The growth of mobile data traffic is urging on the development of mechanisms to route cellular traffic through alternative networks. In this paper, we present an approach to do mobile data offloading from/to vehicular ad hoc networks (VANETs), grounded on a virtualization layer and a new routing protocol on top of it. The virtualization layer deals with the issues derived from the mobility of the vehicles, offering the view of a network of stationary virtual nodes. In turn, the routing protocol puts forward a new combination of topological and geographical routing, which can consistently achieve better performance than state-of-the-art approaches to VANET routing in simulations of urban scenarios with different vehicle densities.

Intersection-based geographical routing algorithms have become predominant in the realm of vehicular ad-hoc networks (VANETs), with forwarding strategies that create road-based paths a way to avoid dead ends and to prevent losses due to the presence of buildings. However, there remain problems associated to the location service that must be in place to provide accurate location data of the destination nodes. In this paper, we present a new routing algorithm called VNIBR that puts forward an efficient combination of topological and geographical routing, getting rid of the location service. This algorithm is based on a virtualization layer that allows decoupling routing logic from node identities in a radically different way. We prove by means of simulations that VNIBR consistently ensures moderate overhead and good packet delivery ratios in comparison with state-of-the-art approaches to VANET routing in urban scenarios with different vehicle densities.

Over the last few years, we have witnessed a generalization of the consumption of video contents through different media (computers, television, mobile phones, tablets,…) that converge into a unified user experience in an (almost) all-IP technological environment. At the same time, there have been significant advances in the generation and characterization of multimedia contents, due to the advent of social networking and the consolidation of standards like moving picture experts group (MPEG)-4 and MPEG-7. Finally, it is becoming easier and more natural to interact with multimedia contents, thanks to devices like tactile screens and touchpads. Overall, this landscape enables great possibilities for advertising and e-commerce, far beyond the traditional business models of broadcast TV. In this paper, we present a novel realization of two non-invasive advertising and e-commerce models to exploit those possibilities, grounded on a cloud-based personalization engine. This system cannot only identify the most interesting products to advertise to each user at any time, but also compose personalized applications on the fly, ready to run on different consumer device platforms. Our experiments show that this proposal can be very positively perceived by the end users.

The great acceptation of the Social Web has converted social networks, blogs and wikis in almost perfect advertising mediums. However, many of the current social publicity strategies do not exploit all the potential of these mediums, since they obviate users' online life: the social contexts in which they are involved. Our proposal to reverse this situation is a model to infer users' social contexts by the application of several Natural Language Processing (NLP) and data mining techniques over users' interaction data on Facebook. We take advantage of both Facebook and Groupon APIs to provide a deployment scenario in which knowing users' social life allows ads to target the most potential customers, which is beneficial for both companies and possible customers.

Virtual mobile nodes (VMNs) were recently introduced as a means to address the challenges raised by the mobility of the nodes in ad hoc networks. This concept can be readily applied in the specific realm of VANETs, taking advantage of the facts that the movements of the vehicles are bound to the road and street maps, and that the variation of vehicle density has statistical behavior in time and space. Several studies have proved that VMNs can facilitate the planning of communications among the vehicles that travel through a given area. We introduce the concept of virtual virtual circuits (VVCs) as a means to reduce even further the number of control packets flowing through the VANETs and the computational load on the communication devices. Early results are presented that evidence significant improvements in terms of delay, packet losses and throughput.

In the new technological context of interactive digital (IDTV), traditional TV spots are expected to be replaced by interactive applications. In this paper, we propose a new TV advertising architecture inspired by the philosophy and business models of online advertising. Personalization and content awareness are the two mainstays of our approach that allow advertisers to have more efficient campaigns focused on a targeted audience.

The implantation of the European Higher Education Area pursues a profound renewal of the teaching methodologies, emphasizing the role of ICTs to enable possibilities of continuous, lifelong learning. We describe a pioneering project in the application of Interactive Digital TV technologies to higher education, as a means to facilitate the understanding of concepts taught at the Telecommunication Engineering School of the University of Vigo. Preliminary experiences with volunteer students reveal the pedagogical and motivating value of the proposed approach, yielding useful observations for the application of the t-learning paradigm in other areas.

One of the main ideas of agile development is to perform continuous integration, in order to detect and resolve conflicts among several modular units of a system as soon as possible. Whereas this feature is well catered for at the level of programming source code, the support available in formal specification environments is still rather unsatisfactory: it is possible to analyze the composition of several modular units automatically, but no assistance is given to help modify them in case of problems. Instead, the stakeholders who build the specifications are forced to attempt manual changes until reaching the desired functionality, in a process that is far from being intuitive. In response to that, this paper presents procedures and algorithms that automate the whole process of doing integration analyses and generating revisions to solve the diagnosed problems. These mechanisms serve to complete an agile specification environment presented in a previous paper, which was designed around the principle of facilitating the creative efforts of the stakeholders.

When multiple mobile devices are brought together into an ad-hoc network, some kind of coordination is usually needed to ensure the fulfillment of the network's global objectives. In literature, there exist various approaches to carry out that coordination. However, those approaches have not been validated satisfactorily, because previous studies paid very little attention to how well the networks do perform the tasks for which they are deployed. To tackle this issue, we present the design of a simulator for the assessment of coordination policies, with the well-known capabilities of ns-2 for the networking issues, plus an eye on overall performance in the application domain.

The development of digital television for mobile devices brings in new possibilities for informal learning, by means of interactive educational services linked to the TV programs. Some systems exist in the m-learning literature that may automatically discover the most valuable services for each viewer at any time, matching information about his/her interests, context and needs, about the services available and about the TV programs that those services may be linked to. Most commonly, however, the reasoning process is performed by remote servers, which implies that the personalization features become unavailable in the frequent cases of sporadic or null access to a bidirectional communication channel. The alternative exists to do local reasoning in the mobile devices, but their limited computational power results in low personalization quality. In this paper, we solve these problems with a scalable approach to perform semantic reasoning in mobile devices, backed up by the bandwidth and robustness of the same broadcast networks that deliver the TV programs.

One of the main needs when dealing with multi-perspective specifications is to be able to have at our disposal, at intermediate stages of the development process, a merged view which properly reflects the knowledge of each participant in the elicitation tasks (and over which we can reason, even in the presence of disagreement and incompleteness). We show in this paper to what extent there can be many merged models, having all of them useful application. So there is not a unique operator which can be qualified as the best; on the contrary, there will be a suitable merging operator depending on the goal of the merging process. More concretely, we will propose a set of four composition operators: ∐max, ∐min, ∐majand ∐maj + inc. They will be evaluated making use of a list of desired algebraic properties proposed by researchers on merging and which should be held by an ideal merging operator. This analysis can help us to compare the different operators, revealing the key features of each, and identifying weaknesses that may require further research. The conclusion drawn after this analysis points out that these properties are not useful enough to adequately characterize a merging operator. Therefore, new properties will be provided in order to complete the previous list and help to define better the behavior of the different merging operators.

Abstract Digital Television will bring a significant increase in the amount of channels and programs available to end users, with many more difficulties to find contents appealing to them among a myriad of irrelevant information. Thus, automatic content recommenders should receive special attention in the following years to improve their assistance to users. The current content recommenders have important deficiencies that hamper their wide acceptance. In this paper, we present a new approach for automatic content recommendation that significantly reduces those deficiencies. This approach, based on Semantic Web technologies, has been implemented in the AdVAnced Telematic search of Audiovisual contents by semantic Reasoning tool, a hybrid content recommender that makes extensive use of well‐known standards, such as Multimedia Home Platform, TV‐Anytime and OWL. Also, we have carried out an experimental evaluation, the results of which show that our proposal performs better than other existing approaches. Copyright © 2007 John Wiley & Sons, Ltd.

This paper presents a practical approach to manage mobile ad-hoc networks around the service requirements of their forming hosts. The solution consists of a middleware layer called KEPPAN, designed to exploit incomplete and changeable information about virtually any aspect that influences service provision. Having formal languages at the interfaces with the networking and application levels, this approach represents a step towards autonomic, self-managed networks of mobile devices, in expectation of further advances in software engineering and artificial intelligence. Preliminary evaluation results are reported.

The generalized arrival of Digital TV will lead to a significant increase in the amount of channels and programs available to end users, making it difficult to find interesting programs among a myriad of irrelevant contents. Thus, in this field, automatic content recommenders should receive special attention in the following years to improve assistance to users. Current approaches of content recommenders have significant well-known deficiencies that hamper their wide acceptance. In this paper, a new approach for automatic content recommendation is presented that considerably reduces those deficiencies. This approach, based on the so-called Semantic Web technologies, has been implemented in the AVATAR tool, a hybrid content recommender that makes extensive use of well-known standards, such as TV-Anytime and OWL. Our proposal has been evaluated experimentally with real users, showing significant increases in the recommendation accuracy with respect to other existing approaches.

The possibility of transmitting interactive applications along with the audiovisual contents will turn the television into a universal platform to access the information society. Nowadays, there is growing interest in exploiting that potential to develop distance learning policies, to supplement the facilities offered by the current e-learning technologies. This short paper describes the implementation of a software module that enables the provision of educational services over interactive digital TV (T-learning). This module has been designed according to the technical peculiarities of an IDTV receiver, and resorts to existing standards to favor the convergence of all distance learning mediums

Content personalization is a very important aspect in the field of e-learning, although current standards do not fully support it. In this paper, we outline an extension to the ADL SCORM (Sharable Content Object Reference Model) standard in an effort to permit a suitable adaptivity based on user's characteristics. Applying this extension, we can create adaptable courses, which should be personalized before shown to the student.

Software development can be seen as a process of knowledge acquisition, in which human beings progressively learn about the intended behavior of the desired systems. Thereby, development is subject to considerable amounts of uncertainty and variability, that make it impossible to proceed in a purely incremental fashion — at some points, the need always arises to reconsider part of the accumulated knowledge. With this problem in mind, agile development methodologies have been gaining popularity in recent years as a means to enhance productivity, and there have been attempts to supplement them with formal techniques for better reliability. However, the existing approaches to agile formal methods have practically limited themselves to adopting recommended practices of agile development, with no particular contribution from the employed formalisms. Compared to that, this paper advocates the use of formalisms intended for evolutionary development, with a two-fold objective: first, to exploit the knowledge acquired up to any given stage as a means to cope with frequent and numerous changes; and, second, to introduce support for the creative development tasks through an interactive procedure that helps taking steps forward.

The development of requirements specifications is characterized by the uncertain and changeable knowledge available about the systems to be built. This paper presents a many-valued logic that enables effective reasoning about uncertainty and inconsistency in requirements specifications, motivating the election of six truth values and the definition of a new implication connective. The adequacy of this logic to support a formal development methodology is assessed through a comparison with Belnap's four-valued logic in combination with the classical implications.

Abstract The increasing need of the developed countries to carry out effective distance learning strategies has led to a great development of Internet‐based learning technologies (e‐learning). Despite its evident advantages, the expansion of e‐learning has been limited by the difficulty in reaching important social sectors, and also by the absence of mechanisms to fight the feeling of isolation of the users, which often leads them to abandoning the distance learning activities. This paper tackles these problems by introducing ATLAS, a framework for the development and deployment of multiuser t‐learning services (i.e. learning services over Interactive Digital TV). This framework is built around three major features: an architecture for the services that exploits the multimedia capabilities of the television, a communications infrastructure that promotes the establishment of virtual learning communities, and a development tool that allows services to be created with minimum programming knowledge. ATLAS has been designed by considering several features that make Interactive Digital TV quite different from the PC, advising against the direct translation of the models developed for the Internet. In particular, ATLAS adheres to the Multimedia Home Platform (MHP) standard, which is gaining worldwide acceptance as one of the technical solutions that will shape the future of Interactive Digital TV. Copyright © 2006 John Wiley & Sons, Ltd.

Abstract Nowadays, we are living in a time of important technological changes that affect our lives at home and our communication with the outside world. Among them, the developments in Interactive Digital TV (IDTV) and the smart home field can be considered as particularly important. Related to the former, the new Set‐Top Boxes (STBs) are not only a decoder for digital television broadcast but also an entry point to the Information Society and a suitable platform to support the execution of interactive applications. With regards to the latter, the Residential Gateways (RGs) combine different network technologies to allow the connection of different electronics devices and appliances at home, not only with each other but also with the Internet. Since there is no widespread consensus about the configurations and functions of the RGs, we propose to coordinate the two aforementioned worlds by extending the functionality of STBs to become a RG. Our proposal consists of merging the Multimedia Home Platform (MHP), one of the main standard frameworks for IDTV, with Open Service Gateway Initiative (OSGi), the most widely used open platform to set up RGs. To overcome the radically different nature of these specifications—the function‐oriented MHP middleware and the service‐oriented OSGi framework—we define a new kind of application, coined as XbundLET. This application is able to bridge the gap between the two frameworks and make their interaction feasible. We also show how this proposal has the potential to enable the production of scenarios that cannot currently be put into practice in a natural way. Copyright © 2006 John Wiley & Sons, Ltd.

In a totally formalized, iterative and incremental software process, each iteration usually implies identifying new requirements, adding them to the current model of the system, checking again the consistency and, in many cases, modifying the model to satisfy all the functional requirements. In this context, the ARIFS (Approximate Retrieval of Incomplete and Formal Specifications) methodology provides a suitable reuse environment (1) to classify, retrieve and adapt formal and incomplete requirements specifications and (2) to reuse the formal verification results linked to them. In this paper, we focus on the first goal describing the classification and retrieval tasks, which are based on functional similarities according to structural and semantic closeness. To this effect, we define four partial ordering relations among reusable components and several measures to quantify functional differences among them. By using these measures, we are able to offer an approximate and efficient retrieval, without formal proofs, and to predict adaptation efforts to satisfy the required functionality.

This paper presents several enhancements to ARIFS, a reuse environment that sets the foundations for reusing formal verification efforts in an iterative and incremental software process for the design of distributed reactive systems. A criterion based on generic components is added, together with a self-learning mechanism, to reduce the search space and maximize the probability of retrieving useful information. Besides, a formalization is given on how to apply verification tasks on a reduced number of states when the retrieved information is not enough for the user's intents. These enhancements are shown to improve both the effectiveness and the efficiency of ARIFS.

We adapt an analysis-revision cycle to SCTL-MUS methodology to support the modification and evolution of requirements specifications in a multiperspective environment. To illustrate the advantages of using our approach in the analysis and revision phases, we employ two viewpoints of a thermostat system. Both viewpoints are merged in order to reason over the properties of the composed system. The refinements over the merged model are transferred into each of the viewpoints and then into the requirements in which both are expressed. In this way, we obtain requirements refinements close to the system domain of each viewpoint, facilitating to the stakeholders the decision of what system requirements refinements must be included in the system requirements specification.

Achievement of quality in software design, while never easy, is made more difficult by the inherent complexity of hard real-time (HRT) design. Furthermore, timing requirements in HRT are by nature functional requirements, since system correctness depends on their fulfillment. Whereas the correctness dependence of the time imposes considering timing requirements from the early stages of the production process, complexity enforces a lifecycle model which fits in with requirements change and splits complexity by means of an incremental and iterative structure. Taking these aims as a starting point, this paper introduces SCTL/MUS-T methodology as supporting HRT design in a formalized and incremental way.

This paper describes how ARIFS tool (Approximate Retrieval of Incomplete and Formal Specifications) provides a suitable reusing environment to classify, retrieve and adapt formal and incomplete requirements specifications. Both classification and retrieval tasks are based on functional similarities according to structural and semantic closeness. To this effect, we define four partial orderings among reusable components and different measures to quantify functional differences among them. By using these measures we are able to offer an approximate and efficient retrieval, without formal proofs, and to predict adaptation efforts to satisfy the required functional specification. This paper focus on semantic similarities as they are more remarkable in vertical reuse, that is, the reuse of software within same domain or application area.

The development of requirements specifications can be supported by a cycle composed of two phases: analysis and revision. We use the SCTL-MUS methodology to bridge the gap between these two phases. The analysis phase provides diagnostic information if a desirable property is not satisfied by the current system specification. A crucial aspect of the analysis-revision cycle is how to use the diagnostic information provided to generate alternative system refinements which can be included in the system specification to satisfy the property in question (revision phase). Our approach allows translating the diagnostic information into system requirements refinements closed to the system domain. It facilitates to the stakeholders the decision of what system requirements refinements must be included in the system requirements specification.

The possibility of verifying systems during any phase of the software development process is one of the most significant advantages of using formal methods. Model checking is considered to be the broadest-used formal verification technique, even though a great quantity of computing resources are needed to verify medium-large and large systems. As verification is present over the whole software process, this amount of resources is more critical in incremental and iterative life-cycles. Our proposal focuses on reusing incomplete models and their verification results - which are obtained from a model-checking algorithm - in order to improve this kind of life-cycle. Making good use of these previous verification results can reduce the formal verification costs by minimizing the set of requirements and the set of system states where the properties must be verified. The unspecification that is inherent to incomplete systems is used to provide an approximate and content-oriented retrieval which is supplemented by suggestions to match the desired specifications.

Abstract. This paper introduces an iterative model for the software development process of distributed systems. It is based on dealing with the system evolution and maintenance activities as similar stages of the system development. In order to formalise this model, a multi-valued causal temporal logic, referred to as Simple Causal Temporal Logic (SCTL), is defined for the acquisition and specification of the functional requirements. A Model of Unspecified States (MUS) is also defined with a double goal: firstly, to show the fundamental aspects of system behaviour, which has been specified through a set of SCTL requirements; and, secondly, to verify the consistency and completeness of the specified requirements. The combination of SCTL and MUS allows obtaining the specification of the initial architecture of the system formally. Besides, the design decisions are stored with the goal of making the evolution and maintenance tasks easier. The translation between MUS and a constructive formal description technique (LOTOS) is automatic from the definition of architectural operators.