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

Generating collaborative systems for digital libraries: A model-driven approach

This is an open access article shared under a Creative Commons Attribution 3.0 Licence (http://creativecommons.org/licenses/by/3.0/). Copyright @ 2010 The Authors.The design and development of a digital library involves different stakeholders, such as: information architects, librarians, and domain experts, who need to agree on a common language to describe, discuss, and negotiate the services the library has to offer. To this end, high-level, language-neutral models have to be devised. Metamodeling techniques favor the definition of domainspecific visual languages through which stakeholders can share their views and directly manipulate representations of the domain entities. This paper describes CRADLE (Cooperative-Relational Approach to Digital Library Environments), a metamodel-based framework and visual language for the definition of notions and services related to the development of digital libraries. A collection of tools allows the automatic generation of several services, defined with the CRADLE visual language, and of the graphical user interfaces providing access to them for the final user. The effectiveness of the approach is illustrated by presenting digital libraries generated with CRADLE, while the CRADLE environment has been evaluated by using the cognitive dimensions framework

Event-driven grammars: Relating abstract and concrete levels of visual languages

The final publication is available at Springer via http://dx.doi.org/10.1007/s10270-007-0051-2In this work we introduce event-driven grammars, a kind of graph grammars that are especially suited for visual modelling environments generated by meta-modelling. Rules in these grammars may be triggered by user actions (such as creating, editing or connecting elements) and in their turn may trigger other user-interface events. Their combination with triple graph transformation systems allows constructing and checking the consistency of the abstract syntax graph while the user is building the concrete syntax model, as well as managing the layout of the concrete syntax representation. As an example of these concepts, we show the definition of a modelling environment for UML sequence diagrams. A discussion is also presented of methodological aspects for the generation of environments for visual languages with multiple views, its connection with triple graph grammars, the formalization of the latter in the double pushout approach and its extension with an inheritance concept.This work has been partially sponsored by the Spanish Ministry of Education and Science with projects MOSAIC (TSI2005-08225-C07-06) and MODUWEB (TIN 2006-09678)

Specification Patterns for Robotic Missions

Mobile and general-purpose robots increasingly support our everyday life, requiring dependable robotics control software. Creating such software mainly amounts to implementing their complex behaviors known as missions. Recognizing the need, a large number of domain-specific specification languages has been proposed. These, in addition to traditional logical languages, allow the use of formally specified missions for synthesis, verification, simulation, or guiding the implementation. For instance, the logical language LTL is commonly used by experts to specify missions, as an input for planners, which synthesize the behavior a robot should have. Unfortunately, domain-specific languages are usually tied to specific robot models, while logical languages such as LTL are difficult to use by non-experts. We present a catalog of 22 mission specification patterns for mobile robots, together with tooling for instantiating, composing, and compiling the patterns to create mission specifications. The patterns provide solutions for recurrent specification problems, each of which detailing the usage intent, known uses, relationships to other patterns, and---most importantly---a template mission specification in temporal logic. Our tooling produces specifications expressed in the LTL and CTL temporal logics to be used by planners, simulators, or model checkers. The patterns originate from 245 realistic textual mission requirements extracted from the robotics literature, and they are evaluated upon a total of 441 real-world mission requirements and 1251 mission specifications. Five of these reflect scenarios we defined with two well-known industrial partners developing human-size robots. We validated our patterns' correctness with simulators and two real robots

Multilingual media components directly embeddable in open educational resources in science and technology

The use and reuse of OER (Open Educational Resources) depends on several conditions. Amongst others, the richness of their metadata, their granularity and the languages ​​in which they are made available. This work aims to facilitate efficient production of graphical and language-neutral components. It is assumed that the STEM areas (Science, Technology, Engeneering and Mathematics) share a common mathematical language and, more intuitively, an iconographic approach linked to the structures that satisfy the formulas used in each case. The work is limited to these areas of knowledge, primarily as presentations and animations of very low granularity, which can be directly integrated into larger resources in any language. The overall research design consists of four stages: 1. Initially, the manual generation of presentations and animations, with no literal in any language, and very concisely focused (mainly, definitions of a single concept for each animation). Determination of common graphics primitives to differentiate the common subtasks: presentation of examples to make the concept emerge inductively, graphical construction of the definition, highlighting the generalization or instantiation steps, homogeneous use of icons for emphasising or posing a question to the observer .. . 2. Evaluation of the expressiveness and effectiveness of these resources. Currently, these resources are being presented to small groups of students. This fall begins a multilingual evaluation process on a larger scale: as part of a regular course at the UNED and as LabSpace course in the Open University. Here we attempt to clarify the appropriate assessment tools (preferably in the same graphics language) with the minimum amount of additional external comments to constitute a course in a particular language. 3. The first two stages must provide an intuitive and graphical interface of the selected formalism (mainly Discrete Mathematics and Logic). The third stage addresses the effect of changing the output device on the selection of the graphics primitives for each generic subtask. Possible variations of the graphical language will be studied in the context of HCI analyses. 4. Finally the approach addresses semi-automatic generation, via script, of these resources: from formal description of the definitions or processes (as described, for example, in OMDoc) to the production of the corresponding animation. Additionally, the injection of semantics should facilitate the link between different animations, the navigation and search of conceptual dependency and the identification of concepts that have supporting collections of resources as described. At this point, the current development of this work provides results for the first two stages described