Program

The track provides a forum for scientists and engineers in academia and industry to present and discuss their latest research findings on selected topics in dependable and adaptive distributed systems.

Fri, March 28, 10:00-11:40am

• Autonomic Configuration of HyperDex via Analytical Modelling
  Nuno Diegues, Muhammet Orazov, João Paiva, Luís Rodrigues and Paolo Romano

  HyperDex is a recent multi-dimensional key-value store that allows efficient search for objects using their secondary attributes. However, the advantage of supporting complex queries comes at the cost of a complex configuration. In this paper we address the problem of automating the configuration of this sort of novel key-value stores. We first show that a misconfiguration may significantly affect the performance of such systems. We then derive a performance model that provides key insights on the behaviour of HyperDex. Based on this model, we derive a technique to automatically and dynamically select the best HyperDex configuration.

• ACTRESS: Domain-Specific Modeling of Self-Adaptive Software Architectures
  Filip Krikava, Philippe Collet and Robert France

  A common approach to engineering self-adaptive software systems is to use Feedback Control Loops (FCLs). Advances have led to more explicit and safer design of some control architectures, however, there is a need for more integrated and systematic approaches that support end-to-end integration of FCLs into software systems. In this paper, we propose a tooled approach that enables researchers and engineers to design and integrate adaptation mechanisms into software systems through FCLs. It consists of domain-specific modeling language that raises the level of abstraction on which FCLs are defined, making them amenable to automated analysis and implementation code synthesis. The language supports composition, distribution and reflection thereby enabling coordination and composition of multiple distributed FCLs. Its use is facilitated by a modeling environment, ACTRESS, that provides support for modeling, verification and complete code generation. We report on its application to a concrete adaptation case study and also discuss its self-adaptive capabilities and quality attributes.

• Workload-aware table splitting for NoSQL
  Francisco Cruz, Francisco Maia, Rui Oliveira and Ricardo Vilaça

  Massive scale data stores, which exhibit highly desirable scalability and availability properties are becoming pivotal systems in nowadays infrastructures. Scalability achieved by these data stores is anchored on data independence; there is no clear relationship between data, and atomic inter-node operations are not a concern. Such assumption over data allows aggressive data partitioning. In particular, data tables are horizontally partitioned and spread across nodes for load balancing. However, in current versions of these data stores, partitioning is either a manual process or automated but simply based on table size. We argue that size based partitioning does not lead to acceptable load balancing as it ignores data access patterns, namely data hotspots. Moreover, manual data partitioning is cumbersome and typically infeasible in large scale scenarios. In this paper we propose an automated table splitting mechanism that takes into account the system workload. We evaluate such mechanism showing that it simple, non-intrusive and effective.

• Robustness Evaluation of the Rainbow Framework for Self-Adaptation
  Javier Cámara, Rogério de Lemos, Nuno Laranjeiro, Rafael Ventura and Marco Vieira

  Self-adaptive (or autonomic) systems incorporate complex software components that act as controllers of a target system by executing actions through effectors, based on information monitored by probes. Despite the growing importance and criticality of controllers in many application domains, a central concern about them is the diculty in assessing their robustness when architecting self-adaptive systems. In previous work, we proposed an approach for evaluating the robustness of controllers in self-adaptive systems. In this practical experience report, we describe a comprehensive evaluation of the robustness of a particular controller, in our case Rainbow, in the context of two case studies: a benchmark case study that reproduces the typical infrastructure for a news website, and an industrial middleware for monitoring populated networks of devices. The aim of this work is to assess to what extent the use of a different target system has an impact on the robustness of the controller, which has to be customized in different ways, and may need to resort to the activation of dierent features, depending on the particular target system. Our analysis concludes that the customization of Rainbow (the controller) has little impact on its robustness because of the way the controller was designed and built, and this modularization of non-functional requirements is indeed encouraging when architecting self-adaptive systems.

• Improving Adaptiveness of AUTOSAR Embedded Applications
  Hélène Martorell, Jean-Charles Fabre, Matthieu Roy and Régis Valentin

  AUTOSAR (AUTomotive Open System Architecture) is the most recent standard for automotive embedded systems. A major drawback of AUTOSAR lies in its lack of flexibility. Software-wise, ECUs (Electronic Control Unit) are tested, validated and uploaded; these three steps are performed in a monolithic process. Adding adaptability features into the standard is a major challenge in this context, and may result in consequent savings of time and money. On-line adaptation allows the inclusion of new functionalities in an efficient way. In this paper, we first extract relevant features from AUTOSAR for allowing dynamic software updates. Then, we define our approach for performing updates, and provide an evaluation of our approach on a RISC micro controller.

Poster session, Thu, March 27, 11:00am-6:00pm

• Hierarchical Topology Adaptation for Distributed Convergecast Applications
  Sandip Chakraborty, Suchetana Chakraborty, Sushanta Karmakar and Hridoy Dutta

  Sink based spanning tree topologies are effectively used in convergecast applications for efficient packet delivery with minimum forwarding delay, eliminating packet loss or duplicate packet delivery. For tree based convergecast, this paper theoretically shows that there is a trade-off between the topology architecture and the network traffic load. Depending on this trade-off, a hierarchical topology adaptation scheme is proposed for the tree based convergecast to improve overall application performances. The effectiveness of the proposed scheme is analyzed using simulation results.

• An Energy-aware Service Composition Framework for Service-Oriented Wireless Sensor Networks
  Tao Wang

  Unlike the web services which are software-based and supported with adequate resources, service composition in wireless sensor network is affected by the limited power supply, residual memory and computational ability of the heterogeneous sensor node. In this paper, we proposed an energy-aware service composition framework for developing various applications in the service-oriented heterogeneous wireless sensor network. We have exploited two different energy-aware metrics: energy-aware load-balancing and overall energy consumption. With both the metrics, we have formulated the process of energy-aware sensor service composition into a combinatorial optimization problem and proposed an improved discrete particle swarm optimization (IDPSO) algorithm to compute the optimal service route. An extreme perturbation scheme has been employed to break the stagnant state in the IDPSO algorithm, which increases the particles’ searching field and then improves the probability of finding out better solutions. Through simulation of energy-aware service composition, we demonstrate that the performance of the service route given by IDPSO is approximately equal to the best service route searched out by the exhaustive composition algorithm. The experiment results have shown that our proposed method is able to reduce the energy consumption, prolong the lifetime of the sensor network and provide stable service composition for various applications.

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