There are high demands of effective and high-performance of collaborations between mobile devices in the places where traditional Internet connections are unavailable, unreliable, or significantly overburdened, such as on a battlefield, disaster zones, isolated rural areas, or crowded public venues. To enable collaboration among the devices in opportunistic networks, code offloading and Remote Method Invocation are the two major mechanisms to ensure code portions of applications are successfully transmitted to and executed on the remote platforms. Although these domains are highly enjoyed in research for a decade, the limitations of multi-device connectivity, system error handling or cross platform compatibility prohibit these technologies from being broadly applied in the mobile industry. To address the above problems, we designed and developed UMSEF - an Universal Mobile Service Execution Framework, which is an innovative and radical approach for mobile computing in opportunistic networks. Our solution is built as a component-based mobile middleware architecture that is flexible and adaptive with multiple network topologies, tolerant for network errors and compatible for multiple platforms. We provided an effective algorithm to estimate the resource availability of a device for higher performance and energy consumption and a novel platform for mobile remote method invocation based on declarative annotations over multi-group device networks. The experiments in reality exposes our approach not only achieve the better performance and energy consumption, but can be extended to large-scaled ubiquitous or IoT systems.

This study compares the performance of two popular cross-platform mobile application development frameworks, Flutter and React Native. As the number of mobile users continues to grow, the ability to target multiple platforms using a single codebase is increasingly important for developers and companies. We conducted three manual UI tests; scrolling through a list, testing the camera, and filtering a large dataset to measure the performance of the frameworks in terms of CPU usage, memory usage, and janky frames on an Android device. The results indicate that Flutter may provide better performance in specific situations when compared to React Native. The study contributes to the existing research by providing additional insights into the performance of these frameworks under specific test scenarios.

Background: In today's digital world, there is increasing importance on cross-platform performance testing and the challenges faced by businesses in achieving efficient performance for applications across multiple platforms. Predictive models, such as machine learning and regression, have emerged as potential solutions to predict performance to be quickly analyzed, thus eliminating the need to execute an entire environment. Predicting performance can help firms save time and resources to keep pace with market demand, but potential risks and limitations need to be considered. With the increasing availability of data, predictive models have become effective problem-solving methods in various industries, including the testing industry. Objectives: This research aims to investigate the economic consequences and opportunities of implementing predictive models to predict cross-platform performance for firms operating in the software market and evaluate the performance of three models when predicting cross-platform performance. The study aims to add arguments to help businesses make informed decisions on the adoption of predictive models. Methods: The methodology employed in this research involved evaluating Multiple Linear Regression, Multiple Neural Network, and Random Forest, to gain insight into how such models perform when predicting performance. In addition to this analysis, interviews were conducted with industry experts to get an understanding of current processes and the potential benefits of adopting predictive models to identify the economic consequences of implementing such models. Results: The result shows that Multiple Linear Regression was the most promising one, with an R2 value of 0.79. Additionally, the research revealed that the current testing process faces difficulties when testing on multiple platforms. While predicting performance can provide cost and time savings, challenges and risks, such as data privacy and model trust, must also be considered. Conclusions: Multiple Linear Regression exhibited the most favorable performance among the evaluated models, with consistent results across all test runs and indicating a linear relationship. The economic consequences identified were the continuously required maintenance and updates of predictive models to remain accurate throughout the lifecycle. This implies ongoing costs, such as the complexity and cost of generating and storing the necessary data to train the models. Thus, the adoption of predictive models is still in its early stages, and while there are significant benefits, there are also challenges to address.

When developing mobile apps, multiple factors must be considered when choosing between native or cross-platform technologies. The latter offers deployment of one codebase to multiple operating systems, such as Android and iOS. However, we argue that common design techniques lack an understanding of specific needs that separate iOS and Android users. This work presents an experimental approach using UI prototypes and existing native iOS and Android mobile applications to identify issues in usability of the two systems. We conduct a large amount of usability tests involving 34 participants and find that our prototypes and apps that follow Apple’s Human Interface Guidelines are easier to use in terms of one primary usability metric, notably task time, with a statistically significant difference between iOS and Android testers in two out of four tests. On this basis we investigate what key UI elements and design patterns cause disruptions in otherwise smooth User Experiences. Alongside documenting those, we also list key elements that influence the usability on a more general level. We provide suggestions to app designers and developers on avoiding designs that are considered producing usability issues by at least one of the two groups of iOS and Android users and on design patterns to improve the User Experience.

The number of social media platforms (SMP hereinafter) is ever-increasing, and all of these platforms compete for more attention and content. The global social media market is expected to grow to $223.11 billion in 2022 (Social Media Global Market Report, 2022). In an era characterized by the meteoric rise and evolution of Social Media Platforms (SMPs), understanding the interplay between platform features and user behaviors is both critical and complex. In this dissertation, we aim to elucidate the relationship between SMPs and society, with the ultimate objective of fostering a healthier social media ecosystem. This dissertation is comprised of two incisive essays, both of which are underpinned by robust theoretical frameworks. The first essay adopts an expansive purview of the SMP ecosystem. Grounded in Uses and Gratifications Theory and media studies, it establishes a user typology based on the previous typologies and examines the interaction between user motives, SMP scores, and SMP features. Employing the Analytic Hierarchy Process, a sophisticated decision-making tool, the study quantifies utility-driven choices across platforms. A notable revelation is the heterogeneity in user reliance on SMP features, contingent upon their underlying motives. This essay offers critical insights into the multifaceted nature of SMP utilization. The second essay focuses specifically on Reddit's ChangeMyView community, an exemplar of constructive discourse in the SMP environment. It constructs a theoretical model premised on the Elaboration Likelihood Model and the concept of pre-suasion, and utilizes a mixed-methods approach to explore the persuasive strategies using Content Analysis. We also utilize ChatGPT in the Content Analysis to corroborate our inferences. The findings confirm our theorization about the role of the Delta reward system in fostering reflective engagement with content, which leads to informed opinion formation. Collectively, with these essays, we aim to provide extensive insights into the dynamic interplay between SMPs and users. Both essays hold significant implications for research community, SMP decision-makers, organizations that use SMPs, and a broader audience interested in optimizing their social media repertoire. Through a theory-driven and empirical lens, employing several epistemologies, this dissertation provides a holistic depiction of the SMP ecosystem. / Doctor of Philosophy / The landscape of social media is constantly evolving with an ever-growing number of platforms vying for user attention. In this dissertation, we aim to analyze the relationship between social media platforms and their users, seeking ways to foster a healthier and more constructive social media environment. This dissertation is structured into two distinct yet interconnected essays. In the first essay, we look at the broader ecosystem of social media platforms. It categorizes users based on their motivations for using social media, such as seeking information or connecting with others. We examine how different features of social media platforms cater to these diverse motivations. To accomplish this, we employ a method known as the Analytic Hierarchy Process, which is a decision-making tool used to measure and analyze choices. The key insight from this essay is the diversity in how users interact with social media features, and how this interaction is influenced by their underlying motivations. In the second essay, we take a closer look at a specific community on Reddit called ChangeMyView. This community is unique as it encourages users to engage in thoughtful and reasoned debates. In this essay, we develop a theoretical model to understand the mechanisms through which information is processed and opinions are changed within this community with a strong focus on Delta system, a feature that rewards users for successfully changing someone's opinion through challenging their view and pointing the flaws in their thinking. Collectively, the dissertation provides an in-depth understanding of the dynamic relationship between social media platforms and users. It does so through rigorous analysis underpinned by theoretical frameworks. This research is not only academically significant but also has practical implications. It provides valuable insights for decision-makers to improve social media platforms, aids organizations in understanding how best to engage with social media, and informs users on optimizing their social media interactions. In essence, this dissertation serves as a comprehensive analysis that bridges the gap between the ever-evolving features of social media platforms and the multifaceted behaviors of their users.

Mobile applications are a critical part of everyday life. Animations in mobile applications demand optimized performance, which developers are persistently striving to achieve. This study examines the performance of mobile applications developed using native approaches for iOS and Android, as well as the Flutter framework for cross-platform approach, while executing animations. This was motivated by the fact that while cross-platform development offers advantages in terms of development efficiency, it often results in decreased performance. Since the field of mobile development is continuously evolving, it is important to explore new capabilities of mobile technologies. The purpose of this study is to understand the differences in CPU and RAM usage between native and cross-platform applications by examining two types of animation implementations, thereby aiming to identify the causes of the performance gap and propose solutions to decrease the performance gap. This study involved experiments, a literature study and an analysis of the results to address the research questions and fulfill the purpose. The findings of this study showed that the cross-platform approach resulted in higher CPU and RAM usage than the native approaches. However, the performance gap was less noticeable in one of the animation implementations. Thus indicating that the performance of mobile applications can be significantly influenced by the choice of animation implementation. Therefore, a strategic approach to mitigating the performance gap could involve careful selection of Flutter widgets or the incorporation of efficient libraries.

This thesis examines the implementation of an Always On VPN solution for Windows 10 and macOS, focusing on the configuration of a Palo Alto Firewall to enable their GlobalProtect VPN as Always On. This means that the VPN solution is enabled on a device at all times. The primary objective of this thesis is to present a solution, where the GlobalProtect VPN is configured to be Always On for both Windows 10 and macOS devices. Furthermore, the objective is to evaluate the performance impact of the VPN solution on network throughput, packet loss, and jitter. The study compares performance in both AES 128-bit GCM and AES 256-bit GCM encryption modes, as well as performance without the VPN, to determine its potential impact on employee workflow. The employee workflow consists of file uploads of varying sizes across a single stream as well as multiple streams. Here, our study finds that performance is reduced with the VPN solution active and can limit upload speeds by up to 45% depending on the tested scenario. Jitter and packet loss can also increase by more than 50% for jitter and roughly 10% for packet loss. It is worth noting that the practical differences such as time lost through lower network throughput when enabling the VPN solution or added jitter and packet loss is till very low for the majoirty of the scenarios tested in this thesis.  Additionally, the thesis analyzes the functional and performance differences between Windows 10 and macOS when utilizing the VPN solution. Performance wise, the loss is similar between Windows 10 and macOS in certain scenarios but can differ in others. The thesis also highlights a significant limitation of the GlobalProtect VPN, specifically concerning its ability to enforce an Always On VPN experience on macOS devices. Unlike Windows 10, macOS users can still uninstall the VPN agent, posing challenges in ensuring continuous VPN connectivity. The thesis proposes removing administrative rights from macOS users as an optimal solution to prevent agent uninstallation and to maintain an Always On VPN experience with Palo Alto's GlobalProtect VPN.

Mobile application development has grown in the past few years, and instead of native development, some developers have moved to a new strategy; cross-platform mobile development using frameworks. There are many frameworks that all have their use case, but whether or not these frameworks are ready to be used in production applications is hard to decide on . This research aims to find the strengths and weaknesses of cross-platform mobile development frameworks, and how they can be improved to better suit the needs of developers. To gather data in this topic a survey was created to analyze developer experiences on frameworks in key areas such as front-end design, platform maturity and more. The results reveal that there are many areas that can be improved, but frameworks are a great tool for smaller teams and are being used extensively already to create applications for multiple platforms.

Idag finns det många olika metoder för att bygga appar. Det är möjligt att utveckla separata appar för samtliga plattformar eller att använda något av Cross Platform-ramverken. Då de olika metoderna har både för- och nackdelar är det av vikt att välja den bästa metoden för just sin app. Under detta arbete kommer en app att skapas med två olika metoder. En med Cross Platform-ramverket React Native samt en motsvarande webbaserad app, närmare bestämt en Progressiv Webb App (PWA) skriven i React. Därefter kommer en jämförelse av tre funktionaliteter (kamera, bluetooth-skanning och NFC-skanning) att utföras för att besluta vilken av dessa appar som gav det bästa resultatet samt arbetsbördan ur ett utvecklarperspektiv. De främsta problemen som uppstod var stylingproblem, kamerafunktionalitet samt att vissa webbmotorer inte tillåter bluetooth- och NFC-skanning. Detta innebar att dessa funktionaliteter inte fungerar på alla webbläsare. Resultatet indikerar att PWA har sina begränsningar när det kommer till hårdvarunära funktionalitet, men är i övrigt ett mycket bra sätt att bygga en app på. React Native är bättre när det kommer till hårdvarunära funktioner men kan leda till fler stylingproblem. / There are many different ways to create apps these days, one can choose to create separate apps for each platform or use a Cross Platform framework. Because different methods have different benefits and drawbacks, it is critical to find the best method for your specific app. This project will result in the development of two apps: a Cross Platform React Native app and a web-based app, dubbed a Progressive Web App (PWA) written in React. Following that, a comparison of three functions (camera, bluetooth scanning, and NFC scanning) will be carried out in order to determine which of these frameworks provided the best results and workload from an engineering perspective. The most serious issues that arose were styling issues, camera functionality, and the fact that some web browser engines do not support Bluetooth or NFC scanning, implying that these features do not work on all browsers. PWA has its limitations when it comes to native features, but it is still a very good way of building an app. When it comes to native features, React Native is better, but it can lead to more stylistic issues.

I denna studie kommer vi att undersöka det populära ramverket Xamarin. Xamarin är ett cross-platform ramverk som använder programmeringsspråket C# för att utveckla samma applikation för iOS, Android och Windows Phone. Studiens huvudsyfte är att genomföra en inledande explorativ studie där vi försöker att identifiera ett antal särskiljande aspekter mellan native- och Xamarin utveckling och dess slutprodukter.För att göra denna jämförelse har vi utvecklat tre applikationer: en native android applikation, en Windows Phone applikation i Xamarin, och en Android app-likation i Xamarin. Med hjälp av en litteraturstudie och utvecklingen av de ovan-nämnda applikationerna har de särskiljande aspekter observerats och identifieras.Resultatet av vår studie visar att native Android applikationen tar upp mindre plats i telefonen jämfört med Xamarin Android applikationen, medan Xamarin Win-dows Phone applikationen tar 1/6 mindre utrymme i telefonen jämfört med Xamarin Android applikationen. Ytterligare tester visar också att Xamarin Android appli-kationen tar längre tid att starta jämfört med native Android och Xamarin Winows Phone applikationen. / In this study, we will examine the popular framework Xamarin. Xamarin is a cross-platform framework that uses the C# programming language to develop the same application for iOS, Android and Windows Phone. The study's main purpose is to conduct an initial exploratory study in which we try to identify a number of distin-guishing aspects between native- and Xamarin development and its products. In order to make this comparison we developed three applications: one native android application, one Windows Phone application in Xamarin, and one Android application in Xamarin. With the help of a literature study and the development of the aforementioned applications, the distinctive aspects have been observed and identified.The result of our study shows that the native android application takes up less space in the phone compared to the Xamarin android application, whereas the Xamarin Windows Phone app takes 1/6 less space in the phone compared to the Xamarin android application. Further tests also show that the Xamarin android ap¬p-lication takes longer time to start-up than with the native Android and Xamarin Winows Phone applications.