An Epistemic Event-based Correlation Scheme for Pervasive Network Management

Computer networks produce tremendous amounts of event-based data that can be collected and managed to support an increasing number of new classes of pervasive applications. Examples of such applications are network monitoring and crisis management. Although the problem of distributed event-based management has been addressed in the non-pervasive settings such as the Internet, the domain of pervasive networks has its own characteristics that make these results non-applicable. Many of these applications are based on time-series data that possess the form of time-ordered series of events. Such applications also embody the need to handle large volumes of unexpected events, often modified on-the-fly, containing conflicting information, and dealing with rapidly changing contexts while producing results with low-latency. Correlating events across contextual dimensions holds the key to expanding the capabilities and improving the performance of these applications. This dissertation addresses this critical challenge. It establishes an effective scheme for complex-event semantic correlation. The scheme examines epistemic uncertainty in computer networks by fusing event synchronization concepts with belief theory. Because of the distributed nature of the event detection, time-delays are considered. Events are no longer instantaneous, but duration is associated with them. Existing algorithms for synchronizing time are split into two classes, one of which is asserted to provide a faster means for converging time and hence better suited for pervasive network management. Besides the temporal dimension, the scheme considers imprecision and uncertainty when an event is detected. A belief value is therefore associated with the semantics and the detection of composite events. This belief value is generated by a consensus among participating entities in a computer network. The scheme taps into in-network processing capabilities of pervasive computer networks and can withstand missing or conflicting information gathered from multiple participating entities. Thus, this dissertation advances knowledge in the field of network management by facilitating the full utilization of characteristics offered by pervasive, distributed and wireless technologies in contemporary and future computer networks.

Knowledge Exchange Institutional Repository Workshop

The workshop took place on 16-17 January in Utrecht, with Seventy experts from eight European countries in attendance. The workshop was structured in six sessions: usage statistics research paper metadata exchanging information author identification Open Archives Initiative eTheses Following the workshop, the discussion groups were asked to continue their collaboration and to produce a report for circulation to all participants. The results can be downloaded below. The recommendations contained in the reports above have been reviewed by the Knowledge Exchange partner organisations and formed the basis for new proposals and the next steps in Knowledge Exchange work with institutional repositories. Institutional Repository Workshop - Next steps During April and May 2007 Knowledge Exchange had expert reviewers from the partner organisations go though the workshop strand reports and make their recommendations about the best way to move forward, to set priorities, and find possibilities for furthering the institutional repository cause. The KE partner representatives reviewed the reviews and consulted with their partner organisation management to get an indication of support and funding for the latest ideas and proposals, as follows: Pragmatic interoperability During a review meeting at JISC offices in London on 31 May, the expert reviewers and the KE partner representatives agreed that ‘pragmatic interoperability' is the primary area of interest. It was also agreed that the most relevant and beneficial choice for a Knowledge Exchange approach would be to aim for CRIS-OAR interoperability as a step towards integrated services. Within this context, interlinked joint projects could be undertaken by the partner organisations regarding the areas that most interested them. Interlinked projects The proposed Knowledge Exchange activities involve interlinked joint projects on metadata, persistent author identifiers, and eTheses which are intended to connect to and build on projects such as ISPI, Jisc NAMES and the Digital Author Identifier (DAI) developed by SURF. It is important to stress that the projects are not intended to overlap, but rather to supplement the DRIVER 2 (EU project) approaches. Focus on CRIS and OAR It is believed that the focus on practical interoperability between Current Research Information Systems and Open Access Repository systems will be of genuine benefit to research scientists, research administrators and librarian communities in the Knowledge Exchange countries; accommodating the specific needs of each group. Timing June 2007: Write the draft proposal by KE Working Group members July 2007: Final proposal to be sent to partner organisations by KE Group August 2007: Decision by Knowledge Exchange partner organisations.

FRAMEWORK SYNTHESIS FOR SYMBOLIC EXECUTION OF EVENT-DRIVEN FRAMEWORKS

Symbolic execution is a powerful program analysis technique, but it is very challenging to apply to programs built using event-driven frameworks, such as Android. The main reason is that the framework code itself is too complex to symbolically execute. The standard solution is to manually create a framework model that is simpler and more amenable to symbolic execution. However, developing and maintaining such a model by hand is difficult and error-prone. We claim that we can leverage program synthesis to introduce a high-degree of automation to the process of framework modeling. To support this thesis, we present three pieces of work. First, we introduced SymDroid, a symbolic executor for Android. While Android apps are written in Java, they are compiled to Dalvik bytecode format. Instead of analyzing an app’s Java source, which may not be available, or decompiling from Dalvik back to Java, which requires significant engineering effort and introduces yet another source of potential bugs in an analysis, SymDroid works directly on Dalvik bytecode. Second, we introduced Pasket, a new system that takes a first step toward automatically generating Java framework models to support symbolic execution. Pasket takes as input the framework API and tutorial programs that exercise the framework. From these artifacts and Pasket's internal knowledge of design patterns, Pasket synthesizes an executable framework model by instantiating design patterns, such that the behavior of a synthesized model on the tutorial programs matches that of the original framework. Lastly, in order to scale program synthesis to framework models, we devised adaptive concretization, a novel program synthesis algorithm that combines the best of the two major synthesis strategies: symbolic search, i.e., using SAT or SMT solvers, and explicit search, e.g., stochastic enumeration of possible solutions. Adaptive concretization parallelizes multiple sub-synthesis problems by partially concretizing highly influential unknowns in the original synthesis problem. Thanks to adaptive concretization, Pasket can generate a large-scale model, e.g., thousands lines of code. In addition, we have used an Android model synthesized by Pasket and found that the model is sufficient to allow SymDroid to execute a range of apps.

Public firm sponsorship of open source software: A knowledge-based approach to open innovation

As an emerging innovation paradigm gaining momentum in recent years, the open innovation paradigm is calling for greater theoretical depth and more empirical research. This dissertation proposes that open innovation in the context of open source software sponsorship may be viewed as knowledge strategies of the firm. Hence, this dissertation examines the performance determinants of open innovation through the lens of knowledge-based perspectives. Using event study and regression methodologies, this dissertation found that these open source software sponsorship events can indeed boost the stock market performance of US public firms. In addition, both the knowledge capabilities of the firms and the knowledge profiles of the open source projects they sponsor matter for performance. In terms of firm knowledge capabilities, internet service firms perform better than other firms owing to their advantageous complementary capabilities. Also, strong knowledge exploitation capabilities of the firm are positively associated with performance. In terms of the knowledge profile of sponsored projects, platform projects perform better than component projects. Also, community-originated projects outperform firm-originated projects. Finally, based on these findings, this dissertation discussed the important theoretical implications for the strategic tradeoff between knowledge protection and sharing.