RoboPlanner: Towards an Autonomous Robotic Action Planning Framework for Industry 4.0

Autonomous robots are being increasingly integrated into manufacturing, supply chain and retail industries due to the twin advantages of improved throughput and adaptivity. In order to handle complex Industry 4.0 tasks, the autonomous robots require robust action plans, that can self-adapt to runtime changes. A further requirement is efficient implementation of knowledge bases, that may be queried during planning and execution. In this paper, we propose RoboPlanner, a framework to generate action plans in autonomous robots. In RoboPlanner, we model the knowledge of world models, robotic capabilities and task templates using knowledge property graphs and graph databases. Design time queries and robotic perception are used to enable intelligent action planning. At runtime, integrity constraints on world model observations are used to update knowledge bases. We demonstrate these solutions on autonomous picker robots deployed in Industry 4.0 warehouses

QoS Composition and Analysis in Reconfigurable Web Services Choreographies

International audienceQuality 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

Timed protocol analysis of interconnected mobile IoT devices

International audienceWith the emergence of the Internet of Things (IoT), application developers can rely on a variety of protocols and Application Programming Interfaces (APIs) to support data exchange between IoT devices. However, this may result in highly heterogeneous IoT interactions in terms of both functional and non-functional semantics. To map between heterogeneous functional semantics, middleware connectors can be utilized to interconnect IoT devices via bridging mechanisms. In this paper, we make use of the Data eXchange (DeX) connector model that enables interoperability among heterogeneous IoT devices. DeX interactions, including synchronous, asynchronous and streaming, rely on generic post and get primitives to represent IoT device behaviors with varying space/time coupling. Nevertheless, non-functional time semantics of IoT interactions such as data availability/validity, intermittent connectivity and application processing time, can severely affect response times and success rates of DeX interactions. We introduce timing parameters for time semantics to enhance the DeX API. The new DeX API enables the mapping of both functional and time semantics of DeX interactions. By precisely studying these timing parameters using timed automata models, we verify conditions for successful interactions with DeX connectors. Furthermore, we statistically analyze through simulations the effect of varying timing parameters to ensure higher probabilities of successful interactions. Simulation experiments are compared with experiments run on the DeX Mediators (DeXM) framework to evaluate the accuracy of the results. This work can provide application developers with precise design time information when setting these timing parameters in order to ensure accurate runtime behavior

Evaluating the Ease of Application Development for the Internet of Things

The Internet of Things (IoT) combines Wireless Sensor and Actuator Network (WSAN) (the challenge of large scale of systems), pervasive computing (the challenge of heterogeneity of nodes and the user's own interaction with these nodes), and the elements of the "traditional" Internet such as web and database servers. An important challenge in such a diverse and multidisciplinary field is the ease of application development for the stakeholders, who are involved in the IoT application development process. Several application development approaches have been proposed to address this challenge in the related field of WSANs and pervasive computing. However, very few approaches for IoT applications have evaluated their programming framework on factors such as expressiveness and development effort. The former guides the stakeholders to identify a suitable approach for given application requirements at hand. The latter helps the stakeholders the lines of code that need to be written to develop the IoT application, which involves large number of heterogeneous devices. In this paper, we evaluate our previously proposed model-driven approach, which supports the development of IoT applications, on two factors: expressiveness and development effort. The results of the expressiveness clearly indicate the subset of IoT application characteristics that can be suitably developed in our framework. Our evaluation results of the development effort show that (1) our approach drastically reduce development effort for developing IoT applications compared to node-level programming. (2) the reusability of specification and implementation across the same application domain, thus reducing development effort

Queueing Network Modeling Patterns for Reliable and Unreliable Publish/Subscribe Protocols

International audienceMobile Internet of Things (IoT) applications are typically deployed on resource-constrained devices with intermittent network connectivity. To support the deployment of such applications, the Publish/Subscribe (pub/sub) interaction paradigm is often employed, as it decouples mobile peers in time and space. Furthermore, pub/sub middleware protocols and APIs consider the Things' hardware limitations and support the development of effective applications by providing Quality of Service (QoS) features. These features aim to enable developers to tune an application by switching different levels of response times and delivery success rates. However, the profusion of pub/sub middleware protocols coupled with intermittent network connectivity result in non-trivial application tuning. In this paper, we model the performance of middleware protocols found in IoT, which are classified within the pub/sub interaction paradigm-both reliable and unreliable underlying network layers are considered. We model reliable and unreliable protocols, by considering QoS semantics for data validity, buffer capacities as well as the intermittent availability of peers. Finally, we perform statistical analysis by varying these QoS semantics, demonstrating their significant effect on the rate of successful interactions. We showcase the application of our analysis in concrete scenarios relating to Traffic Information Management systems, that integrate both reliable and unreliable participants. The consequent PerfMP performance modeling pattern may be tailored for a variety of deployments, in order to control fine-grained QoS policies

Timeliness Evaluation of Intermittent Mobile Connectivity over Pub/Sub Systems

International audienceSystems deployed in mobile environments are typically characterized by intermittent connectivity and asynchronous sending/reception of data. To create effective mobile systems for such environments, it is essential to guarantee acceptable levels of timeliness between sending and receiving mobile users. In order to provide QoS guarantees in different application scenarios and contexts, it is necessary to model the system performance by incorporating the intermittent connectivity. Queueing Network Models (QNMs) offer a simple modeling environment, which can be used to represent various application scenarios, and provide accurate analytical solutions for performance metrics, such as system response time. In this paper, we provide an analytical solution regarding the end-to-end response time between users sending and receiving data by modeling the intermittent connectivity of mobile users with QNMs. We utilize the publish/subscribe (pub/sub) middleware as the underlying communication infrastructure for the mobile users. To represent the user's connections/disconnections, we model and solve analytically an ON/OFF queueing system by applying a mean value approach. Finally, we validate our model using simulations with real-world workload traces. The deviations between the performance results foreseen by the analytical model and the ones provided by the simulator are shown to be less than 5% for a variety of scenarios

Analysis of Timing Constraints in Heterogeneous Middleware Interactions

International audienceWith the emergence of Future Internet applications that connect web services, sensor-actuator networks and service feeds, scalability and heterogeneity support of interaction paradigms are of critical importance. Heterogeneous interactions can be abstractly represented by client-service, publish-subscribe and tuple space middleware connectors that are interconnected via bridging mechanisms providing interoperability among the services. In this paper, we make use of the eXtensible Service Bus (XSB), proposed in the CHOReOS project as the connector enabling interoperability among heterogeneous choreography participants. XSB models transactions among peers through generic post and get operations that represent peer behavior with varying time/space coupling. Nevertheless, the heterogeneous lease and timeout constraints of these operations severely affect latency and success rates of transactions. By precisely studying the related timing thresholds using timed automata models, we verify conditions for successful transactions with XSB connectors. Furthermore, we statistically analyze through simulations, the effect of varying lease and timeout periods to ensure higher probabilities of successful transactions. Simulation experiments are compared with experiments run on the XSB implementation testbed to evaluate the accuracy of results. This work can provide application developers with precise design time information when setting these timing thresholds in order to ensure accurate runtime behavior

Variability Modeling and QoS Analysis of Web Services Orchestrations

International audienceThe ever-growing choice in diverse services is making service orchestration variability an essential aspect of a composite web service. Influence of this variation on the Quality of Service (QoS) of a composite service is critical and the focus of our work. In this paper, we present a methodology to first model orchestration variability using a feature diagram (FD). The FD specifies a product line of orchestrations represented as configurations of invoked/rejected atomic services. Second, due to the potentially large set of configurations we employ combinatorial testing techniques to automatically generate configurations covering all valid pairwise interactions between services. Third, we analyze QoS variation for each configuration using probabilistic models of QoS. Using a crisis management system case study we experimentally show that pairwise generation covers all QoS outliers and eliminates analysis of > 75\% of all possible configurations. The QoS analysis of the pairwise configurations reveals unsafe/ineffective configurations, helps determine realistic Service Level Agreements (SLAs), and provides valuable feedback to help remodel an orchestration. , bdsk-url-1 = http://www.irisa.fr/triskell/publis/2010/Kattepur2010.pd

Gestion Flexible de la Qualité de Service dans les Orchestrations de Services Web

Web Services are software applications that have heterogeneous implementations, whose interfaces and bindings are capable of being defined, described and discovered over a network. An orchestration of such web services provides a centralized control flow for composite services, that can invoke other services using a series of constructs (sequential, parallel, with timeouts for instance). The focus of this thesis is to study the effect of Quality of Service (QoS) metrics in the performance and contractual obligations of such orchestrations. Firstly, we generate an accurate model to study probabilistic multi-dimensional QoS in web services. When data dependency is involved in orchestrations, conditions to ensure monotonicity are necessary and are incorporated. A rich algebra is presented that can handle multiple dimensions of QoS and provide probabilistic contract composition. A consequence of this is ''weaving'' QoS metrics into functional specifications of orchestrations, that can provide other interesting features such as the causal history of an orchestration control flow. Secondly, we study the effects of such models of QoS on improved Service Level Agreement (SLA) management. From incorporating product line variability and mathematical packages for decision making, to superior simulation techniques to quantify contracts and improved negotiation protocols: these are the applications of the QoS management framework. Some of these techniques are implemented over Orc, a concurrent programming language with constructs to handle multiple features of orchestration specifications.Les services Web sont des applications logicielles avec des implémentations hétérogènes, dont les interfaces et les incarnations peuvent être définis, décrits et découverts sur un réseau. Une orchestration de tels services Web fournit un flux de contrôle centralisé pour les services composites, qui peuvent invoquer d'autres services en utilisant une série de constructions (séquentielle, parallèle, avec des timeouts par exemple). L'objectif de cette thèse est d'étudier l'effet des paramètres de Qualité de Service (QoS) dans la performance et les obligations contractuelles de ces orchestrations. Tout d'abord, nous générons un modèle précis pour étudier la QoS probabiliste multi-dimensionnelle dans les services Web. Lorsque la dépendance des données est présente dans les orchestrations, les conditions pour assurer la monotonie sont nécessaires et sont intégrées. Nous présentons une algèbre riche pouvant gérer plusieurs dimensions de la QoS et fournir une composition de contrat probabiliste. Une conséquence de cela est l'entrelacement des paramètres de QoS en spécifications fonctionnelles des orchestrations, qui peut fournir d'autres fonctionnalités intéressantes comme l'ordonnancement causal d'un flux de contrôle d'orchestration. Ensuite, nous étudions les effets de ces modèles de QoS sur la gestion améliorée des SLAs (Service Level Agreement). Les applications de cette architecture de gestion de la QoS sont diverses et comprennent la prise en compte de la variabilité au sein de la gamme de produits, des progiciels mathématiques pour la prise de décision, des techniques de simulation avancées pour quantifier les contrats et des protocoles de négociation améliorés. Certaines de ces techniques sont implémentées au dessus d'Orc, un langage de programmation concurrente ayant des constructions pour gérer plusieurs aspects de spécifications d'orchestration