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. The track is structured in two sessions:

Wed, March 28, 14:10-15:50 (together with 2 papers from the Web Technologies Track

• DRAP: A Robust Authentication Protocol to Ensure Survivability of Computational RFID Networks
  Farzana Rahman and Sheikh Iqbal Ahamed

  The Wireless Identification and Sensing Platform (WISP) from Intel Research Seattle is an instance of Computational RFID (CRFID). CRFID Tag authentication is an evident technique employed by the readers of the WISP networks to prevent various attacks. However, as WISP tags have sensor data along with its ID, the authentication technique of these tags should be different than the ones found in typical RFID networks. Moreover, there can be situation where an adversary may create more collisions at the link layer to initiate the de-synchronization attack. This in turn will result in DoS attack and will increase the system response time. In this paper, we propose a De-synchronization attack resistant Robust Authentication Protocol (DRAP) for WISP networks. Our proposal offers a lightweight solution to defend against the major security attacks including de-synchronization and DoS attacks. This protocol can get back the desynchronized tags and readers to their normal state, and thus provides robustness and ensures survivability. In order to defend these attacks even at the link layer, we also propose EDFSA based communication technique. Finally, to evaluate our protocol, we performed simulation of a WISP network using our proposed experimental model.

• Non-Intrusive Policy Optimization for Dependable and Adaptive Service-Oriented Systems
  Christian Inzinger, Benjamin Satzger, Waldemar Hummer, Philipp Leitner and Schahram Dustdar

  The Service-Oriented Architecture paradigm facilitates the creation of distributed, composite applications. Services are usually simple to integrate, but often encapsulate complex and dynamic business logic with multiple variations and configurations. The fact that these services typically execute in a dynamic, unpredictable environment additionally complicates manageability and calls for adaptable management strategies. Current system control strategies mostly rely on static approaches, such as predefined policies. In this paper we propose a novel technique to improve management policies for complex service-based systems during runtime. This allows systems to adapt to changing environments, to circumvent unforeseen events and errors, and to resolve incompatibilities of composed services. Our approach requires no knowledge about the internals of services or service platforms, but analyzes log output to realize adaptive policies in a non-intrusive and generic way. Experiments in our testbed show that the approach is highly effective in avoiding incompatibilities and reducing the impact of defects in service implementations.

Wed, March 28, 16:20-18:00

• FTRMI: Fault-tolerant Transparent RMI
  Diogo Reis and Hugo Miranda

  A limitation of Remote Procedure Call systems (RPCs) is their single point of failure at the server side. To address this issue, a number of approaches extend RPCs syntax and semantic to encompass fault tolerance. However, this solution is neither transparent for the application programmer nor for the client. This paper describes a middleware platform that enhances JRMI with strong replica consistency. The middleware is completely transparent for the client and does not require recoding on the server side

• Timeout-based Adaptive Consensus: Improving Performance through Adaptation
  Mônica Dixit, Henrique Moniz and António Casimiro

  Algorithms for solving distributed systems problems often use timeouts as a means to achieve progress, even if these timeouts are encapsulated in failure detection services. They are designed in a way that safety is always preserved despite timeouts being too small or too large. A conservatively large static timeout value is usually selected, such that the overall system performance is acceptable in the normal case. This approach is good enough for applications that execute in stable environments, but it may compromise the system's performance in more dynamic settings, such as in wireless networks. In those cases, it is expected that adaptive solutions that automatically adjust timeouts according to the observed network conditions will perform better. This paper clearly illustrates the kind of improvements that may be achieved and thus justifies the importance of using adaptive protocols in dynamic environments. We describe our pragmatic approach to transform a static timeout-based consensus protocol for ad hoc wireless networks into an adaptive solution, using the services provided by the Adaptare framework. In particular, we explain how we are able to tune our adaptive solution for achieving the best performance, making it fully autonomic. Several experiments were performed in a wireless environment, which show that the adaptive solution is able to deal with varying end-to-end delays caused by uncertain network conditions, namely due to the changing number of nodes. In particular, with the adaptive solution the bandwidth utilization from each process is kept almost constant despite increasing the number of consensus participants, and the overall consensus execution time increases linearly instead of exponentially.

• Formal Verification of Unreliable Failure Detectors in Partially Synchronous Systems
  Muhammad Atif, Mohamamd Reza Mousavi and Ammar Osaiweran

  In this paper, we formally verify four algorithms proposed in [M. Larrea, S. Arevalo and A. Fernandez, Efficient Algorithms to Implement Unreliable Failure Detectors in Partially Synchronous Systems, 1999]. Each algorithm is specified formally as a network of timed automata and is verified with respect to completeness and accuracy properties. Using the model-checking tool UPPAAL, we detect and report the occurrences of deadlock (for all algorithms) between each pair of non-faulty nodes due to buffer overflow in communication channels with arbitrarily large buffers. We propose one solution for deadlock avoidance. Moreover, we use one of the algorithms studied in this paper as a measure to compare the effectiveness of three model-checking tools, namely, UPPAAL, mCRL2 and FDR2. We also show that all algorithms satisfy their completeness and accuracy properties if the required number of processes remain operational.

• Using Constraint-based Optimization and Variability to Support Continuous Self-Adaptation
  Carlos Parra, Daniel Romero, Sebastien Mosser, Romain Rouvoy, Laurence Duchien and Lionel Seinturier

  Self-adaptation is one of the upcoming paradigms that accurately tackles nowadays systems complexity. In this context, Dynamic Software Product Lines model the intrinsic variability of a family of systems, and dynamically support their reconfiguration according to updated context. However, when several configurations are available for the same context, making a decision about the right one is a hard challenge: further dimensions such as quality of service or reconfiguration cost are needed to enrich the decision making process. In this paper, we propose to combine variability with Constraint-Satisfaction Problem techniques to face this challenge. The approach is illustrated and then validated with the MobiHome example, an ubiquitous and context-driven system used to support the control of a home through mobile devices.

Poster session

TBD.

Track Program Co-Chairs

Important Dates