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We formulate and study a broadcast problem arising in multi-channel duty cycling wireless body area networks (WBANs), where the sink needs to broadcast the control message to all sensor nodes. The objective is to design robust multichannel wake-up schedule with minimum worst-case broadcast delay while guaranteeing the full broadcast diversity regardless of clock drifts and asymmetric duty cycles. To that end, we first derive the lower-bound of worst-case broadcast delay with full diversity of any broadcast protocol and then design a multichannel broadcast protocol (MCB) that satisfies the performance requirement for the latency and diversity. Finally, the simulation results demonstrate the capability of MCB of ensuring successful broadcast delivery on every channel within the theoretical worst-case broadcast delay, even under asymmetric duty cycles and any amount of clock drifts.

The goal of this roadmap paper is to summarize the state-of-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 onSoftware Engineering for Self-Adaptive Systems,which took place in October 2010.

Supporting the execution of service-oriented applications over ubiquitous networks specifically calls for a service-oriented middleware (SOM), which effectively enables ubiquitous networking while benefiting from the diversity and richness of the networking infrastructure. However, developing ubiquitous applications that exploit the specific features offered by a SOM might be a time-consuming task, which demands a deep knowledge spanning from the application domain concepts down to the underlying middleware technicalities. In this paper, first we present the model-driven development process underpinning ubiSOAP, a SOM for the ubiquitous networking domain. Then, based on the domain concepts defined by the conceptual model of ubiSOAP, its architecture and its technicalities, we propose a domain-specific environment, called ubiDSE, that aids the development of applications that exploits the ubiSOAP features, from design to implementation. ubiDSE allows developers to focus on the main behavior of the modeled systems, rather than on complex details inherent to ubiquitous environments. As part of ubiDSE, specific tools are provided to automatically generate skeleton code for service-oriented applications to be executed on ubiSOAP-enabled devices, hence facilitating the exploitation of ubiSOAP by developers.

International audience; Ambient computing requires the integration of multiple mobile heterogeneous networks. Multi-path communication, in such scenarios, can provide reliability and privacy benefits. Even though the properties of multi-path routing have been already extensively studied and a number of algorithms have been proposed, implementation of such techniques can be tricky, particularly when resource-constrained nodes are connected to each other through hybrid networks with different characteristics. In this paper we discuss the challenges involved in implementing multi-path communication on a middleware for hybrid mobile ad hoc networks. We present the PLASTIC middleware, some compelling applications of multi-path communication and the main issues concerning their implementation as a middleware-provided communication primitive.

International audience; The massive deployment of mobile networks together with the emergence of powerful portable devices has given rise to pervasive computing environments. In such environments, mobile users may discover and access services offered in surrounding networks using Service Discovery Protocols (SDPs). However, several SDPs are currently in use, each one designed for a specific target network architecture and setting. As a result, in today's multi-radio networking environment, SDPs do not equally suit each radio interface. In order to provide effective service discovery in multi-radio networks, the most resource-efficient radio interface should be chosen with respect to two main criteria: the adequacy of the interface against the SDP to be used, and energy saving, which is crucial for battery-powered devices. Toward this goal, this article assesses how to effectively take advantage of the multiple radio interfaces now embedded within wireless devices with respect to energy consumption, from the standpoint of service discovery and access. It further investigates the adequacy of legacy SDPs with the various networks, so as to classify the most appropriate networks for each SDP. Exploitation of these results is finally investigated with the description of an energy-efficient algorithm for SDP-based context sensing in a multi-radio pervasive environment.

International audience; Separation of concerns or aspects is a way to deal with the increasing complexity of systems. The separate design of models for different aspects also promotes a better reusability level. However, an important issue is then to define means to integrate them into a global model. We present a formal and tool-equipped approach for the integration of dynamic models (behaviors expressed using state diagrams) and static models (formal data types) with the benefit to share advantages of both: graphical user-friendly models for behaviors, formal and abstract models for data types. Integration is achieved in a generic way so that it can deal with both different static specification languages (algebraic specifications, Z, B) and different dynamic specification semantics

International audience; —Software cohesion concerns the degree to which the elements of a module belong together. Cohesive software is easier to understand, test and maintain. In the context of service-oriented development, cohesion refers to the degree to which the operations of a service interface belong together. In the state of the art, software cohesion is improved based on refactoring methods that rely on information, extracted from the software implementation. This is a main limitation towards using these methods in the case of Web services: Web services do not expose their implementation; instead all that they export is the Web service interface specification. To deal with this problem, we propose an approach that enables the cohesion-driven decomposition of service interfaces, without information on how the services are implemented. Our approach progressive decomposes a given service interface into more cohesive interfaces; the backbone of the approach is a suite of cohesion metrics that rely on information, extracted solely from the specification of the service interface. We validate the approach in 22 real-world services, provided by Amazon and Yahoo. We assess the effectiveness of the proposed approach, concerning the cohesion improvement, and the number of interfaces that result from the decomposition of the examined interfaces. Moreover, we show the usefulness of the approach in a user study, where developers assessed the quality of the produced interfaces.

International audience; In this paper, we discuss how for self-adaptive systems some activities that traditionally occur at development-time are moved to run-time. Responsibilities for these activities shift from software engineers to the system itself, causing the traditional boundary between development-time and run-time to blur. As a consequence, we argue how the traditional software engineering process needs to be reconceptualized to distinguish both development-time and run-time activities, and to support designers in taking decisions on how to properly engineer such systems. Furthermore, we identify a number of challenges related to this required reconceptualization, and we propose initial ideas based on process modeling. We use the Software and Systems Process Engineering Meta-Model (SPEM) to specify which activities are meant to be performed off-line and on-line, and also the dependencies between them. The proposed models should capture information about the costs and benefits of shifting activities to run-time, since such models should support software engineers in their decisions when they are engineering self-adaptive systems.

International audience; The essential issue of interoperability in distributed systems is becoming even more pressing in the Future Internet, where complex applications will be composed from extremely heterogeneous systems. Open system integration paradigms, such as service oriented architecture (SOA) and enterprise service bus (ESB), have provided answers to the interoperability requirement. However, when it comes to integrating systems featuring heterogeneous interaction paradigms, such as client-service, publish-subscribe and tuple space, existing solutions are typically ad hoc and partial, applying to specific interaction protocol technologies. In this paper, we introduce an interoperability solution based on abstraction and merging of the common high-level semantics of interaction paradigms, which is sufficiently general and extensible to accommodate many different protocol technologies. We apply this solution to revisit the SOA- and ESB-based integration of heterogeneous distributed systems.

International audience; The sensor networking field is evolving into the Internet of Things~(IoT), owing in large part to the increased availability of consumer sensing devices, including modern smart phones. However, application development in the IoT still remains challenging, since it involves dealing with several related issues, such as lack of proper identification of roles of various stakeholders, as well as lack of suitable (high-level) abstractions to address the large scale and heterogeneity in IoT systems. Although the software engineering community has proposed several approaches to address the above in the general case, existing approaches for IoT application development only cover limited subsets of above mentioned challenges. In this paper, we propose a multi-stage model-driven approach for IoT application development based on a precise definition of the role to be played by each stakeholder involved in the process -- domain expert, application designer, application developer, device developer, and network manager. The abstractions provided to each stakeholder are further customized using the inputs provided in the earlier stages by other stakeholders. We have also implemented code-generation and task-mapping techniques to support our approach. Our initial evaluation based on two realistic scenarios shows that the use of our techniques/framework succeeds in improving productivity in the IoT application development process.

International audience; Quality of Service (QoS) in orchestrated web services compositions have been well studied with probabilistic and multi-dimensional models. Choreographies that involve message passing among services, on the other hand, require further analysis. In this paper, we begin with the set of QoS domains that may be studied in case of choreographies and the algebraic rules for their composition. As choreographies manage QoS composition in a distributed fashion, techniques to enrich functional specifications with QoS are examined using the model proposed in the CHOReOS project. These are further analyzed with choreographies that may reconfigure due to functional or QoS requirements. Studies on the effects of such reconfiguration on multiple QoS domains can lead to better understanding of optimal runtime configurations along with associated tradeoffs. A goal programming approach is also proposed to choose Pareto optimal solutions with respect to diverse QoS domains.

International audience; In recent years, there has been a growing interest towards the application of artificial intelligence approaches in software engineering (SE) processes. In the specific area of SE for self-adaptive systems (SASs) there is a growing research awareness about the synergy between SE and AI. However, just few significant results have been published. This paper briefly studies uncertainty in SASs and surveys techniques that have been developed to engineer SASs in order to tackle uncertainty. In particular, we highlight techniques that use AI concepts. We also report and discuss our own experience using Dynamic Decision Networks (DDNs) to model and support decision-making in SASs while explicitly taking into account uncertainty. We think that Bayesian inference, and specifically DDNs, provide a useful formalism to engineer systems that dynamically adapt themselves at runtime as more information about the environment and the execution context is discovered during execution. We also discuss partial results, challenges and future research avenues.

International audience; Bayesian decision theory is increasingly applied to support decision-making processes under environmental variability and uncertainty. Researchers from application areas like psychology and biomedicine have applied these techniques successfully. However, in the area of software engineering and specifically in the area of self-adaptive systems (SASs), little progress has been made in the application of Bayesian decision theory. We believe that techniques based on Bayesian Networks (BNs) are useful for systems that dynamically adapt themselves at runtime to a changing environment, which is usually uncertain. In this paper, we discuss the case for the use of BNs, specifically Dynamic Decision Networks (DDNs), to support the decision-making of self-adaptive systems. We present how such a probabilistic model can be used to support the decision-making in SASs and justify its applicability. We have applied our DDN-based approach to the case of an adaptive remote data mirroring system. We discuss results, implications and potential benefits of the DDN to enhance the development and operation of self-adaptive systems, by providing mechanisms to cope with uncertainty and automatically make the best decision.

International audience; Different modeling techniques have been used to model requirements and decision-making of self-adaptive systems (SASs). Specifically, goal models have been prolific in supporting decision-making depending on partial and total fulfilment of functional (goals) and non-functional requirements (softgoals). Different goalrealization strategies can have different effects on softgoals which are specified with weighted contribution-links. The final decision about what strategy to use is based, among other reasons, on a utility function that takes into account the weighted sum of the different effects on softgoals. [Questions/Problems] One of the main challenges about decisionmaking in self-adaptive systems is to deal with uncertainty during runtime. New techniques are needed to systematically revise the current model when empirical evidence becomes available from the deployment. [Principal ideas/results] In this paper we enrich the decision-making supported by goal models by using Dynamic Decision Networks (DDNs). Goal realization strategies and their impact on softgoals have a correspondence with decision alternatives and conditional probabilities and expected utilities in the DDNs respectively. Our novel approach allows the specification of preferences over the softgoals and supports reasoning about partial satisfaction of softgoals using probabilities. We report results of the application of the approach on two different cases. Our early results suggest the decision-making process of SASs can be improved by using DDNs.

International audience; One of the main benefits of mobile participatory sensing becoming a reality is the increased knowledge it will provide about the real world, as it is expected to rely on a large number of smart and mobile devices. Nowadays, those devices have the ability to host different types of sensors that will be incorporated in every aspect of our daily lives. However, given the constantly increasing number of capable mobile devices, any participatory sensing approach should be, first and foremost, scalable. To address this challenge, we present an approach to decrease the participation of devices (in sensing tasks) in a manner that does not compromise the accuracy of the real-world information while increasing the efficiency of the overall system. To reduce the number of the devices involved, we present a probabilistic registration approach enabling only a subset of devices to register their services while still providing adequate coverage of the deployment area. Our techniques, based on a re- alistic human mobility model, allow devices to decide whether or not to register their sensing services depending on the probability of other, equivalent devices being present at the locations of their expected path. We present the design and implementation of a registration middleware based on our techniques, using which mobile devices can base their registration decision. Through experiments performed on real and simulated datasets, we show that our approach scales, while not sacrificing significant amounts of sensing coverage.

International audience; Software systems are increasingly composed of independently developed heterogeneous components. To ensure interoperability, mediators are needed that coordinate actions and translate exchanged messages between the components. We present a technique for automated synthesis of mediators, by means of a quotient operator, that is based on behavioural models of the components and an ontological model of the data domain. By not requiring a specification of the composed system, the method supports both off-line and run-time synthesis. The obtained mediator is the most general component that ensures freedom of both communication mismatches and deadlock in the composition. Validation of the approach is given by implementation of a prototype tool, while applicability is illustrated on heterogeneous holiday booking components.

Software systems are increasingly composed of independently-developed components, which are often systems by their own. This composition is possible only if the components are interoperable, i.e., are able to work together in order to achieve some user tasks. However, interoperability is often hampered by the differences in the data types, communication protocols, and middleware technologies used by the components involved. In order to enable components to interoperate despite these differences, mediators that perform the necessary data translations and coordinate the components' behaviours appropriately, have been introduced. Still, interoperability remains a critical challenge for today's and even more tomorrow's distributed systems that are highly heterogeneous and dynamic. This chapter introduces the fundamental principles and solutions underlaying interoperability in software systems with a special focus on protocols. First, we take a software architecture perspective and present the fundamentals for reasoning about interoperability and bring out mediators as a key solution to achieve protocol interoperability. Then, we review the solutions proposed for the implementation, synthesis, and dynamic deployment of mediators. We show how these solutions still fall short in automatically solving the interoperability problem in the context of systems of systems. This leads us to present the solution elaborated in the context of the European Connect project, which revolves around the notion of emergent middleware, whereby mediators are synthesised on the fly. We consider the GMES Global Monitoring of Environment and Security initiative and use it to illustrate the different solutions presented.

International audience; Self-adaptation is emerging as an increasingly important capability for many applications, particularly those deployed in dynamically changing environments, such as ecosystem monitoring and disaster management. One key challenge posed by Self-Adaptive Systems (SAS) is the need to handle changes to the requirements and corresponding behavior of a SAS in response to varying environmental condition during runtime. In this paper, we discuss the role of uncertainty in such systems, research challenges and present results from our experiences when tackling those challenges. We also review di erent modeling techniques for the development of self-adaptive systems with speci c emphasis on goal-based techniques.

International audience; he success of pervasive computing depends on the ability to compose a multitude of networked applications dynamically in order to achieve user goals. However, applications from different providers are not able to interoperate due to incompatible interaction protocols or disparate data models. Instant messaging is a representative example of the current situation, where various competing applications keep emerging. To enforce interoperability at runtime and in a non-intrusive manner, mediators are used to perform the necessary translations and coordination between the heterogeneous applications. Nevertheless, the design of mediators requires considerable knowledge about each application as well as a substantial development effort. In this paper we present an approach based on ontology reasoning and model checking in order to generate correct-by-construction mediators automatically. We demonstrate the feasibility of our approach through a prototype tool and show that it synthesises mediators that achieve efficient interoperation of instant messaging applications.

International audience; Models at runtime can be defined as abstract representations of a system, including its structure and behaviour, which exist in tandem with the given system during the actual execution time of that system. Furthermore, these models should be causally connected to the system being modelled, offering a reflective capability. Significant advances have been made in recent years in applying this concept, most notably in adaptive systems. In this paper we argue that a similar approach can also be used to support the dynamic generation of software artefacts at execution time. An important area where this is relevant is the generation of software mediators to tackle the crucial problem of interoperability in distributed systems. We refer to this approach as emergent middleware, representing a fundamentally new approach to resolving interoperability problems in the complex distributed systems of today. In this context, the runtime models are used to capture meta-information about the underlying networked systems that need to interoperate, including their interfaces and additional knowledge about their associated behaviour. This is supplemented by ontological information to enable semantic reasoning. This paper focuses on this novel use of models at runtime, examining in detail the nature of such runtime models coupled with consideration of the supportive algorithms and tools that extract this knowledge and use it to synthesise the appropriate emergent middleware.

International audience; A self-adaptive system adjusts its configuration to tolerate changes in its operating environment. To date, requirements modeling methodologies for self-adaptive systems have necessitated analysis of all potential system configurations, and the circumstances under which each is to be adopted. We argue that, by explicitly capturing and modelling uncertainty in the operating environment, and by verifying and analysing this model at runtime, it is possible for a system to adapt to tolerate some conditions that were not fully considered at design time. We showcase in this paper our tools and research results.

Requirements-aware systems address the need to reason about uncertainty at runtime to support adaptation decisions, by representing quality of services (QoS) requirements for service-based systems (SBS) with precise values in run-time queryable model specification. However, current approaches do not support updating of the specification to reflect changes in the service market, like newly available services or improved QoS of existing ones. Thus, even if the specification models reflect design-time acceptable requirements they may become obsolete and miss opportunities for system improvement by self-adaptation. This articles proposes to distinguish "abstract" and "concrete" specification models: the former consists of linguistic variables (e.g. "fast") agreed upon at design time, and the latter consists of precise numeric values (e.g. "2ms") that are dynamically calculated at run-time, thus incorporating up-to-date QoS information. If and when freshly calculated concrete specifications are not satisfied anymore by the current service configuration, an adaptation is triggered. The approach was validated using four simulated SBS that use services from a previously published, real-world dataset; in all cases, the system was able to detect unsatisfied requirements at run-time and trigger suitable adaptations. Ongoing work focuses on policies to determine recalculation of specifications. This approach will allow engineers to build SBS that can be protected against market-caused obsolescence of their requirements specifications.

As a subset of the Internet of Things (IoT), the Web of Things (WoT) shares many characteristics with wireless sensor and actuator networks (WSANs) and ubiquitous computing systems (Ubicomp). Yet to a far greater degree than the IoT, WSANs or Ubicomp, the WoT will integrate physical and information objects, necessitating a means to model and reason about a range of context types that have hitherto received little or no attention from the RE community. RE practice is only now developing the means to support WSANs and Ubicomp system development, including faltering first steps in the representation of context. We argue that these techniques will need to be developed further, with a particular focus on rich context types, if RE is to support WoT application development.

International audience; The Future Internet environments raise challenging issues for the Service-Oriented Architectures. Due to the scalability and heterogeneity issues new approaches are thought in order to leverage the SOA to support a wider range of services and users. The CHOReOS project is part of the European Community Initiative to sketch technological solutions for the future ultra large systems. In particular, CHOReOS explores the choreography of services paradigm. Within this project, a conceptual architecture combining both the development and runtime environments is realized. This chapter introduces the CHOReOS Integrated Development and Runtime Environment, aka IDRE.

International audience; The computing and networking capacities of today's wireless portable devices allow for ubiquitous services, which are seamlessly networked. Indeed, wireless handheld devices now embed the necessary resources to act as both service clients and providers. However, the ubiquitous networking of services remains challenged by the inherent mobility and resource constraints of the devices, which make services a priori highly volatile. This paper discusses the design, implementation and experimentation of the ubiSOAP service-oriented middleware, which leverages wireless networking capacities to effectively enable the ubiquitous networking of services. ubiSOAP specifically defines a layered communication middleware that underlies standard SOAP-based middleware, hence supporting legacy Web Services while exploiting nowadays ubiquitous connectivity.

Diversity is prevalent in modern software systems to facilitate adapting the software to customer requirements or the execution environment. Diversity has an impact on all phases of the software development process. Appropriate means and organizational structures are required to deal with the additional complexity introduced by software variability. This introductory article to the special section “Software Diversity—Modeling, Analysis and Evolution” provides an overview of the current state of the art in diverse systems development and discusses challenges and potential solutions. The article covers requirements analysis, design, implementation, verification and validation, maintenance and evolution as well as organizational aspects. It also provides an overview of the articles which are part of this special section and addresses particular issues of diverse systems development. Comisión Interministerial de Ciencia y Tecnología TIN2009-07366 Junta de Andalucía TIC-5906 Junta de Andalucía P07-TIC-2533

Service-based systems are applications built by composing pre-existing services. During design time and according to the specifications, a set of services is selected. Both, service providers and consumers exist in a service market that is constantly changing. Service providers continuously change their quality of services (QoS), and service consumers can update their specifications according to what the market is offering. Therefore, during runtime, the services are periodically and manually checked to verify if they still satisfy the specifications. Unfortunately, humans are overwhelmed with the degree of changes exhibited by the service market. Consequently, verification of the compliance specification and execution of the corresponding adaptations when deviations are detected cannot be carried out in a manual fashion. In this work, we propose a framework to enable online awareness of changes in the service market in both consumers and providers by representing them as active software agents. At runtime, consumer agents concretize QoS specifications according to the available market knowledge. Services agents are collectively aware of themselves and of the consumers' requests. Moreover, they can create and maintain virtual organizations to react actively to demands that come from the market. In this paper we show preliminary results that allow us to conclude that the creation and adaptation of service-based systems can be carried out by a self-organized service market system.

Part 8: Run-Time (Re)configuration and Inspection; International audience; Interoperability is a fundamental problem in distributed systems, and an increasingly difficult problem given the level of heterogeneity and dynamism exhibited by contemporary systems. While progress has been made, we argue that complexity is now at a level such that existing approaches are inadequate and that a major re-think is required to identify principles and associated techniques to achieve this central property of distributed systems. In this paper, we postulate that emergent middleware is the right way forward; emergent middleware is a dynamically generated distributed system infrastructure for the current operating environment and context. In particular, we focus on the key role of ontologies in supporting this process and in providing underlying meaning and associated reasoning capabilities to allow the right run-time choices to be made. The paper presents the CONNECT middleware architecture as an example of emergent middleware and highlights the role of ontologies as a cross-cutting concern throughout this architecture. Two experiments are described as initial evidence of the potential role of ontologies in middleware. Important remaining challenges are also documented.

International audience; Challenges the Internet of Things (IoT) is facing are directly inherited from today's Internet. However, they are amplified by the anticipated large scale deployments of devices and ser- vices, information flow and involved users in the IoT. Chal- lenges are many and we focus on addressing those related to scalability, heterogeneity of IoT components, and the highly dynamic and unknown nature of the network topology. In this paper, we give an overview of a service-oriented middle- ware solution that addresses those challenges using semantic technologies to provide interoperability and flexibility. We especially focus on modeling a set of ontologies that describe devices and their functionalities and thoroughly model the domain of physics. The physics domain is indeed at the core of the IoT, as it allows the approximation and estimation of functionalities usually provided by things. Those function- alities will be deployed as services on appropriate devices through our middleware.

Part 5: Notification and Streaming; International audience; Multimedia streaming when smartphones act as both clients and servers is difficult. Indeed, multimedia streaming protocols and associated data formats supported by today's smartphones are highly heterogeneous. At the same time, multimedia processing is resource consuming while smartphones are resource-constrained devices. To overcome this complexity, we present AmbiStream, a lightweight middleware layer solution, which enables applications that run on smartphones to easily handle multimedia streams. Contrarily to existing multimedia-oriented middleware that propose a complete stack for multimedia streaming, our solution leverages the available highly-optimized multimedia software stack of the smartphones' platforms and complements them with additional, yet resource-efficient, layers to enable interoperability. We introduce the challenges, present our approach and discuss the experimental results obtained when executing AmbiStream on both Android and iOS smartphones. Our results show that it is possible to perform adaptation at run time and still obtain streams with satisfactory quality.

ISBN: 978-1-4503-1072-7; International audience; The Internet of Things (IoT) integrates the physical world with the existing Internet, and is rapidly gaining popularity, thanks to the increased adoption of smart phones and sensing devices. One of the important challenges in this domain is to enable domain experts to easily specify applications for the IoT. As a first step towards developing a suitable programming abstraction, in this paper we present a domain model for applications in the Internet of Things, based on a survey of recently proposed IoT applications from the real world that represent a wide class of behaviors found in IoT use cases.

International audience; In earlier work we proposed the idea of requirements-aware systems that could introspect about the extent to which their goals were being satisfied at runtime. When combined with requirements monitoring and self adaptive capabilities, requirements awareness should help optimize goal satisfaction even in the presence of changing run-time context. In this paper we describe initial progress towards the realization of requirements-aware systems with REAssuRE. REAssuRE focuses on explicit representation of assumptions made at design time. When such assumptions are shown not to hold, REAssuRE can trigger system adaptations to alternative goal realization strategies.

International audience; The modern environment of mobile, pervasive, evolving ser- vices presents a great challenge to traditional solutions for enabling in- teroperability. Automated solutions appear to be the only way to achieve interoperability with the needed level of flexibility and scalability. While necessary, the techniques used to determine compatibility, as a precursor to interaction, come at a substantial computational cost, especially when checks are performed between systems in unrelated domains. To over- come this, we apply machine learning to extract high-level functionality information through text categorisation of a system's interface descrip- tion. This categorisation allows us to restrict the scope of compatibility checks, giving an overall performance gain when conducting matchmak- ing between systems. We have evaluated our approach on a corpus of web service descriptions, where even with moderate categorisation accuracy, a substantial performance benefit can be found. This in turn improves the applicability of our overall approach for achieving interoperability in the Connect project.

A design issue that often appears in real-world services is that their interfaces are not cohesive, i.e., they consist of many and possibly unrelated operations. This issue may complicate the comprehension of the services functionalities and the maintenance of the applications that use them. Currently, the state of the art on case studies that focus on the evaluation of the cohesion of services offered by major service providers is limited, while research efforts on corresponding cohesion metrics are at a quite early stage. In particular, there exist coarse-grained metrics of cohesion lack, which consider that the operations of a service interface are related if the types of certain of their input/output data exactly match. The problem in this approach is that operations which operate on data characterized by similar, but not exactly matching, types are treated as being totally unrelated. Consequently, the aforementioned metrics may overestimate the cohesion lack of service interfaces. In this paper, we undertake a more elaborate approach to evaluate a set of real world services provided by Amazon. Specifically, we propose two fine-grained metrics of cohesion lack, which are defined with respect to the structural similarity of the input/output data types of interface operations. The proposed metrics are formally defined and analytically assessed with respect to fundamental properties of software metrics. Finally we report the results from our case study.

Part 3: Short Papers; International audience; The growing trend to social networking and increased preva- lence of new mobile devices lead to the emergence of mobile social networking applications where users are able to share experience in an impromptu way as they move. However, this is at risk for mobile users since they may not have any knowledge about the users they socially connect with. Trust management then appears as a promising decision support for mobile users in establishing social links. However, while the literature is rich of trust models, most approaches lack appropriate trust bootstrapping, i.e., the initialization of trust values. This paper addresses this challenge by introducing proximity-based trust initialization based on the users' behavioral data available from their mobile devices or other types of social interactions. The proposed approach is further assessed in the context of mobile social networking using users behavioral data collected by the MIT reality mining project. Results show that the inferred trust values correlate with the self-report survey of users relationships.

International audience; The complexity of environments faced by dynamically adap- tive systems (DAS) means that the RE process will often be iterative with analysts revisiting the system speci¯cations based on new environmental understanding product of ex- periences with experimental deployments, or even after ¯nal deployments. An ability to trace backwards to an identi¯ed environmental assumption, and to trace forwards to ¯nd the areas of a DAS's speci¯cation that are a®ected by changes in environmental understanding aids in supporting this nec- essarily iterative RE process. This paper demonstrates how claims can be used as markers for areas of uncertainty in a DAS speci¯cation. The paper demonstrates backward tracing using claims to identify faulty environmental under- standing, and forward tracing to allow generation of new behaviour in the form of policy adaptations and models for transitioning the running system.

International audience; Several lines of research rely on the concept of service abstractions to enable the organization, the composition and the adaptation of services. However, what is still missing, is a systematic approach for extracting service abstractions out of the vast amount of services that are available all over theWeb. To deal with this issue, we propose an approach for mining service abstractions, based on an agglomerative clustering algorithm. Our experimental ndings suggest that the approach is promising and can serve as a basis for future research.

International audience; With the increased prevalence of advanced mobile devices (the so-called \smart" phones), interest has grown in mobile social ecosystems, where users not only access traditional Web-based social networks using their mobile devices, but are also able to use the context information provided by these devices to further enrich their interactions. In complex mobile social ecosystems of the future the heterogeneity of software platforms on constituent nodes, combined with their intrinsic distributed nature and heterogeneity of representation of data and context raises the need for middleware support for the development of mobile social applications. In this paper, we propose Yarta, a novel middleware designed for mobile social ecosystems (MSE), which takes into account the heterogeneity of both deployment nodes and available data, the intrinsic decentralized nature of mobile social applications, as well as users' privacy concerns. To validate our approach, we show how we developed two mobile social applications over Yarta, and report on both its e ciency and ease-of use by way of extensive evaluation on smart phones and laptops.

International audience; Interoperability among heterogeneous systems is a key challenge in today's networked environment, which is characterised by continual change in aspects such as mobility and availability. Automated solutions appear then to be the only way to achieve interoperability with the needed level of flexibility and scalability. While necessary, the techniques used to achieve interaction, working from the highest application level to the lowest protocol level, come at a substantial computational cost, especially when checks are performed indiscriminately between systems in unrelated domains. To overcome this, we propose to use machine learning to extract the high-level functionality of a system and thus restrict the scope of detailed analysis to systems likely to be able to interoperate.

International audience; Networked devices, such as consumer electronics, digital media appliances and mobile devices are rapidly filling our everyday environments and changing them into ubiquitous spaces. Composing an application from resources and services available in these environments is a complex task which requires solving a number of equally important engineering challenges as well as issues related to user behaviour and acceptance. In this chapter we introduce CADEAU, a prototype that addresses these challenges through a unique combination of autonomic mechanisms for application composition and methods for user interaction. These methods differ from each other in the degree to which the user is involved in the control of the prototype. They are offered so that users can choose the appropriate method according to their needs, the application and other context information. These methods use the mobile device as an interaction tool that connects users and resources in the ubiquitous space. We present the architecture, the interaction design and the implementation of CADEAU and give the results of a user study that involved 30 participants from various backgrounds. This study explores the balance between user control and system autonomy depending on different contexts, the user's needs and expertise. In particular, the study analyses the circumstances under which users prefer to rely on certain interaction methods for application composition. We argue that this study is a key step towards better user acceptance of future systems for the composition of ubiquitous applications.

International audience; In randomly deployed visual wireless sensor networks for surveillance applications, the scheduling of sensor nodes can be seen from the risk perspective: different parts of the area of interest may have different risk levels according to the pattern of observed events such as the number of detected intrusions. In this paper, we propose a multiple-level activity model that uses behavior functions to define application classes and allows for adaptive scheduling based on the application criticality and on the availability of multiple cover sets per sensor node. The paper then describes how an adaptive scheduling model can be defined in order to dynamically schedule nodes by varying the capture speed according to nodes' environment. Simulation results are presented to validate the performance of the proposed approach in terms of percentage of active nodes, percentage of coverage and stealth time under intrusion scenarios.

Security and Trust offer two different prospectives on the problem of the correct interaction among software components. For many aspects, they represent complementary viewpoints. Moreover, in the study of the verification of non-functional properties of programs they represent a mainstream. Several security aspects, e.g., access control, could be based also on trust and, vice versa, trust models could update the level of trust of a (component of a ) system according to the satisfaction of a particular security policies. According to that, here we present the Security-by-Contract-with-Trust framework, S×C×T for short. It has been developed considering a system platform that has to execute an application whose developer is unknown in such a way that security policies set on it are not violated. The S×C×T mechanism is driven by both security and trust aspects. It is based of three main concepts: the application code, the application contract, and the system security policy The level of trust we consider measures the adherence of the application code to its contract, i.e., if the code respects its contract then the application is trusted, otherwise its level of trust decreases. According to the level of trust of the application, S×C×T decides if check the contract against the policies and if the answer is positive, execute the application just monitoring its contract, or directly enforce the security policy set on the platform. In order to better describe how the proposed mechanism works, we present its application to a mobile application marketplace scenarios. In this way we are also able to show its possible advantages in terms of performances and modularity.

Part 2: Full Papers; International audience; Computational trust is a central paradigm in today's Internet as our modern society is increasingly relying upon online transactions and social net- works. This is indeed leading to the introduction of various trust management systems and associated trust models, which are customized according to their target applications. However, the heterogeneity of trust models prevents exploiting the trust knowledge acquired in one context in another context although this would be beneficial for the digital, ever-connected environment. This is such an issue that this paper addresses by introducing an approach to achieve interoperability between heterogeneous trust management systems. Specifically, we define a trust meta-model that allows the rigorous specification of trust models as well as their composition. The resulting composite trust models enable heterogeneous trust management systems to interoperate transparently through mediators.

International audience; The Internet of Things plays a central role in the foreseen shift of the Internet to the Future Internet, as it incarnates the drastic expansion of the In- ternet network with non-classical ICT devices. It will further be a major source of evolution of usage, due to the penetration in the user's life. As such, we en- vision that the Internet of Things will cooperate with the Internet of Services to provide users with services that are aware of their surrounding environment. The supporting service-oriented middleware shall then abstract the functionalities of Things as services as well as provide the needed interoperability and flexibil- ity, through a loose coupling of components and composition of services. Still, core functionalities of the middleware, namely service discovery and composi- tion, need to be revisited to meet the challenges posed by the Internet of Things. Challenges in particular relate to the ultra large scale, heterogeneity and dynam- ics of the Internet of Things that are far beyond the ones of today's Internet of Services. In addition, new challenges also arise, pertaining to the physical-world aspect that is central to the IoT. In this paper, we survey the major challenges posed to service-oriented middleware towards sustaining a service-based Internet of Things, together with related state of the art. We then concentrate on the spe- cific solutions that we are investigating within the INRIA ARLES project team as part of the CHOReOS European project, discussing new approaches to overcome the challenges particular to the Internet of Things.

International audience; Activity-oriented computing (AOC) is a paradigm promoting the run-time realization of applications by composing ubiquitous services in the user's surroundings according to abstract specifications of user activities. The paradigm is particularly well-suited for enacting ubiquitous applications. However, there is still a need for end-users to create and control the ubiquitous applications because they are better aware of their own needs and activities than any existing context-aware system could ever be. In this chapter, we give an overview of state of the art ubiquitous application composition, present the architecture of the MEDUSA middleware and demonstrate its realization, which is based on existing open-source solutions. On the basis of our discussion on state of the art ubiquitous application composition, we argue that current implementations of the AOC paradigm are lacking in end-user support. Our solution, the MEDUSA middleware, allows end-users to explicitly compose applications from networked services, while building on an activity-oriented computing infrastructure to dynamically realize the composition.

International audience; This chapter deals with interoperability among pervasive networked systems, in particular accounting for the heterogeneity of protocols from the application down to the middleware layer, which is mandatory for today's and even more for tomorrow's open and highly heterogeneous networks. The chapter then surveys existing approaches to middleware interoperability, further providing a formal specification so as to allow for rigorous characterization and assessment. In general, existing approaches fail to address interoperability required by today's ubiquitous and heterogeneous networking environments where interaction protocols run by networked systems need to be mediated at both application and middleware layers. To meet such a goal, this chapter introduces the approach that is investigated within the Connect project and that deals with the dynamic synthesis of emergent connectors that mediate the interaction protocols executed by the networked systems.

International audience; Distributed systems are becoming more complex in terms of both the level of heterogeneity encountered coupled with a high level of dynamism of such systems. Taken together, this makes it very difficult to achieve the crucial property of interoperability that is enabling two arbitrary systems to work together relying only on their declared service specification. This chapter examines this issue of interoperability in considerable detail, looking initially at the problem space, and in particular the key barriers to interoperability, and then moving on to the solution space, focusing on research in the middleware and semantic interoperability communities. We argue that existing approaches are simply unable to meet the demands of the complex distributed systems of today and that the lack of integration between the work on middleware and semantic interoperability is a clear impediment to progress in this area. We outline a roadmap towards meeting the challenges of interoperability including the need for integration across these two communities, resulting in middleware solutions that are intrinsically based on semantic meaning. We also advocate a dynamic approach to interoperability based on the concept of emergent middleware.

International audience; Current solutions to interoperability remain limited with respect to highly dynamic and heterogeneous environments, where systems encounter one another spontaneously. In this chapter, we introduce the Connect architecture, which puts forward a fundamentally different method to tackle the interoperability problem. The philosophy is to observe networked systems in action, learn their behaviour and then dynamically generate mediator software which will connect two heterogeneous systems. We present a high-level overview of how Connect operates in practice and subsequently provide a simple example to illustrate the architecture in action.

International audience; Owing to the large scale of networked sensor systems, ease of program- ming remains a hurdle in their wide acceptance. High-level application development techniques, or macroprogramming provides an easy to use high-level representation to the application developer, who can focus on specifying the behavior of the system, as opposed to the constituent nodes of the wireless sensor network (WSN). This chapter provides an overview of the current approaches to high-level appli- cation design for WSNs, going into the details related to data-driven macroprogram- ming. Details of one such language are provided, in addition to the approach taken to the compilation of data-driven macroprograms to node-level code. An implemen- tation of the modular compilation framework is also discussed, as well as a graphical toolkit built around it that supports data-driven macroprogramming. Through exper- iments, it is shown that the code generated by the compiler matches hand-generated implementations of the applications, while drastically reducing the time and effort involved in developing real-world WSN applications.

International audience; Interoperability is a key and challenging requirement in today's and future systems, which are often characterized by an extreme level of heterogeneity. To build an interoperability solution between the networked systems populating the environment, both their functional and non-functional requirements have to be met. Because of the continuous evolution of such systems, mechanisms that are fixed a-priori are inadequate to achieve interoperability. In such challenging settings, on-the-fly approaches are best suited. This paper presents, as an interoperability solution, an approach that integrates an automated technique for the synthesis of mediator protocols with a monitoring mechanism. The former aims to provide interoperability taking care of functional characteristics of the networked systems, whereas the latter makes it possible to assess the non-functional characteristics of the connected system.