Do we all really know what a fog node is? Current trends towards an open definition

Fog computing has emerged as a promising technology that can bring cloud applications closer to the physical IoT devices at the network edge. While it is widely known what cloud computing is, how data centers can build the cloud infrastructure and how applications can make use of this infrastructure, there is no common picture on what fog computing and particularly a fog node, as its main building block, really is. One of the first attempts to define a fog node was made by Cisco, qualifying a fog computing system as a “mini-cloud” located at the edge of the network and implemented through a variety of edge devices, interconnected by a variety, mostly wireless, communication technologies. Thus, a fog node would be the infrastructure implementing the said mini-cloud. Other proposals have their own definition of what a fog node is, usually in relation to a specific edge device, a specific use case or an application. In this paper, we first survey the state of the art in technologies for fog computing nodes, paying special attention to the contributions that analyze the role edge devices play in the fog node definition. We summarize and compare the concepts, lessons learned from their implementation, and end up showing how a conceptual framework is emerging towards a unifying fog node definition. We focus on core functionalities of a fog node as well as in the accompanying opportunities and challenges towards their practical realization in the near future.Postprint (author's final draft

Small mammals in a changing world: distributional, demographic and behavioural responses to environmental heterogeneity with implications for host-parasite-pathogen relationships

To upubliserte artikler har blitt fjernet fra den digitale versjonen, og kan leses i den trykte avhandlingen./Two unpublished articles have been removed from this digital version, and can be read in the printed thesis.Arters demografi og funksjonelle roller i miljøet er styrt av samspillet mellom individers iboende tilstand, abiotiske og biotiske forhold, inkludert mellom-artsforhold som vert-parasitt interaksjoner. Slike interaksjoner har generelt blitt undersøkt med langtidsserier og de mange ulike faktorene er lite vurdert. I denne avhandlingen, så har jeg brukt en multi-faktoriell nisje-basert tilnærming for å predikere små pattedyrs proksimate respons på miljø-, klima- og antropogene faktorer, og deres tidsromlige påvirkning på vert-parasitt-sykdom-mønstre. Det ble gjennomført levende fangst av småpattedyrsamfunnet på tvers av breddegrader (Norge og Italia) og over en høydegradient (fra 500 til 2500 moh.). Med et feltdesign som baserte seg på manipulering av mattilgjengelighet, og transekter langs heterogene habitat, vurderte jeg driverne i småpattedyrsamfunnets komposisjon og demografi, og kaskadeeffektene fra antall parasitter og overføring av både vanlige og nye patogener. Jeg fant at småpattedyrs overlevelse var avhengig av en iboende sesongsyklusitet og at den kun ble forsterket av mattilgjengelighet ved krevende værforhold. Likevel så var populasjonsstørrelsen hovedsakelig styrt av klimatiske begrensninger og mattilgjengelighet. Når opportunistiske og dominerende gnagere og ikke-dominer arter var sympatriske, så viste de motsatte demografiske tendenser i forhold til mattilgang der de ikke-dominerende artene fikk redusert overlevelse og populasjonsstørrelse, som indikerer utnyttelses- og interferenskonkurranse (Paper I). Når romlige komponenter i disse mønstrene ble kontrollert for, så fant jeg at mattilgangen for gnagere også reduserte deres romlige utbredelsesområde. Etterhvert som den lokale tettheten av de mest opportunistiske artene økte og jevnheten (evenness) ble redusert, så forsterket høye flått-tettheter gnagernes flåttbelastning, spesielt hos tyngre individer. I sum så vil en ansamling av primær- og sekundærverter på matstasjoner, og mer generelt i antropogene fragmenterte landskap, trolig øke sannsynligheten for å kunne fullføre flåttenes livssyklus. Dette induserer en forsterket flåttbelastningen i enkle vertssamfunn (Paper II). Langs den alpine høydegradienten fant vi støtte for at flått kan trives i et mildere klima som forårsaket av klimaendringer. I tråd med dette kan vertssamfunnets komposisjon og utbredelse over høydegradienten bli påvirket av klimarelaterte forhold. I samsvar med dette, fant jeg at generalister (som klatremus) også var utbredt på høyereliggende områder, de var sympatriske med arter mer tilpasset høyereliggende klima som snømarkmus og markmus. Denne endringen i distribusjonen av generalister og vektorer, var også fulgt av utbredelsen av vanlige gnager- og vektorbærte patogener som syntes å være fordelt på ulike høydenivåer, et aspekt som trenger videre studie (Paper III). Noen protozoer, som Hepatozoon spp. (Paper IV), kan spille en sterk epidemiologisk rolle gjennom næringsnettet. For å konkludere, denne avhandlingen har belyst flere økologiske komplekse forhold omkring små pattedyr i sårbare økosystem. På makro- og mikroskala, brukte vi eksperiment for å demonstrere konsekvenser fra klima og menneskelige forstyrrelser på små pattedyrs samfunn og populasjoner, og deres implikasjoner for menneskers og økosystemers helse.Abstract The demography of species and their functional role in the environment are governed by the interplay between individual internal state, external abiotic and biotic conditions, as well as by interspecific interactions, including host-parasite relationships. Generally, these interactions in wild systems have been investigated by long-term studies, and the different components were so far rarely evaluated ensemble. In this dissertation, I implemented a multi-factorial niche-based approach to predict small mammals’ proximate responses to environmental, climatic and anthropic factors, and their implications for host-parasite-disease spatio-temporal patterns. For this purpose, live-trapping targeting the small mammal community was performed across a wide latitudinal (Norway and Italy) and altitudinal (from 500 to 2500 m a.s.l.) gradient. Through field experimental designs based on manipulation of anthropogenic food availability, and longitudinal transects across heterogeneous habitats, I assessed the drivers of small mammal community composition and demography, and the cascading effects on the parasitic load and the circulation of common and emergent pathogens. I found that small mammal survival depended on intrinsic seasonal cycles and was enhanced by food availability only where harsh climate conditions occurred. Conversely, population size was mainly determined by climate constraints and food availability. When opportunistic, dominant rodent and subordinate vole species were sympatric, they showed opposite demographic trends in presence of anthropogenic food, with the subordinate species decreasing both survival and population size, likely pointing at exploitative and interference competition (Paper I). When the spatial components of these patterns were explicitly accounted for, I found that rodents also decreased their spatial range in presence of anthropogenic food. As the local density of the most opportunistic species increased and evenness decreased, their tick burden was amplified at high tick environmental density, especially in heavier individuals, and diluted at lower tick availability. To sum up, the overlap and aggregation of primary and secondary hosts at feeding sites, and more in general in anthropic, fragmented landscapes, likely enhances the completion of the tick life-cycle, inducing tick-burden amplification in a simplified community of hosts (Paper II). Ticks could also thrive in milder climatic conditions due to climate change, as observed along the Alpine altitudinal gradient. Similarly, the composition and altitudinal distribution of the host community can be affected by climate-related abiotic conditions. In accordance with this expectation, I detected the occurrence of generalist species (e.g. bank vole) also at high altitudes, so resulting sympatric with harsh climate specialists, such as snow and field voles. This upward distributional shift of generalist species, and vectors alongside, were also accompanied by circulation of common rodent- and vector-borne pathogens that seemed to show altitudinal segregation, an aspect that needs further investigation (Paper III). Among these, some protozoans, such as Hepatozoon spp. (Paper IV), that may hold a strong epidemiological role along the food web. In conclusion, this dissertation elucidated some complex ecological relationships that involve small mammals in sensitive ecosystems. At macro- and micro-scale, we experimentally demonstrated the cascading consequences of climate and anthropic disturbances on small mammal communities and populations, and their implications for the health of humans and ecosystems.publishedVersio

Many-Task Computing and Blue Waters

This report discusses many-task computing (MTC) generically and in the context of the proposed Blue Waters systems, which is planned to be the largest NSF-funded supercomputer when it begins production use in 2012. The aim of this report is to inform the BW project about MTC, including understanding aspects of MTC applications that can be used to characterize the domain and understanding the implications of these aspects to middleware and policies. Many MTC applications do not neatly fit the stereotypes of high-performance computing (HPC) or high-throughput computing (HTC) applications. Like HTC applications, by definition MTC applications are structured as graphs of discrete tasks, with explicit input and output dependencies forming the graph edges. However, MTC applications have significant features that distinguish them from typical HTC applications. In particular, different engineering constraints for hardware and software must be met in order to support these applications. HTC applications have traditionally run on platforms such as grids and clusters, through either workflow systems or parallel programming systems. MTC applications, in contrast, will often demand a short time to solution, may be communication intensive or data intensive, and may comprise very short tasks. Therefore, hardware and software for MTC must be engineered to support the additional communication and I/O and must minimize task dispatch overheads. The hardware of large-scale HPC systems, with its high degree of parallelism and support for intensive communication, is well suited for MTC applications. However, HPC systems often lack a dynamic resource-provisioning feature, are not ideal for task communication via the file system, and have an I/O system that is not optimized for MTC-style applications. Hence, additional software support is likely to be required to gain full benefit from the HPC hardware

InterCloud: Utility-Oriented Federation of Cloud Computing Environments for Scaling of Application Services

Cloud computing providers have setup several data centers at different geographical locations over the Internet in order to optimally serve needs of their customers around the world. However, existing systems do not support mechanisms and policies for dynamically coordinating load distribution among different Cloud-based data centers in order to determine optimal location for hosting application services to achieve reasonable QoS levels. Further, the Cloud computing providers are unable to predict geographic distribution of users consuming their services, hence the load coordination must happen automatically, and distribution of services must change in response to changes in the load. To counter this problem, we advocate creation of federated Cloud computing environment (InterCloud) that facilitates just-in-time, opportunistic, and scalable provisioning of application services, consistently achieving QoS targets under variable workload, resource and network conditions. The overall goal is to create a computing environment that supports dynamic expansion or contraction of capabilities (VMs, services, storage, and database) for handling sudden variations in service demands. This paper presents vision, challenges, and architectural elements of InterCloud for utility-oriented federation of Cloud computing environments. The proposed InterCloud environment supports scaling of applications across multiple vendor clouds. We have validated our approach by conducting a set of rigorous performance evaluation study using the CloudSim toolkit. The results demonstrate that federated Cloud computing model has immense potential as it offers significant performance gains as regards to response time and cost saving under dynamic workload scenarios.Comment: 20 pages, 4 figures, 3 tables, conference pape

Big Data and Large-scale Data Analytics: Efficiency of Sustainable Scalability and Security of Centralized Clouds and Edge Deployment Architectures

One of the significant shifts of the next-generation computing technologies will certainly be in the development of Big Data (BD) deployment architectures. Apache Hadoop, the BD landmark, evolved as a widely deployed BD operating system. Its new features include federation structure and many associated frameworks, which provide Hadoop 3.x with the maturity to serve different markets. This dissertation addresses two leading issues involved in exploiting BD and large-scale data analytics realm using the Hadoop platform. Namely, (i)Scalability that directly affects the system performance and overall throughput using portable Docker containers. (ii) Security that spread the adoption of data protection practices among practitioners using access controls. An Enhanced Mapreduce Environment (EME), OPportunistic and Elastic Resource Allocation (OPERA) scheduler, BD Federation Access Broker (BDFAB), and a Secure Intelligent Transportation System (SITS) of multi-tiers architecture for data streaming to the cloud computing are the main contribution of this thesis study

An Online Decision-Theoretic Pipeline for Responder Dispatch

The problem of dispatching emergency responders to service traffic accidents, fire, distress calls and crimes plagues urban areas across the globe. While such problems have been extensively looked at, most approaches are offline. Such methodologies fail to capture the dynamically changing environments under which critical emergency response occurs, and therefore, fail to be implemented in practice. Any holistic approach towards creating a pipeline for effective emergency response must also look at other challenges that it subsumes - predicting when and where incidents happen and understanding the changing environmental dynamics. We describe a system that collectively deals with all these problems in an online manner, meaning that the models get updated with streaming data sources. We highlight why such an approach is crucial to the effectiveness of emergency response, and present an algorithmic framework that can compute promising actions for a given decision-theoretic model for responder dispatch. We argue that carefully crafted heuristic measures can balance the trade-off between computational time and the quality of solutions achieved and highlight why such an approach is more scalable and tractable than traditional approaches. We also present an online mechanism for incident prediction, as well as an approach based on recurrent neural networks for learning and predicting environmental features that affect responder dispatch. We compare our methodology with prior state-of-the-art and existing dispatch strategies in the field, which show that our approach results in a reduction in response time with a drastic reduction in computational time.Comment: Appeared in ICCPS 201