to make with actors. Furthermore, it prevents the use of many advanced testing, modeling, and verification tools for actors, as these require pure actor programs. This study is the first to point out the phenomenon of mixing concurrency models by Scala developers and to systematically identify the factors leading to it. We studied 15 large, mature, and actively maintained actor programs written in Scala and found that 80% of them mix the actor model with another concurrency model. Consequently, a large part of real-world actor programs does not use actors to their fullest advantage. Inspection of the programs and discussion with the developers reveal two reasons for mixing that can be influenced by researchers and library-builders: weaknesses in the actor library implementations, and shortcomings of the actor model itself.

Demand ResponseManagement (DRM) is a key component in the smart grid to effectively reduce power generation costs and user bills. However, it has been an open issue to address the DRM problem in a network of multiple utility companies and consumers where every entity is concerned about maximizing its own benefit. In this paper, we propose a Stackelberg game between utility companies and end-users to maximize the revenue of each utility company and the payoff of each user. We derive analytical results for the Stackelberg equilibrium of the game and prove that a unique solution exists.We develop a distributed algorithm which converges to the equilibrium with only local information available for both utility companies and end-users. Though DRM helps to facilitate the reliability of power supply, the smart grid can be succeptible to privacy and security issues because of communication links between the utility companies and the consumers. We study the impact of an attacker who can manipulate the price information from the utility companies.We also propose a scheme based on the concept of shared reserve power to improve the grid reliability and ensure its dependability.

Since conventional software security approaches are often manually developed and statically deployed, they are no longer sufficient against today's sophisticated and evolving cyber security threats. This has motivated the development of self-protecting software that is capable of detecting security threats and mitigating them through runtime adaptation techniques. In this paper, we argue for an architecture-based self- protection (ABSP) approach to address this challenge. In ABSP, detection and mitigation of security threats are informed by an architectural representation of the running system, maintained at runtime. With this approach, it is possible to reason about the impact of a potential security breach on the system, assess the overall security posture of the system, and achieve defense in depth. To illustrate the effectiveness of this approach, we present several architecture adaptation patterns that provide reusable detection and mitigation strategies against well-known web application security threats. Finally, we describe our ongoing work in realizing these patterns on top of Rainbow, an existing architecture-based adaptation framework.

The simplest and purest practical object-oriented language designs today are seen in dynamically-typed languages, such as Smalltalk and Self. Static types, however, have potential benefits for productivity, security, and reasoning about programs. In this paper, we describe the design of Wyvern, a statically typed, pure object-oriented language that attempts to retain much of the simplicity and expressiveness of these iconic designs.

Our goals lead us to combine pure object-oriented and functional abstractions in a simple, typed setting. We present a foundational object-based language that we believe to be as close as one can get to simple typed lambda calculus while keeping object-orientation. We show how this foundational language can be translated to the typed lambda calculus via standard encodings. We then define a simple extension to this language that introduces classes and show that classes are no more than sugar for the foundational object-based language. Our future intention is to demonstrate that modules and other object-oriented features can be added to our language as not more than such syntactical extensions while keeping the object-oriented core as pure as possible.

The design of Wyvern closely follows both historical and modern ideas about the essence of object-orientation, suggesting a new way to think about a minimal, practical, typed core language for objects.