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 and complex services.

Accepted Papers

Below you can find the list of accepted papers. Details on the specific DADS sessions will be provided later.

• Development Support for QoS-Aware Service-Adaptation in Ubiquitous Computing Applications
  Kurt Geihs, Christoph Evers, Roland Reichle, Michael Wagner, and Mohammad U. Khan

  In ubiquitous computing environments services may be discovered and bound dynamically. Adaptive applications may utilize such services to improve their offered functional and nonfunctional properties. Generally, the adaptation decision depends on the quality of service (QoS) of discovered services. The development of such adaptive applications is a complex, challenging task. In this paper, we present a general methodology for facilitating the development of QoS-dependent self-adaptive applications. We present several lessons learned from application case studies using the new approach.

• Transparent Componentisation: High-level (Re)configurable Programming for Evolving Distributed Systems
  Shen Lin, François Taiani, Marin Bertier, Gordon Blair, and Anne-Marie Kermarrec

  Component frameworks and high-level distributed languages have been widely used to develop distributed systems, and provide complementary advantages: Whereas component frameworks foster composability, reusability, and (re)configurability; distributed languages focus on behaviour, simplicity and programmability. In this paper, we argue that both types of approach should be brought together to help develop complex adaptive systems, and we propose an approach to combines both technologies without compromising on any of their benefits. Our approach, termed Transparent Componentisation, automatically maps a high-level distributed specification onto a underlying component framework. It thus allows developers to focus on the programmatic description of a distributed system's behaviour, while retaining the benefits of a component architecture. As a proof of concept, we present WhispersKit, a programming environment for gossip-based distributed systems. Our evaluation shows that WhispersKit successfully retains the simplicity and understandability of high-level distributed language while providing efficient and transparent reconfigurability thanks to its component underpinnings.

• Root-cause Analysis of Performance Anomalies in Web-based Applications
  João Paulo Magalhães and Luis Moura Silva

  The complexity behind current business-critical applications leads many times to performance problems difficult to anticipate and analyze. In our previous work we described a framework for detection of performance anomalies in web-based and component-based applications. It provides low overhead monitoring, correctly distinguishes performance anomalies from common workload variations and also presents initial information for system or application server changes related with an application performance anomaly.
  In this paper we present a framework extension devised to offer root-cause failure analysis for a given performance anomaly. The monitoring module enables application profiling and ANOVA analysis is used to verify if a performance anomaly is due to internal changes within the application (e.g., application updates) or to external changes (e.g., remote services changes, system/application server change). The paper includes some experimental results that show the effectiveness of our approach to pinpoint the root-cause for different types of performance anomalies and remarks its potential to avoid a considerable number of service failures.

• AdaptStream: Towards Achieving Fluidity in Adaptive Stream-Based Systems
  Yu Liu and René Meier

  Stream-based systems are frequently subject to changes in their operational environments due to fluctuations in the available computation and communication resources. Dynamic adaptation is a mechanism to improve the fitness of such systems. However, adaptation can block one or more streams thus inadvertently acting the timeliness properties of streams. This paper describes AdaptStream, an adaptation framework that provides timeliness support for stream-based adaptations. We introduce the concept of fluidity to measure the temporal alignment of stream synchronization during adaptation. We present a scheduling algorithm that calculates the time-bounded schedule of adaptation actions on multiple streams to achieve the fluidity requirement that is traded off against available resources and the smoothness requirement of individual streams.

• Identifying the Provenance of Correlated Anomalies
  Dawood Tariq, Basim Baig, Ashish Gehani, Salman Mahmood, Rashid Tahir, Azeem Aqil, and Fareed Zaffar

  Identifying when anomalous activity is correlated in a distributed system is useful for a range of applications from intrusion detection to tracking quality of service. The more specific the logs, the more precise the analysis they allow. However, collecting detailed logs from across a distributed system can deluge the network fabric. We present an architecture that allows fine-grained auditing on individual hosts, space-efficient representation of anomalous activity that can be centrally correlated, and tracing anomalies back to individual files and processes in the system. A key contribution is the design of an anomaly-provenance bridge that allows opaque digests of anomalies to be mapped back to their associated provenance.

• Robustness of Automotive Applications Using Reflective Computing: Lessons learnt
  Jean-Charles Fabre, Marc-Olivier Killijian, and Francois Taiani

  In this paper, we present our experience and lessons learnt in applying a multi-level reflective approach to the design and implementation of an industrial embedded dependable system. We reflect in particular on the process by which ideal academic results and assumptions may be mapped to a concrete industrial context. More precisely, our reflection is based on our experience in building an adaptive defense software for a multilayer embedded platform in the automotive industry. This defense software provides a safety bag and is based on computational reflection, an advanced architectural mechanism to separate cross-cutting concerns. Our implementation uses the AUTOSAR middleware, the automotive standard for modular embedded software, and relies on software sensors to observe the behavior of the system, executable assertions to check on-line properties, and software actuators to perform recovery actions. This leads to defense software that is uncoupled from the real functional system and can be adjusted and specialized according to the needs of the system integrator.

Poster session

Finally, a poster paper has been accepted:

• An Approach for Providing Dependable Self-Adaptation in Distributed Embedded Systems
  Marc Zeller, Gereon Weiss, Dirk Eilers, and Rudi Knorr

  Modern distributed embedded systems are reaching an extreme complexity which is very hard to master with traditional methods. Particularly the need for these systems to adapt their behavior autonomously at runtime to changing conditions is a demanding challenge. Since most industrial application domains of distributed embedded systems have high demands on reliability and safety, we need a dependable self-adaptation mechanism to apply adaptation successfully in these domains. Therefore, we propose a concept to guarantee the proper system behavior and a mechanism which preserves the predefined functional and non-functional requirements of the system.

Track Program Co-Chairs

Important Dates