@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 {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} } @conference {17732, title = {Model-driven approach to design ICT infrastructure for precision farming}, booktitle = {17th IEEE Conference on Emerging Technologies and Factory Automation (ETFA)}, year = {2012}, month = {09/2012}, publisher = {IEEE Industrial Electronics Society}, organization = {IEEE Industrial Electronics Society}, address = {Krak{\'o}w, Poland}, abstract = {Design of complex systems involving a number of experts from various fields necessarily includes modeling at different levels of abstraction. Modeling is particularly important in the initial phase of a joint project when all system requirements and constraints have to be clearly defined and understood by all the partners. Once an unambiguous structural model has been achieved and components interfaces fixed, design of components can be done independently. For the initial phase, a very simplified modeling methodology based on UML that can be easily understood and applied has been proposed. The application of the methodology has been presented through the design of full structural model of the infrastructure for precision farming. Modeled infrastructure is an open ICT hardware-software solution based on ISOBUS specification, that enables partial automation of tractors increasing safety and production efficiency. Model achieved through several steps presents a mutual understanding platform between the partners. Most importantly, a precise model has been achieved without the necessity of in deep study of UML by all the partners.}, keywords = {agriculture, ICT infrastructure Design, ISOBUS, model-driven approach, precision farming, Safety, Unified Modeling Language}, isbn = {978-1-4673-4736-5}, doi = {10.1109/ETFA.2012.6489709}, author = {Kaitovi{\'c}, Igor and Rezende, Rafael and Murillo, Cristina and Fantuzzi, Cesare} }