No / The growth of wireless devices affects the availability of limited frequencies or spectrum bands as it has been known that spectrum bands are a natural resource that cannot be added. Meanwhile, the licensed frequencies are idle most of the time. Cognitive radio is one of the solutions to solve those problems. Cognitive radio is a promising technology that allows the unlicensed users known as secondary users (SUs) to access licensed bands without making interference to licensed users or primary users (PUs). As cloud computing has become popular in recent years, cognitive radio networks (CRNs) can be integrated with cloud platform. One of the important issues in CRNs is security. It becomes a problem since CRNs use radio frequencies as a medium for transmitting and CRNs share the same issues with wireless communication systems. Another critical issue in CRNs is performance. Security has adverse effect to performance and there are trade-offs between them. The goal of this paper is to investigate the performance related to security trade-off in CRNs with supporting cloud platforms. Furthermore, Queuing Network Models with preemptive resume and preemptive repeat identical priority are applied in this project to measure the impact of security to performance in CRNs with or without cloud platform. The generalized exponential (GE) type distribution is used to reflect the bursty inter-arrival and service times at the servers. The results show that the best performance is obtained when security is disabled and cloud platform is enabled.

IoT (Internet of Things) systems implement event-driven architectures that are deployed on an ever-increasing scale as more and more devices (things) become connected to the internet. Consequently, IoT cloud platforms are becoming increasingly distributed and complex as they adapt to handle larger amounts of user requests and device data. The complexity of such systems makes it close to impossible to predict how they will handle failures that inevitably occur once they are put into production. Chaos engineering, the practice of deliberately injecting faults in production, has successfully been used by many software companies as a means to build confidence in that their complex systems are reliable for the end-users. Nevertheless, its applications in the scope of IoT systems remain largely unexplored in research. Modern IoT cloud platforms are built cloud native with containerized microservices, container orchestration, and other cloud native technologies, much like any other distributed cloud computing system. We therefore investigate cloud native chaos engineering technology and its applications in IoT cloud platforms. We also introduce a framework for getting started with using cloud native chaos engineering to verify and improve the resilience of IoT systems and evaluate it through a case study at a commercial home appliance manufacturer. The evaluation successfully reveals unknown system behavior and results in the discovery of potential resilience improvements for the case study IoT system. The evaluation also shows three ways to measure the resilience of IoT cloud platforms with respect to perturbations, these are: (1) success rate of user requests, (2) system health, and (3) event traffic. / IoT(Sakernas Internet)-system implementerar händelsedrivna arkitekturer som driftsätts i allt större skala i och med att allt fler enheter (saker) blir anslutna till internet. IoT-molnplattformar blir därmed alltmer distribuerade och komplexa i takt med att de anpassas till att hantera större mängder användarförfrågningar och enhetsdata. Komplexiteten hos sådana system gör det nära omöjligt att förutsäga hur de hanterar problem som oundvikligen inträffar när de väl körs i produktionsmiljö. Kaosteknik, att avsiktligt injicera fel medans ett system körs i produktionsmiljön, har framgångsrikt använts av många mjukvaruföretag som ett sätt att bygga förtroende för att deras komplexa system är tillförlitliga för slutanvändarna. Trots det är dess tillämpningar inom ramen för IoT-system i stort sett outforskade inom dataforskning. Moderna IoT-molnplattformar byggs molnäkta med containeriserade mikrotjänster, containerorkestering, och andra molnäkta teknologier, precis som andra distribuerade molntjänstsystem. Vi undersöker därför molnäkta kaosteknik och dess tillämpningar i IoT-molnplattformar. Vi introducerar även ett ramverk för att komma igång med att använda molnäkta kaosteknik för att verifiera och förbättra motståndskraften hos IoT-system och utvärderar det genom en fallstudie hos en kommersiell tillverkare av hushållsapparater. Utvärderingen lyckas avslöja okänt systembeteende och resulterar i upptäckten av potentiella motståndskraftsförbättringar för IoT-systemet i fallstudien. Utvärderingen visar också tre sätt att mäta motståndskraften hos IoT-molnplattformar med hänsyn till störningar, dessa är: (1) andel framgångsrika användarförfrågningar, (2) systemhälsa och (3) händelsetrafik.

Yes / There is increasing evidence that the Cloud Computing services have become a strategic direction for governments' IT work by the dawn of the third-millennium. The inevitability of this computing technology has been recognized not only in the developed countries like the UK, USA and Japan, but also in the developing countries like the Middle East region and Malaysia, who have launched migrations towards Cloud platforms for more flexible, open, and collaborative public services. In Jordan, the cloud-based e-government project has been deemed as one of the high priority areas for the government agencies. In spite of its phenomenal evolution, various governmental cloud-based services still facing adoption challenges of e-government projects like technological, human-aspects, social, and financial which need to be treated and considered carefully by any government agency contemplating its implementation. While there have been extensive efforts to investigate the e-government adoption from the citizens' perspective using different theories and models, none have paid adequate attention to the security issues. This paper explores the different perspectives of the extent in which these challenges inhibit the acceptance and use of cloud computing in Jordanian public sector. In addition to examining the effect of these challenges on the participants’ security perception. The empirical evidence provided a total of 220 valid responses to our online questionnaire from Jordanian citizens including IT- staff from different government sectors. Based on the data analysis some significant challenges were identified. The results can help the policy makers in the public sector to guide successful acceptance and adoption of cloud-based e-government services in Jordan. / Mutah University - Jordan

Cloud computing is a computing paradigm where large numbers of devices are connected through networks that provide a dynamically scalable infrastructure for applications, data and storage. Currently, many businesses, from small scale to big companies and industries, are changing their operations to utilize cloud services because cloud platforms could increase company’s growth through process efficiency and reduction in information technology spending [Coles16]. Companies are relying on cloud platforms like Amazon Web Services, Google Compute Engine, and Microsoft Azure, etc., for their business development. Due to the emergence of new technologies, devices, and communications, the amount of data produced is growing rapidly every day. Big data is a collection of large dataset, typically hundreds of gigabytes, terabytes or petabytes. Big data storage and the analytics of this huge volume of data are a great challenge for companies and new businesses to handle, which is a primary focus of this paper. This research was conducted on Amazon’s Elastic Compute Cloud (EC2) and Microsoft Azure platforms using the HiBench Hadoop Big Data Benchmark suite [HiBench16]. Processing huge volumes of data is a tedious task that is normally handled through traditional database servers. In contrast, Hadoop is a powerful framework is used to handle applications with big data requirements efficiently by using the MapReduce algorithm to run them on systems with many commodity hardware nodes. Hadoop’s distributed file system facilitates rapid storage and data transfer rates of big data among the nodes and remains operational even when a node failure has occurred in a cluster. HiBench is a big data benchmarking tool that is used for evaluating the performance of big data applications whose data are handled and controlled by the Hadoop framework cluster. Hadoop cluster environment was enabled and evaluated on two cloud platforms. A quantitative comparison was performed on Amazon EC2 and Microsoft Azure along with a study of their pricing models. Measures are suggested for future studies and research.

Enterprise Database Management Systems (DBMSs) have to contend with resource-intensive and time-varying workloads, making them well-suited candidates for migration to cloud plat-forms { specifically, they can dynamically leverage the resource elasticity while retaining affordability through the pay-as-you-go rental interface. The current design of database engine components lays emphasis on maximizing computing efficiency, but to fully capitalize on the cloud's benefits, the outlays of these computations also need to be factored into the planning exercise. In this thesis, we investigate this contemporary problem in the context of industrial-strength deployments of relational database systems on real-world cloud platforms. Specifically, we consider how the traditional metric used to compare query execution plans, namely response-time, can be augmented to incorporate monetary costs in the decision process. The challenge here is that execution-time and monetary costs are adversarial metrics, with a decrease in one entailing a rise in the other. For instance, a Virtual Machine (VM) with rich physical resources (RAM, cores, etc.) decreases the query response-time, but is expensive with regard to rental rates. In a nutshell, there is a tradeoff between money and time, and our goal therefore is to identify the VM that others the best tradeoff between these two competing considerations. In our study, we pro le the behavior of money versus time for a given query, and de ne the best tradeoff as the \knee" { that is, the location on the pro le with the minimum Euclidean distance from the origin. To study the performance of industrial-strength database engines on real-world cloud infrastructure, we have deployed a commercial DBMS on Google cloud services. On this platform, we have carried out extensive experimentation with the TPC-DS decision-support benchmark, an industry-wide standard for evaluating database system performance. Our experiments demonstrate that the choice of VM for hosting the database server is a crucial decision, because: (i) variation in time and money across VMs is significant for a given query, (ii) no one VM offers the best money-time tradeoff across all queries. To efficiently identify the VM with the best tradeoff from a large suite of available configurations, we propose a technique to characterize the money-time pro le for a given query. The core of this technique is a VM pruning mechanism that exploits the property of partially ordered set of the VMs on their resources. It processes the minimal and maximal VMs of this poset for estimated query response-time. If the response-times on these extreme VMs are similar, then all the VMs sandwiched between them are pruned from further consideration. Otherwise, the already processed VMs are set aside, and the minimal and maximal VMs of the remaining unprocessed VMs are evaluated for their response-times. Finally, the knee VM is identified from the processed VMs as the one with the minimum Euclidean distance from the origin on the money-time space. We theoretically prove that this technique always identifies the knee VM; further, if it is acceptable to and a \near-optimal" knee by providing a relaxation-factor on the response-time distance from the optimal knee, then it is also capable of finding more efficiently a satisfactory knee under these relaxed conditions. We propose two favors of this approach: the first one prunes the VMs using complete plan information received from database engine API, and named as Plan-based Identification of Knee (PIK). On the other hand, to further increase the efficiency of the identification of the knee VM, we propose a sub-plan based pruning algorithm called Sub-Plan-based Identification of Knee (SPIK), which requires modifications in the query optimizer. We have evaluated PIK on a commercial system and found that it often requires processing for only 20% of the total VMs. The efficiency of the algorithm is further increased significantly, by using 10-20% relaxation in response-time. For evaluating SPIK , we prototyped it on an open-source engine { Postgresql 9.3, and also implemented it as Java wrapper program with the commercial engine. Experimentally, the processing done by SPIK is found to be only 40% of the PIK approach. Therefore, from an overall perspective, this thesis facilitates the desired migration of enterprise databases to cloud platforms, by identifying the VM(s) that offer competitive tradeoffs between money and time for the given query.