In order to fully benefit from cloud computing, services are designed following the “multi-tenant” architectural model which is aimed at maximizing resource sharing among users. However, multi-tenancy introduces challenges of security, performance isolation, scaling and customization. RStudio server is an open source Integrated Development Environment (IDE) accessible over a web browser for R programming language. The purpose of this thesis is to develop an open source multi-user distributed system on Hopsworks, a data intensive and AI platform, following the multi-tenant model, that provides RStudio as Software as a Service (SaaS). Our goal is to promote collaboration among users when using RStudio and the learning and teaching of R by enabling users easily have access to same computational environments and resources while eliminating installation and maintenance tasks. Hopsworks introduces project-based multi-tenancy where users within a project share project resources (e.g datasets, programs and services) for collaboration which introduces one more challenge of sharing project resources in RStudio server instances. To achieve our purpose and goal we therefore needed to solve the following problems: performance isolation, security, project resources sharing, scaling and customization. Our proposed model is on demand single user RStudio server instances per project. Our system is built around Docker and Kubernetes to solve the problems of performance isolation, security and scaling. We introduce HopsFS-mount, that allows securely mounting HopsFS via FUSE to solve the project resources (datasets and programs) sharing problem. We integrate our system with Apache Spark which can scale and handle Big Data processing workloads. Also we provide a UI where users can provide custom configuration and have full control of their own RStudio server instances. Our system was tested on a GCP cluster with four worker nodes each with 30GB of RAM allocated to them. The tests on this cluster showed that 44 RStudio servers, each with 2GB of RAM, can be run concurrently. Our system can scale out to potentially support hundreds of concurrently running RStudio servers by adding more resources (CPUs and RAM) to the cluster or system. / För att dra full nytta av molntjänster är vissa applikationer designade för multitenans som syftar till att maximera resursdelning mellan användare. Dock introducerar multitenans utmaningar i hänsyn till resursdelning, säkerhet, prestandaisolering, anpassning och skalning. RStudio-server är en öppen källkod Integrerad utvecklingsmiljö (IDE) tillgänglig över en webbläsare för programmeringsspråket R. Syftet med denna avhandling är att utveckla ett distribuerat system med öppen källkod för flera användare på Hopsworks, en data krävande AI-plattform, efter multitenans-modellen, som tillhandahåller RStudio som Software as a Service (SaaS). Vårt mål är att främja samarbete mellan användare vid användning av RStudio, inlärning och undervisning av R genom att göra det enkelt för användare att ha tillgång till samma beräknings miljöer och resurser samtidigt som installation och underhållsarbete elimineras. Hopsworks introducerar projektbaserad multitenans där användare inom ett projekt delar projektresurser (t.ex. datamängder, program och tjänster) för samarbete som introducerar ytterligare en utmaning att dela projektresurser i RStudio server instanser. För att uppnå vårt syfte och mål behövde vi därför lösa följande problem: prestandaisolering, säkerhet, projekt resursdelning, skalning och anpassning. Vår föreslagna modell är på bergäran en-användares RStudio-serverinstanser per projekt. Vårt system är byggt kring Docker och Kubernetes för att lösa problemen med prestanda isolering, säkerhet och skalning. Vi introducerar HopsFS-mount, som gör det möjligt att säkert montera HopsFS via FUSE för att lösa resurs (datamängder och program) delning problemet. Vi integrerar vårt system med Apache Spark som kan skala och hantera Big Data bearbetning belastningar. Vi tillhandahåller också ett användargränssnitt där användare kan tillhandahålla anpassad konfiguration och ha full kontroll över sina egna RStudio-serverinstanser. Vårt system testades på ett GCP-kluster med fyra arbets noder, varje node hade 30 GB RAM. Testerna på detta kluster visade att 44 RStudio-servrar, var och en med 2 GB RAM, kan köras samtidigt. Vårt system kan även skala ut för att potentiellt stödja hundratals RStudio-servrar som samtidigt körs genom att lägga till fler resurser (CPU:er och RAM) i klustret eller systemet.

Univ., Diss.--Göteborg, 2007. / Enth. 4 Beitr.

Previous studies by Thomson (1996) and Crookes (2002) in land rental markets of rural KwaZulu-Natal were based on the premise that rental markets brought about efficiency and equity gains. Indeed these gains were proven by econometric analyses in both studies. Poor households that lacked the labour, time and other resources to farm land prior to the introduction of the rental market, tended to leave their arable land idle. In participating in rental transactions, land transferred from these poor households to households with the resources and the willingness to farm; and rental income was earned by the poor households. The current 2003/4 survey sought to evaluate the gains in two new areas, Mhlungwini in the Estcourt District and Duduza in the Bergville District, not covered in previous studies. Institutional interventions, related to the land rental market, in Mhlungwini and Duduza, had started in 2000 and 1993 respectively. Equity and efficiency gains were again proven as Lyne (2004) reports. While Chapter 2 provides an in-depth review of literature related to the theory of economic institutions, Chapter 3 applies this knowledge to Thomson's (1996) pilot project on institutional reform. This project, in terms of its action research that bore the ex ante transaction costs of willing participants, set in motion a process of institutional change leading to the development of the land rental market. The introduction of a formal contract, approved by the tribal authorities, served to give credence to rental transactions. In addition, institutional changes were made to reduce the likelihood of crop damage by stray cattle on arable land, in order to encourage willingness of households to lease in land. Recommendations were made by Thomson (1996) to further increase the exclusivity of arable land property rights. Options were evaluated by the author for institutional reform of communal grazing resources. This is to prevent degradation of grazing land caused by overstocking. Recommendations were made to promote sustainable use of the land. Chapter 4, apart from briefly analyzing the current survey results, provides two comparative studies of institutional reform, the first related to Australian water resources and the second related to land registration experiences in Africa. The last section of the Chapter evaluates a proposal for introduction of formal financial services to rural farmers. / Thesis (M.A.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Esta dissertação toma como objeto as relações e práticas de arrendamentos rurais estabelecidas entre 1847 e 1910 em Uruguaiana, município situado na fronteira do Brasil com Argentina e Uruguai. Ali predomina a paisagem agrária conhecida como “Campanha rio-grandense”, que se caracteriza pela vastidão de campos nos quais a principal atividade econômica desempenhada desde os tempos coloniais foi a pecuária. O aumento da incidência de arrendamento de terra e gado ao longo de seis décadas analisadas refletia os efeitos da crise de mão-de-obra escrava - base importante da pecuária local - e do fechamento gradativo do acesso à terra naquele contexto. Assim, esses contratos configuraram-se como alternativas de acesso aos meios de produção diante desse quadro, principalmente para aqueles produtores que ocupavam parcelas de terra sem possuir a propriedade jurídica das mesmas, cuja existência era cada vez menos tolerada pelos proprietários. No entanto, os arrendamentos integravam uma gama mais ampla de contratos firmados no mundo agrário, com limites jurídicos não muito precisos, que poderiam responder a demandas de produtores não totalmente desprovidos do acesso à terra, interessados em reproduzir os expedientes da pecuária extensiva praticada na Campanha. Os contratos também implicavam relações de propriedade encarnadas pelas cláusulas contratuais, e estas manifestavam diferentes aspectos das mesmas, que passavam por um processo de redefinição na segunda metade do século XIX. Este contexto estava permeado por conflitos que muitas vezes chegaram às vias judiciais, colocando frente a frente distintas concepções sobre direitos de propriedade. Muitos arrendatários foram protagonistas dessas disputas, e conseqüentemente, contribuíram para a complexidade assumida pelo processo de transformação pelo qual passavam a propriedade fundiária e as relações socioeconômicas no meio rural brasileiro do período. / This dissertation takes as its object the relations and practices of rural tenancies established between 1847-1910 in Uruguaiana, a county located in the Brazilian border with Argentina and Uruguay. In that region, the prevailing agrarian landscape is known as “Campanha rio-grandense”, characterized by the expanse of fields in which the main economical activity fulfilled since colonial times was ranching. The increase of the incidence of land and cattle tenancies along the six decades analyzed mirrored the effects of the slave labor crisis – an important basis of local ranching – and of the access to land gradual closure in such context. Therefore, these contracts constituted themselves as alternatives to the access to means of production in the face of this picture, chiefly to those producers who occupied land plots without having juridical property, whose existence had been less and less tolerated by the land owners. However, tenancies integrated a wider range of contracts subscribed in the “Campanha”. The contracts also implicated relations of property embodied by contractual clauses, and these ones manifested different aspects of such relations, which were passing through a redefinition process in the second half of the nineteenth century. This context was pervaded by conflicts that many times reached the judicial ways, putting face to face distinct conceptions about rights of property. Many tenants were protagonists of these disputes and consequently contributed to the complexity took on by the transformation process through which land property and socioeconomic relations passed in the Brazilian rural environment.

Esta dissertação toma como objeto as relações e práticas de arrendamentos rurais estabelecidas entre 1847 e 1910 em Uruguaiana, município situado na fronteira do Brasil com Argentina e Uruguai. Ali predomina a paisagem agrária conhecida como “Campanha rio-grandense”, que se caracteriza pela vastidão de campos nos quais a principal atividade econômica desempenhada desde os tempos coloniais foi a pecuária. O aumento da incidência de arrendamento de terra e gado ao longo de seis décadas analisadas refletia os efeitos da crise de mão-de-obra escrava - base importante da pecuária local - e do fechamento gradativo do acesso à terra naquele contexto. Assim, esses contratos configuraram-se como alternativas de acesso aos meios de produção diante desse quadro, principalmente para aqueles produtores que ocupavam parcelas de terra sem possuir a propriedade jurídica das mesmas, cuja existência era cada vez menos tolerada pelos proprietários. No entanto, os arrendamentos integravam uma gama mais ampla de contratos firmados no mundo agrário, com limites jurídicos não muito precisos, que poderiam responder a demandas de produtores não totalmente desprovidos do acesso à terra, interessados em reproduzir os expedientes da pecuária extensiva praticada na Campanha. Os contratos também implicavam relações de propriedade encarnadas pelas cláusulas contratuais, e estas manifestavam diferentes aspectos das mesmas, que passavam por um processo de redefinição na segunda metade do século XIX. Este contexto estava permeado por conflitos que muitas vezes chegaram às vias judiciais, colocando frente a frente distintas concepções sobre direitos de propriedade. Muitos arrendatários foram protagonistas dessas disputas, e conseqüentemente, contribuíram para a complexidade assumida pelo processo de transformação pelo qual passavam a propriedade fundiária e as relações socioeconômicas no meio rural brasileiro do período. / This dissertation takes as its object the relations and practices of rural tenancies established between 1847-1910 in Uruguaiana, a county located in the Brazilian border with Argentina and Uruguay. In that region, the prevailing agrarian landscape is known as “Campanha rio-grandense”, characterized by the expanse of fields in which the main economical activity fulfilled since colonial times was ranching. The increase of the incidence of land and cattle tenancies along the six decades analyzed mirrored the effects of the slave labor crisis – an important basis of local ranching – and of the access to land gradual closure in such context. Therefore, these contracts constituted themselves as alternatives to the access to means of production in the face of this picture, chiefly to those producers who occupied land plots without having juridical property, whose existence had been less and less tolerated by the land owners. However, tenancies integrated a wider range of contracts subscribed in the “Campanha”. The contracts also implicated relations of property embodied by contractual clauses, and these ones manifested different aspects of such relations, which were passing through a redefinition process in the second half of the nineteenth century. This context was pervaded by conflicts that many times reached the judicial ways, putting face to face distinct conceptions about rights of property. Many tenants were protagonists of these disputes and consequently contributed to the complexity took on by the transformation process through which land property and socioeconomic relations passed in the Brazilian rural environment.

Esta dissertação toma como objeto as relações e práticas de arrendamentos rurais estabelecidas entre 1847 e 1910 em Uruguaiana, município situado na fronteira do Brasil com Argentina e Uruguai. Ali predomina a paisagem agrária conhecida como “Campanha rio-grandense”, que se caracteriza pela vastidão de campos nos quais a principal atividade econômica desempenhada desde os tempos coloniais foi a pecuária. O aumento da incidência de arrendamento de terra e gado ao longo de seis décadas analisadas refletia os efeitos da crise de mão-de-obra escrava - base importante da pecuária local - e do fechamento gradativo do acesso à terra naquele contexto. Assim, esses contratos configuraram-se como alternativas de acesso aos meios de produção diante desse quadro, principalmente para aqueles produtores que ocupavam parcelas de terra sem possuir a propriedade jurídica das mesmas, cuja existência era cada vez menos tolerada pelos proprietários. No entanto, os arrendamentos integravam uma gama mais ampla de contratos firmados no mundo agrário, com limites jurídicos não muito precisos, que poderiam responder a demandas de produtores não totalmente desprovidos do acesso à terra, interessados em reproduzir os expedientes da pecuária extensiva praticada na Campanha. Os contratos também implicavam relações de propriedade encarnadas pelas cláusulas contratuais, e estas manifestavam diferentes aspectos das mesmas, que passavam por um processo de redefinição na segunda metade do século XIX. Este contexto estava permeado por conflitos que muitas vezes chegaram às vias judiciais, colocando frente a frente distintas concepções sobre direitos de propriedade. Muitos arrendatários foram protagonistas dessas disputas, e conseqüentemente, contribuíram para a complexidade assumida pelo processo de transformação pelo qual passavam a propriedade fundiária e as relações socioeconômicas no meio rural brasileiro do período. / This dissertation takes as its object the relations and practices of rural tenancies established between 1847-1910 in Uruguaiana, a county located in the Brazilian border with Argentina and Uruguay. In that region, the prevailing agrarian landscape is known as “Campanha rio-grandense”, characterized by the expanse of fields in which the main economical activity fulfilled since colonial times was ranching. The increase of the incidence of land and cattle tenancies along the six decades analyzed mirrored the effects of the slave labor crisis – an important basis of local ranching – and of the access to land gradual closure in such context. Therefore, these contracts constituted themselves as alternatives to the access to means of production in the face of this picture, chiefly to those producers who occupied land plots without having juridical property, whose existence had been less and less tolerated by the land owners. However, tenancies integrated a wider range of contracts subscribed in the “Campanha”. The contracts also implicated relations of property embodied by contractual clauses, and these ones manifested different aspects of such relations, which were passing through a redefinition process in the second half of the nineteenth century. This context was pervaded by conflicts that many times reached the judicial ways, putting face to face distinct conceptions about rights of property. Many tenants were protagonists of these disputes and consequently contributed to the complexity took on by the transformation process through which land property and socioeconomic relations passed in the Brazilian rural environment.

This diploma thesis is focused on the analysis and comparison of rental flats in Jihlava and factors that influence the amount of rent. The work contains text and graphics part. For the analysis were used dispositions 1+kk, 1+1, 2+kk, 2+1, 3+kk a 3+1. The assessment of these dispositions is given in the tables and graphs. The result of the thesis is the evaluation of the factors which influence the price of rental flats.

Tesis por compendio / [ES] Las aplicaciones científicas implican generalmente una carga computacional variable y no predecible a la que las instituciones deben hacer frente variando dinámicamente la asignación de recursos en función de las distintas necesidades computacionales. Las aplicaciones científicas pueden necesitar grandes requisitos. Por ejemplo, una gran cantidad de recursos computacionales para el procesado de numerosos trabajos independientes (High Throughput Computing o HTC) o recursos de alto rendimiento para la resolución de un problema individual (High Performance Computing o HPC). Los recursos computacionales necesarios en este tipo de aplicaciones suelen acarrear un coste muy alto que puede exceder la disponibilidad de los recursos de la institución o estos pueden no adaptarse correctamente a las necesidades de las aplicaciones científicas, especialmente en el caso de infraestructuras preparadas para la ejecución de aplicaciones de HPC. De hecho, es posible que las diferentes partes de una aplicación necesiten distintos tipos de recursos computacionales. Actualmente las plataformas de servicios en la nube se han convertido en una solución eficiente para satisfacer la demanda de las aplicaciones HTC, ya que proporcionan un abanico de recursos computacionales accesibles bajo demanda. Por esta razón, se ha producido un incremento en la cantidad de clouds híbridos, los cuales son una combinación de infraestructuras alojadas en servicios en la nube y en las propias instituciones (on-premise). Dado que las aplicaciones pueden ser procesadas en distintas infraestructuras, actualmente la portabilidad de las aplicaciones se ha convertido en un aspecto clave. Probablemente, las tecnologías de contenedores son la tecnología más popular para la entrega de aplicaciones gracias a que permiten reproducibilidad, trazabilidad, versionado, aislamiento y portabilidad. El objetivo de la tesis es proporcionar una arquitectura y una serie de servicios para proveer infraestructuras elásticas híbridas de procesamiento que puedan dar respuesta a las diferentes cargas de trabajo. Para ello, se ha considerado la utilización de elasticidad vertical y horizontal desarrollando una prueba de concepto para proporcionar elasticidad vertical y se ha diseñado una arquitectura cloud elástica de procesamiento de Análisis de Datos. Después, se ha trabajo en una arquitectura cloud de recursos heterogéneos de procesamiento de imágenes médicas que proporciona distintas colas de procesamiento para trabajos con diferentes requisitos. Esta arquitectura ha estado enmarcada en una colaboración con la empresa QUIBIM. En la última parte de la tesis, se ha evolucionado esta arquitectura para diseñar e implementar un cloud elástico, multi-site y multi-tenant para el procesamiento de imágenes médicas en el marco del proyecto europeo PRIMAGE. Esta arquitectura utiliza un almacenamiento distribuido integrando servicios externos para la autenticación y la autorización basados en OpenID Connect (OIDC). Para ello, se ha desarrollado la herramienta kube-authorizer que, de manera automatizada y a partir de la información obtenida en el proceso de autenticación, proporciona el control de acceso a los recursos de la infraestructura de procesamiento mediante la creación de las políticas y roles. Finalmente, se ha desarrollado otra herramienta, hpc-connector, que permite la integración de infraestructuras de procesamiento HPC en infraestructuras cloud sin necesitar realizar cambios en la infraestructura HPC ni en la arquitectura cloud. Cabe destacar que, durante la realización de esta tesis, se han utilizado distintas tecnologías de gestión de trabajos y de contenedores de código abierto, se han desarrollado herramientas y componentes de código abierto y se han implementado recetas para la configuración automatizada de las distintas arquitecturas diseñadas desde la perspectiva DevOps. / [CA] Les aplicacions científiques impliquen generalment una càrrega computacional variable i no predictible a què les institucions han de fer front variant dinàmicament l'assignació de recursos en funció de les diferents necessitats computacionals. Les aplicacions científiques poden necessitar grans requisits. Per exemple, una gran quantitat de recursos computacionals per al processament de nombrosos treballs independents (High Throughput Computing o HTC) o recursos d'alt rendiment per a la resolució d'un problema individual (High Performance Computing o HPC). Els recursos computacionals necessaris en aquest tipus d'aplicacions solen comportar un cost molt elevat que pot excedir la disponibilitat dels recursos de la institució o aquests poden no adaptar-se correctament a les necessitats de les aplicacions científiques, especialment en el cas d'infraestructures preparades per a l'avaluació d'aplicacions d'HPC. De fet, és possible que les diferents parts d'una aplicació necessiten diferents tipus de recursos computacionals. Actualment les plataformes de servicis al núvol han esdevingut una solució eficient per satisfer la demanda de les aplicacions HTC, ja que proporcionen un ventall de recursos computacionals accessibles a demanda. Per aquest motiu, s'ha produït un increment de la quantitat de clouds híbrids, els quals són una combinació d'infraestructures allotjades a servicis en el núvol i a les mateixes institucions (on-premise). Donat que les aplicacions poden ser processades en diferents infraestructures, actualment la portabilitat de les aplicacions s'ha convertit en un aspecte clau. Probablement, les tecnologies de contenidors són la tecnologia més popular per a l'entrega d'aplicacions gràcies al fet que permeten reproductibilitat, traçabilitat, versionat, aïllament i portabilitat. L'objectiu de la tesi és proporcionar una arquitectura i una sèrie de servicis per proveir infraestructures elàstiques híbrides de processament que puguen donar resposta a les diferents càrregues de treball. Per a això, s'ha considerat la utilització d'elasticitat vertical i horitzontal desenvolupant una prova de concepte per proporcionar elasticitat vertical i s'ha dissenyat una arquitectura cloud elàstica de processament d'Anàlisi de Dades. Després, s'ha treballat en una arquitectura cloud de recursos heterogenis de processament d'imatges mèdiques que proporciona distintes cues de processament per a treballs amb diferents requisits. Aquesta arquitectura ha estat emmarcada en una col·laboració amb l'empresa QUIBIM. En l'última part de la tesi, s'ha evolucionat aquesta arquitectura per dissenyar i implementar un cloud elàstic, multi-site i multi-tenant per al processament d'imatges mèdiques en el marc del projecte europeu PRIMAGE. Aquesta arquitectura utilitza un emmagatzemament integrant servicis externs per a l'autenticació i autorització basats en OpenID Connect (OIDC). Per a això, s'ha desenvolupat la ferramenta kube-authorizer que, de manera automatitzada i a partir de la informació obtinguda en el procés d'autenticació, proporciona el control d'accés als recursos de la infraestructura de processament mitjançant la creació de les polítiques i rols. Finalment, s'ha desenvolupat una altra ferramenta, hpc-connector, que permet la integració d'infraestructures de processament HPC en infraestructures cloud sense necessitat de realitzar canvis en la infraestructura HPC ni en l'arquitectura cloud. Es pot destacar que, durant la realització d'aquesta tesi, s'han utilitzat diferents tecnologies de gestió de treballs i de contenidors de codi obert, s'han desenvolupat ferramentes i components de codi obert, i s'han implementat receptes per a la configuració automatitzada de les distintes arquitectures dissenyades des de la perspectiva DevOps. / [EN] Scientific applications generally imply a variable and an unpredictable computational workload that institutions must address by dynamically adjusting the allocation of resources to their different computational needs. Scientific applications could require a high capacity, e.g. the concurrent usage of computational resources for processing several independent jobs (High Throughput Computing or HTC) or a high capability by means of using high-performance resources for solving complex problems (High Performance Computing or HPC). The computational resources required in this type of applications usually have a very high cost that may exceed the availability of the institution's resources or they are may not be successfully adapted to the scientific applications, especially in the case of infrastructures prepared for the execution of HPC applications. Indeed, it is possible that the different parts that compose an application require different type of computational resources. Nowadays, cloud service platforms have become an efficient solution to meet the need of HTC applications as they provide a wide range of computing resources accessible on demand. For this reason, the number of hybrid computational infrastructures has increased during the last years. The hybrid computation infrastructures are the combination of infrastructures hosted in cloud platforms and the computation resources hosted in the institutions, which are named on-premise infrastructures. As scientific applications can be processed on different infrastructures, the application delivery has become a key issue. Nowadays, containers are probably the most popular technology for application delivery as they ease reproducibility, traceability, versioning, isolation, and portability. The main objective of this thesis is to provide an architecture and a set of services to build up hybrid processing infrastructures that fit the need of different workloads. Hence, the thesis considered aspects such as elasticity and federation. The use of vertical and horizontal elasticity by developing a proof of concept to provide vertical elasticity on top of an elastic cloud architecture for data analytics. Afterwards, an elastic cloud architecture comprising heterogeneous computational resources has been implemented for medical imaging processing using multiple processing queues for jobs with different requirements. The development of this architecture has been framed in a collaboration with a company called QUIBIM. In the last part of the thesis, the previous work has been evolved to design and implement an elastic, multi-site and multi-tenant cloud architecture for medical image processing has been designed in the framework of a European project PRIMAGE. This architecture uses a storage integrating external services for the authentication and authorization based on OpenID Connect (OIDC). The tool kube-authorizer has been developed to provide access control to the resources of the processing infrastructure in an automatic way from the information obtained in the authentication process, by creating policies and roles. Finally, another tool, hpc-connector, has been developed to enable the integration of HPC processing infrastructures into cloud infrastructures without requiring modifications in both infrastructures, cloud and HPC. It should be noted that, during the realization of this thesis, different contributions to open source container and job management technologies have been performed by developing open source tools and components and configuration recipes for the automated configuration of the different architectures designed from the DevOps perspective. The results obtained support the feasibility of the vertical elasticity combined with the horizontal elasticity to implement QoS policies based on a deadline, as well as the feasibility of the federated authentication model to combine public and on-premise clouds. / López Huguet, S. (2021). Elastic, Interoperable and Container-based Cloud Infrastructures for High Performance Computing [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172327 / TESIS / Compendio

This thesis is focused on the analysis and comparison of rental apartments in Prostejov and all the factors that have the level of rents in the area of influence. The work presents textual and graphical part of a designated location according to the amount of rent in various parts of the city Prostejov flats of sizes 1 + 1, 1 + KK, 2 + 1, 2 + KK, 3 + 1, 3 + KK. These dispositions are examined and appreciation is shown in tables and graphs. The result is a calculation and comparison of individual dispositions rent flats and assess the factors that have influence on the price.

A large amount of today's communication occurs within data centers where a large number of virtual servers (running one or more virtual machines) provide service providers with the infrastructure needed for their applications and services. In this thesis, we will look at the next step in the virtualization revolution, the virtualized network. Software-defined networking (SDN) is a relatively new concept that is moving the field towards a more software-based solution to networking. Today when a packet is forwarded through a network of routers, decisions are made at each router as to which router is the next hop destination for the packet. With SDN these decisions are made by a centralized SDN controller that decides upon the best path and instructs the devices along this path as to what action each should perform. Taking SDN to its extreme minimizes the physical network components and increases the number of virtualized components. The reasons behind this trend are several, although the most prominent are simplified processing and network administration, a greater degree of automation, increased flexibility, and shorter provisioning times. This in turn leads to a reduction in operating expenditures and capital expenditures for data center owners, which both drive the further development of this technology. Virtualization has been gaining ground in the last decade. However, the initial introduction of virtualization began in the 1970s with server virtualization offering the ability to create several virtual server instances on one physical server. Today we already have taken small steps towards a virtualized network by virtualization of network equipment such as switches, routers, and firewalls. Common to virtualization is that it is in early stages all of the technologies have encountered trust issues and general concerns related to whether software-based solutions are as rugged and reliable as hardwarebased solutions. SDN has also encountered these issues, and discussion of these issues continues among both believers and skeptics. Concerns about trust remain a problem for the growing number of cloud-based services where multitenant deployments may lead to loss of personal integrity and other security risks. As a relatively new technology, SDN is still immature and has a number of vulnerabilities. As with most software-based solutions, the potential for security risks increases. This thesis investigates how denial-of-service (DoS) attacks affect an SDN environment and a singlethreaded controller, described by text and via simulations. The results of our investigations concerning trust in a multi-tenancy environment in SDN suggest that standardization and clear service level agreements are necessary to consolidate customers’ confidence. Attracting small groups of customers to participate in user cases in the initial stages of implementation can generate valuable support for a broader implementation of SDN in the underlying infrastructure. With regard to denial-of-service attacks, our conclusion is that hackers can by target the centralized SDN controller, thus negatively affect most of the network infrastructure (because the entire infrastructure directly depends upon a functioning SDN controller). SDN introduces new vulnerabilities, which is natural as SDN is a relatively new technology. Therefore, SDN needs to be thoroughly tested and examined before making a widespread deployment. / Dagens kommunikation sker till stor del via serverhallar där till stor grad virtualiserade servermiljöer förser serviceleverantörer med infrastukturen som krävs för att driva dess applikationer och tjänster. I vårt arbete kommer vi titta på nästa steg i denna virtualiseringsrevolution, den om virtualiserade nätverk. mjukvarudefinierat nätverk (eng. Software-defined network, eller SDN) kallas detta förhållandevis nya begrepp som syftar till mjukvarubaserade nätverk. När ett paket idag transporteras genom ett nätverk tas beslut lokalt vid varje router vilken router som är nästa destination för paketet, skillnaden i ett SDN nätverk är att besluten istället tas utifrån ett fågelperspektiv där den bästa vägen beslutas i en centraliserad mjukvaruprocess med överblick över hela nätverket och inte bara tom nästa router, denna process är även kallad SDN kontroll. Drar man uttrycket SDN till sin spets handlar det om att ersätta befintlig nätverksutrustning med virtualiserade dito. Anledningen till stegen mot denna utveckling är flera, de mest framträdande torde vara; förenklade processer samt nätverksadministration, större grad av automation, ökad flexibilitet och kortare provisionstider. Detta i sin tur leder till en sänkning av löpande kostnader samt anläggningskostnader för serverhallsinnehavare, något som driver på utvecklingen. Virtualisering har sedan början på 2000-talet varit på stark frammarsch, det började med servervirtualisering och förmågan att skapa flertalet virtualiserade servrar på en fysisk server. Idag har vi virtualisering av nätverksutrustning, såsom switchar, routrar och brandväggar. Gemensamt för all denna utveckling är att den har i tidigt stadie stött på förtroendefrågor och överlag problem kopplade till huruvida mjukvarubaserade lösningar är likvärdigt robusta och pålitliga som traditionella hårdvarubaserade lösningar. Detta problem är även något som SDN stött på och det diskuteras idag flitigt bland förespråkare och skeptiker. Dessa förtroendefrågor går på tvären mot det ökande antalet molnbaserade tjänster, typiska tjänster där säkerheten och den personliga integriten är vital. Vidare räknar man med att SDN, liksom annan ny teknik medför vissa barnsjukdomar såsom kryphål i säkerheten. Vi kommer i detta arbete att undersöka hur överbelastningsattacker (eng. Denial-of-Service, eller DoS-attacker) påverkar en SDN miljö och en singel-trådig kontroller, i text och genom simulering. Resultatet av våra undersökningar i ämnet SDN i en multitenans miljö är att standardisering och tydliga servicenivåavtal behövs för att befästa förtroendet bland kunder. Att attrahera kunder för att delta i mindre användningsfall (eng. user cases) i ett inledningsskede är också värdefullt i argumenteringen för en bredare implementering av SDN i underliggande infrastruktur. Vad gäller DoS-attacker kom vi fram till att det som hackare går att manipulera en SDN infrastruktur på ett sätt som inte är möjligt med dagens lösningar. Till exempel riktade attacker mot den centraliserade SDN kontrollen, slår man denna kontroll ur funktion påverkas stora delar av infrastrukturen eftersom de är i ett direkt beroende av en fungerande SDN kontroll. I och med att SDN är en ny teknik så öppnas också upp nya möjligheter för angrepp, med det i åtanke är det viktigt att SDN genomgår rigorösa tester innan större implementation.