@conference {18165,
	title = {ExCovery {\textendash} A Framework for Distributed System Experiments and a Case Study of Service Discovery},
	booktitle = {28th International Parallel \& Distributed Processing Symposium, Workshops and Phd Forum (IPDPSW)},
	year = {2014},
	month = {05/2014},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Phoenix, AZ, USA},
	abstract = {Experiments are a fundamental part of science. They are needed when the system under evaluation is too complex to be analytically described and they serve to empirically validate hypotheses. This work presents the experimentation framework <i>ExCovery</i> for dependability analysis of distributed processes. It provides concepts that cover the description, execution, measurement and storage of experiments. These concepts foster transparency and repeatability of experiments for further sharing and comparison. <i>ExCovery</i> has been tried and refined in a manifold of dependability related experiments during the last two years. A case study is provided to describe service discovery as experiment process. A working prototype for IP networks runs on the Distributed Embedded System (DES) wireless testbed at the Freie Universit{\"a}t Berlin.},
	keywords = {Distributed Systems, Experiment Framework, Experiments, Tool Description},
	isbn = {978-1-4799-4116-2/14},
	doi = {10.1109/IPDPSW.2014.147},
	url = {http://andreas-dittrich.eu/2014/03/excovery},
	author = {Dittrich, Andreas and Wanja, Stefan and Malek, Miroslaw}
}
@inbook {18024,
	title = {Modeling Responsiveness of Decentralized Service Discovery in Wireless Mesh Networks},
	booktitle = {MMB \& DFT},
	series = {Lecture Notes in Computer Science},
	volume = {8376},
	year = {2014},
	pages = {88-102},
	publisher = {Springer International Publishing Switzerland},
	organization = {Springer International Publishing Switzerland},
	abstract = {In modern service networks, discovery plays a crucial role as a layer where providing instances of a given service can be published and enumerated. Since successful discovery is mandatory for service usage, comprehensive service dependability assessment needs to incorporate the dependability of the discovery layer. This work focuses on the responsiveness of the discovery layer, the probability to operate successfully within a deadline, even in the presence of faults. It proposes a hierarchy of stochastic models for decentralized discovery and uses it to describe the discovery of a single service using three well-known discovery protocols: domain name system based service discovery (DNS-SD), simple service discovery protocol (SSDP) and service location protocol (SLP). Further, a methodology to use the model hierarchy in wireless mesh networks is introduced. Given a pair service requester and provider, a discovery protocol and a deadline, it estimates packet loss probabilities and transmission time distributions for each link on the communication paths between the pair, generates specific model instances and calculates the expected responsiveness. Finally, the paper introduces a new metric, the expected responsiveness distance d_er to estimate the maximum distance from a provider where requesters are still able to discover it with a required responsiveness. The models and their methodology are demonstrated using monitoring data from the distributed embedded systems (DES) testbed at Freie Universit{\"a}t Berlin. It is shown how the responsiveness and d_er of the protocols change depending on the position of requester and provider and the overall link quality in the network.},
	keywords = {fault tolerance, Markov Models, Real time systems, Responsiveness, Service Discovery, Wireless mesh networks},
	isbn = {978-3-319-05358-5},
	issn = {0302-9743},
	doi = {10.1007/978-3-319-05359-2_7},
	url = {http://andreas-dittrich.eu/2013/12/modeling-responsiveness-of-decentralized-service-discovery-in-wireless-mesh-networks},
	author = {Dittrich, Andreas and Lichtblau, Bj{\"o}rn and Rezende, Rafael and Malek, Miroslaw},
	editor = {Fischbach, K. and Krieger, U. R.}
}
@conference {18043,
	title = {Probabilistic Breadth-First Search {\textendash} A Method for Evaluation of Network-Wide Broadcast Protocols},
	booktitle = {6th IEEE/ACM/IFIP International Conference on New Technologies, Mobility and Security (NTMS)},
	year = {2014},
	month = {03/2014},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Dubai, UAE},
	abstract = {In wireless mesh networks (WMNs), network-wide broadcasts (NWBs) are a fundamental operation, required by routing and other mechanisms that distribute information to all nodes in the network. However, due to the characteristics of wireless communication, NWBs are generally problematic. Optimizing them is thus a prime target when improving the overall performance and dependability of WMNs. Most of the existing optimizations neglect the real nature of WMNs and are based on simple graph models, which provide optimistic assumptions of NWB dissemination. On the other hand, models that fully consider the complex propagation characteristics of NWBs quickly become unsolvable due to their complexity. In this paper, we present the Monte Carlo method probabilistic breadth-first search (PBFS) to approximate the reachability of NWB protocols. PBFS simulates individual NWBs on graphs with probabilistic edge weights, which reflect link qualities of individual wireless links in the WMN, and estimates reachability over a configurable number of simulated runs. This approach is not only more efficient than existing ones, but further provides additional information such as the distribution of path lengths. Furthermore, it is easily extensible to NWB schemes other than flooding. The applicability of PBFS is validated both theoretically and empirically, in the latter by comparing reachability as calculated by PBFS and measured in a real-world WMN. Validation shows that PBFS quickly converges to the theoretically correct value and approximates the behaviour of real-life testbeds very well. The feasibility of PBFS to support research on NWB optimizations or higher level protocols that employ NWBs is demonstrated in two use cases.},
	keywords = {Monte Carlo methods, Network-wide broadcasts, Probabilistic network graphs, Wireless mesh networks},
	isbn = {9781479932238},
	doi = {10.1109/NTMS.2014.6814046},
	url = {http://andreas-dittrich.eu/2014/01/pbfs},
	author = {Lichtblau, Bj{\"o}rn and Dittrich, Andreas}
}
@conference {18206,
	title = {A Resource-optimized Approach to Efficient Early Detection of Mobile Malware},
	booktitle = {3rd International Workshop on Security of Mobile Applications - IWSMA 2014},
	year = {2014},
	month = {09/2014},
	address = {Fribourg, Switzerland},
	author = {Milosevic, Jelena and Dittrich, Andreas and Ferrante, Alberto and Malek, Miroslaw}
}
@conference {18232,
	title = {Responsiveness of Service Discovery in Wireless Mesh Networks},
	booktitle = {20th Pacific Rim International Symposium on Dependable Computing (PRDC)},
	year = {2014},
	month = {11/2014},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Singapore},
	abstract = {Service Discovery (SD) is an integral part of service networks. Before a service can be used, it needs to be discovered successfully. Comprehensive service dependability analysis thus needs to include the SD process. As a time-critical operation, an important property of SD is responsiveness: The probability of successful discovery within a deadline, even in the presence of faults. This is especially true for dynamic networks with complex fault behavior such as wireless networks. This work evaluates the responsiveness of decentralized SD in wireless mesh networks. For this reason, the experiment framework ExCovery has been employed, which provides a unified description, execution, measurement and storage of experiments. ExCovery runs on the Distributed Embedded System (DES) wireless testbed at Freie Universit{\"a}t Berlin. We present and discuss the results of the experiments and show how responsiveness is affected by the position and number of requester and providers as well as the load in the network. The results clearly demonstrate that in all but the most favorable conditions, the configurations of current SD protocols struggle to achieve a high responsiveness.},
	keywords = {Experiments, Responsiveness, Service Discovery, Wireless mesh networks, Zeroconf},
	doi = {10.1109/PRDC.2014.38},
	url = {http://andreas-dittrich.eu/2014/06/prdc2014},
	author = {Dittrich, Andreas and Herrera, Daniel Solis and Coto, Pablo and Malek, Miroslaw}
}
@conference {18227,
	title = {Risk Assessment of Atrial Fibrillation: a Failure Prediction Approach},
	booktitle = {41st Computing in Cardiology Conference (CinC)},
	year = {2014},
	month = {09/2014},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Cambridge, MA, USA},
	abstract = {We present a methodology for identifying patients who have experienced Paroxysmal Atrial Fibrillation (PAF) among a given subjects population. Our work is intended as an initial step towards the design of an unobtrusive system for concurrent detection and monitoring of chronic cardiac conditions.

Our methodology comprises two stages: off-line training and on-line analysis. During training the most significant features are selected using machine-learning methods, without relying on a manual selection based on previous knowledge. Analysis is based on two phases: feature extraction and detection of PAF patients. Light-weight algorithms are employed in the feature extraction phase, allowing the on-line implementation of this step on wearable and resource-constrained sensor nodes. The detection phase employs techniques borrowed from the field of failure prediction. While these algorithms have found extensive applications in diverse scenarios, their application to automated cardiac analysis has not been sufficiently investigated.

Obtained results, in terms of performance, are comparable to similar efforts in the field. Nonetheless, the proposed method employs computationally simpler and more efficient algorithms, which are compatible with the computational constraints of state-of-the-art body sensor nodes.},
	url = {http://andreas-dittrich.eu/2014/06/risk-assessment-of-atrial-fibrillation-a-failure-prediction-approach},
	author = {Milosevic, Jelena and Dittrich, Andreas and Ferrante, Alberto and Malek, Miroslaw and Rojas Quiros, Camilo and Braojos, Rub{\'e}n and Ansaloni, Giovanni and Atienza, David}
}
@conference {17729,
	title = {A Model for the Evaluation of User-Perceived Service Properties},
	booktitle = {International Symposium on Parallel Distributed Processing, Workshops and Phd Forum (IPDPSW)},
	year = {2013},
	month = {May},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Boston, Massachusetts, USA},
	abstract = {An ever-increasing number of both functional and non-functional requirements has resulted in growing system complexity which demands new solutions in system modeling and evaluation. As a remedy, service-oriented architecture (SOA) offers services as basic building elements of system design. Service dependability is highly dependent on the properties of the underlying information and communications technology (ICT) infrastructure. This is especially true for the user-perceived dependability of a specific pair service client and provider as every pair may utilize different ICT components. We provide a model for the description of ICT components and their non-functional properties based on the Unified Modeling Language (UML). Given a service description, a network topology model and a pair service client and provider, we propose a methodology to automatically identify relevant ICT components and generate a user-perceived service infrastructure model (UPSIM). We demonstrate the feasibility of the methodology by applying it to parts of the service network infrastructure at Universit{\`a} della Svizzera italiana, Switzerland. We then show how this methodology can be used to facilitate user-perceived service dependability analysis.},
	keywords = {availability, design engineering, metamodeling, modeling, object oriented modeling, quality of service (QoS), service dependability, service network management, service networks},
	isbn = {978-0-7695-4979-8},
	doi = {10.1109/IPDPSW.2013.163},
	url = {http://andreas-dittrich.eu/2013/03/a-model-for-the-evaluation-of-user-perceived-service-properties},
	author = {Dittrich, Andreas and Kaitovi{\'c}, Igor and Murillo, Cristina and Rezende, Rafael}
}
@inbook {17731,
	title = {Model-Driven Evaluation of User-Perceived Service Availability},
	booktitle = {Dependable Computing},
	series = {Lecture Notes in Computer Science},
	volume = {7869},
	year = {2013},
	month = {May},
	pages = {39-53},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	abstract = {Service-oriented architecture (SOA), which proposes services as basic building elements of system design, has emerged as an approach to master growing system complexity. However, it remains difficult to evaluate dependability of such distributed and heterogeneous functionality as it depends highly on the properties of the enabling information and communications technology (ICT) infrastructure. Moreover, every specific pair service client and provider can utilize different ICT components, constituting for the user-perceived view of a service. We provide a model-driven methodology to automatically create reliability block diagrams of such views. Given a service description, a network topology model and a pair service client and provider, it identifies relevant ICT components and generates a user-perceived service availability model (UPSAM). We then use this UPSAM to calculate the steady-state availability of different views on an examplary mail service deployed in the network infrastructure of University of Lugano.},
	keywords = {availability, design engineering, modeling, object oriented modeling, quality of service (QoS), service dependability, service network management, service networks},
	issn = {978-3-642-38788-3},
	doi = {10.1007/978-3-642-38789-0_4},
	url = {http://andreas-dittrich.eu/2013/04/model-driven-evaluation-of-user-perceived-service-availability},
	author = {Dittrich, Andreas and Rezende, Rafael},
	editor = {Vieira, Marco and Cunha, Jo{\~a}o Carlos}
}
@conference {17846,
	title = {User-Perceived Instantaneous Service Availability Evaluation},
	booktitle = {19th Pacific Rim International Symposium on Dependable Computing (PRDC)},
	year = {2013},
	month = {12/2013},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Vancouver, British Columbia, Canada},
	abstract = {Today{\textquoteright}s businesses rely ever more on dependable service provision deployed on information and communications technology (ICT) infrastructures. Service dependability is highly influenced by the individual infrastructure component properties. Combining these properties for consistent dependability analysis is challenging as every service requester might use a different set of components during service usage, constituting the user-perceived view on a service. This paper presents a methodology to evaluate user-perceived instantaneous service availability. It uses three input models: (1) The ICT infrastructure, with failure rates, repair rates and deployment times of all components, (2) an abstract description of complex hierarchical services, (3) a mapping that contains concrete ICT components for the service pair requester and provider, as well as their existing replicas, and a duration of usage. The methodology then automatically generates an availability model from those parts of the ICT infrastructure needed during provision for the specified pair. To calculate instantaneous availability, the age of the ICT components, the order and time of their usage during service provision are taken into account. The methodology supports generation of different availability models, we demonstrate this by providing reliability block diagrams and fault-trees. We demonstrate the feasibility of the methodology by applying it to parts of the network infrastructure of Universit{\`a} della Svizzera italiana, Switzerland.},
	keywords = {availability, Client-server systems, Distributed computing, fault tolerance, modeling},
	doi = {10.1109/PRDC.2013.49},
	url = {http://andreas-dittrich.eu/2013/08/user-perceived-instantaneous-service-availability-evaluation},
	author = {Rezende, Rafael and Dittrich, Andreas and Malek, Miroslaw}
}
