The thin-client/server computing model mandates applications running solely on a server and client devices connecting to the server through the Internet for carrying out works. Traditional thin-client/server computing model comprises only a single server and works only within LAN environment, which severely restrict its applicability. To meet the demand of reasonable response time over WAN, a modified thin-client/server computing model, MAS TC/S, was proposed. In MAS TC/S, multiple application servers spreading over WAN are installed, and each client device can freely connect to any application server that is close to it. However, reducing delay associated with fetching absent files, which are stored in other servers, is a challenging issue in MAS TC/S. We propose to employ data prefetching mechanisms to speed up file fetching. We use the suffix tree-like structure to store users¡¦ previous file access records and define two temporal relationships between two records: followed by or concurrent with, to decide the set of files that should be prefetched together. Each file access subsequence is associated with a set of predicted file sets, each carrying a different weight. Given a current file access session, we will first find a matching file access subsequence and then choose the predicted set that has the highest weight. Based on the chosen predicted set, suitable files are prefeteched to the connected server. We compare our method with All-Kth-Order Markov model and find our method gets higher hit ratio under various operating regions.

Today, thin client applications often rely on the infrastructure of the WWW to deliver their user interfaces (UIs) to clients. While this approach does not require the deployment of application logic on the client, web-based UIs typically do not provide the same level of usability as window-based UIs. We therefore present a UI framework that combines the flexibility of a thin presentation logic with the usability of a full-featured UI: Our approach uses an XMPP-based instant messaging infrastructure to exchange XUL interface descriptions and events between the application logic on the server and a generic UI rendering engine on the client.

This diploma thesis is devoted to a modern attitude of desktop computer usage, that uses operating system and applications virtualization. The paper describes theoretical principles of virtualization techniques and selection of the proper solution for the organization. Diploma thesis also describes the project implementation.

This research investigates the applicability of thin client in a hospital environment. First, a set of thin client application criteria in terms of hardware, function characteristics, network, and application platform are identified. Second, we analyze the healthcare delivery process in terms of operation process, hardware, and application platform. Third, we evaluate the fitness of thin client application by matching the above two sets of criteria. A case study was conducted to valid the applicability of this approach. These results provide great insight for practitioners and scholars for enhancing their understanding of thin client implementation and provide implication guidelines to help practitioners adapt thin client in health care industry.

abstract: The Web is one of the most exciting and dynamic areas of development in today’s technology. However, with such activity, innovation, and ubiquity have come a set of new challenges for digital forensic examiners, making their jobs even more difficult. For examiners to become as effective with evidence from the Web as they currently are with more traditional evidence, they need (1) methods that guide them to know how to approach this new type of evidence and (2) tools that accommodate web environments’ unique characteristics. In this dissertation, I present my research to alleviate the difficulties forensic examiners currently face with respect to evidence originating from web environments. First, I introduce a framework for web environment forensics, which elaborates on and addresses the key challenges examiners face and outlines a method for how to approach web-based evidence. Next, I describe my work to identify extensions installed on encrypted web thin clients using only a sound understanding of these systems’ inner workings and the metadata of the encrypted files. Finally, I discuss my approach to reconstructing the timeline of events on encrypted web thin clients by using service provider APIs as a proxy for directly analyzing the device. In each of these research areas, I also introduce structured formats that I customized to accommodate the unique features of the evidence sources while also facilitating tool interoperability and information sharing. / Dissertation/Thesis / Doctoral Dissertation Computer Science 2017

The aim of the theoretical part is a summary of commonly used graphics components for developing web applications in Java. In the introduction, theoretical part contains basic principles and terms related to the topic of work. Below is an overview of components, which is based mostly on documentation most widely used frameworks for building web applications. Individual components are divided into groups and there are descriptions and alternative names for each of them. Description of each component is aimed at its appearance as well as at routine use in practice. The practical part results from the list of components and categories created in the theoretical part. The first part is a description of the framework and its fundamental principles, especially creation of components. Each category and the components identified in the theoretical part are analyzed from the perspective of their applications in the Wicket framework. In the case of non-existing components in the framework are given options and mechanisms that replace the functionality of missing components.

No description available.

A vast number of online services is based on users contributing their personal information. Examples are manifold, including social networks, electronic commerce, sharing websites, lodging platforms, and genealogy. In all cases user privacy depends on a collective trust upon all involved intermediaries, like service providers, operators, administrators or even help desk staff. A single adversarial party in the whole chain of trust voids user privacy. Even more, the number of intermediaries is ever growing. Thus, user privacy must be preserved at every time and stage, independent of the intrinsic goals any involved party. Furthermore, next to these new services, traditional offline analytic systems are replaced by online services run in large data centers. Centralized processing of electronic medical records, genomic data or other health-related information is anticipated due to advances in medical research, better analytic results based on large amounts of medical information and lowered costs. In these scenarios privacy is of utmost concern due to the large amount of personal information contained within the centralized data. We focus on the challenge of privacy-preserving processing on genomic data, specifically comparing genomic sequences. The problem that arises is how to efficiently compare private sequences of two parties while preserving confidentiality of the compared data. It follows that the privacy of the data owner must be preserved, which means that as little information as possible must be leaked to any party participating in the comparison. Leakage can happen at several points during a comparison. The secured inputs for the comparing party might leak some information about the original input, or the output might leak information about the inputs. In the latter case, results of several comparisons can be combined to infer information about the confidential input of the party under observation. Genomic sequences serve as a use-case, but the proposed solutions are more general and can be applied to the generic field of privacy-preserving comparison of sequences. The solution should be efficient such that performing a comparison yields runtimes linear in the length of the input sequences and thus producing acceptable costs for a typical use-case. To tackle the problem of efficient, privacy-preserving sequence comparisons, we propose a framework consisting of three main parts. a) The basic protocol presents an efficient sequence comparison algorithm, which transforms a sequence into a set representation, allowing to approximate distance measures over input sequences using distance measures over sets. The sets are then represented by an efficient data structure - the Bloom filter -, which allows evaluation of certain set operations without storing the actual elements of the possibly large set. This representation yields low distortion for comparing similar sequences. Operations upon the set representation are carried out using efficient, partially homomorphic cryptographic systems for data confidentiality of the inputs. The output can be adjusted to either return the actual approximated distance or the result of an in-range check of the approximated distance. b) Building upon this efficient basic protocol we introduce the first mechanism to reduce the success of inference attacks by detecting and rejecting similar queries in a privacy-preserving way. This is achieved by generating generalized commitments for inputs. This generalization is done by treating inputs as messages received from a noise channel, upon which error-correction from coding theory is applied. This way similar inputs are defined as inputs having a hamming distance of their generalized inputs below a certain predefined threshold. We present a protocol to perform a zero-knowledge proof to assess if the generalized input is indeed a generalization of the actual input. Furthermore, we generalize a very efficient inference attack on privacy-preserving sequence comparison protocols and use it to evaluate our inference-control mechanism. c) The third part of the framework lightens the computational load of the client taking part in the comparison protocol by presenting a compression mechanism for partially homomorphic cryptographic schemes. It reduces the transmission and storage overhead induced by the semantically secure homomorphic encryption schemes, as well as encryption latency. The compression is achieved by constructing an asymmetric stream cipher such that the generated ciphertext can be converted into a ciphertext of an associated homomorphic encryption scheme without revealing any information about the plaintext. This is the first compression scheme available for partially homomorphic encryption schemes. Compression of ciphertexts of fully homomorphic encryption schemes are several orders of magnitude slower at the conversion from the transmission ciphertext to the homomorphically encrypted ciphertext. Indeed our compression scheme achieves optimal conversion performance. It further allows to generate keystreams offline and thus supports offloading to trusted devices. This way transmission-, storage- and power-efficiency is improved. We give security proofs for all relevant parts of the proposed protocols and algorithms to evaluate their security. A performance evaluation of the core components demonstrates the practicability of our proposed solutions including a theoretical analysis and practical experiments to show the accuracy as well as efficiency of approximations and probabilistic algorithms. Several variations and configurations to detect similar inputs are studied during an in-depth discussion of the inference-control mechanism. A human mitochondrial genome database is used for the practical evaluation to compare genomic sequences and detect similar inputs as described by the use-case. In summary we show that it is indeed possible to construct an efficient and privacy-preserving (genomic) sequences comparison, while being able to control the amount of information that leaves the comparison. To the best of our knowledge we also contribute to the field by proposing the first efficient privacy-preserving inference detection and control mechanism, as well as the first ciphertext compression system for partially homomorphic cryptographic systems.

We investigate the development of collaborative data dashboards, comprised of web visualization components. For this, we explore the use of Lively Web as a development platform and provide a framework for developing web collaborative scientific visualizations. We use a modern thin-client approach that moves most of the specific application processing logic from the client side to the server side, leveraging the implementation of reusable web services. As a web application, it provides users with multi-platform and multi-device compatibility along with enhanced concurrent access from remote locations. Our platform focuses on providing reusable, interactive, extensible and tightly- integrated web visualization components. Such visualization components are designed to be readily usable in distributed-synchronous collaborative environments. As use case we consider the development of a dashboard for researchers working with bioinformatics datasets, in particular Poxviruses data. We argue that our thin-client approach for developing web collaborative visualizations can greatly benefit researchers in different geographic locations in their mission of analyzing datasets as a team. / Graduate

This diploma thesis deals with the issue of the development of mobile thin client application which is able to manage commercial infrastructure cloud service. The introduction section provides an overview of the necessary terminology and presents the problem domain that is a subject of this thesis. Besides the project itself, of which result is the main output of this work, is also the part dedicated to research of current theses, school information resources, guidelines, recommendations and methodologies that covers topics of design and implementation of graphical user interfaces for mobile devices, especially for those that have the Android operating system installed. Information obtained on basis of the research is after used as a default knowledge base for design and implementation of the presentation layer of the previously mentioned application. The next aim of this thesis is to make analysis of requirements for new application which is being developed. The requirements are then transformed into conceptual design, to which is bound the explanation of implementation of individual application layers. UML was mainly used for the modeling of the application parts design in environment of the Sybase PowerDesigner. The programming process was performed by usage of the development environment called Eclipse SDK. Benefit of this diploma thesis lies in the possibility of reusing its concentrated knowledge resulting from the research dealing with the problems of creating GUI for mobile devices. Programmer, who is untouched in this specialization, will be able to use this part of the thesis as a critical study material which has been verified in practice. Cloud infrastructure solution providers can find there an inspiration for their own mobile thin client application.