Browsing by Author "Gallege, Lahiru S."

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    Parallel Methods for Evidence and Trust based Selection and Recommendation of Software Apps from Online Marketplaces
    (ACM, 2017-04) Gallege, Lahiru S.; Raje, Rajeev R.; Computer and Information Science, School of Science
    With the popularity of various online software marketplaces, third-party vendors are creating many instances of software applications ('apps') for mobile and desktop devices targeting the same set of requirements. This abundance makes the task of selecting and recommending (S&R) apps, with a high degree of assurance, for a specific scenario a significant challenge. The S&R process is a precursor for composing any trusted system made out of such individually selected apps. In addition to feature-based information, about these apps, these marketplaces contain large volumes of user reviews. These reviews contain unstructured user sentiments about app features and the onus of using these reviews in the S&R process is put on the user. This approach is ad-hoc, laborious and typically leads to a superficial incorporation of the reviews in the S&R process by the users. However, due to the large volumes of such reviews and associated computing, these two techniques are not able to provide expected results in real-time or near real-time. Therefore, in this paper, we present two parallel versions (i.e., batch processing and stream processing) of these algorithms and empirically validate their performance using publically available datasets from the Amazon and Android marketplaces. The results of our study show that these parallel versions achieve near real-time performance, when measured as the end-to-end response time, while selecting and recommending apps for specific queries.
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    TRUSTED SERVICE COMPOSITION FOR DISTRIBUTED REAL-TIME AND EMBEDDED SYSTEMS
    (Office of the Vice Chancellor for Research, 2012-04-13) Gamage, Dimuthu U.; Gallege, Lahiru S.; Hill, James H.; Raje, Rajeev R.
    Distributed real-time and embedded (DRE) software systems are expected to provide high quality-of-service (QoS) attributes, e.g., scalability, reliability, and security, in conjunction with correct functionality built atop of infrastructure with limited capabilities. Given the many complex and conflicting QoS and functional attributes of DRE systems, a major challenge in developing such software systems is to guaranteeing it trustworthiness, i.e., the degree of confidence that the system adheres to its specification. Current state-of-the-art methods use service orientation to compose systems from reusable and trusted services, and validate the trustworthiness of the end system using runtime evidences. The major shortcoming of this approach is that trust is considered an afterthought (i.e., not an integral part of the software development lifecycle). Trustworthiness of a system should be evaluated based on the trustworthiness of different properties of the system, including its functionality and QoS attributes. Our research extends current state-of-the-art methods for developing trusted DRE systems by considering development time factors of the composition (e.g., properties of individual services, interaction patterns, and compatibility with other services). It is a major research challenge to evaluate the composition of trustworthiness for different system properties with different composition patterns. Our current and future research work to address this challenge includes identifying trust composition operators for different types of compositions, deriving a formal model of trust composition, and validating our approach with a case study using a distributed tracking system.
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    TRUSTED SERVICE REPRESENTATION AND SELECTION FOR GENERATING DISTRIBUTED REAL-TIME AND EMBEDDED SYSTEMS
    (Office of the Vice Chancellor for Research, 2012-04-13) Gallege, Lahiru S.; Gamage, Dimuthu U.; Hill, James H.; Raje, Rajeev R.
    Today’s enterprise distributed real-time and embedded (DRE) systems are created from reusable software components and services. This approach is promising because of its economic advantages (e.g., maximizing reuse of existing business-logic). It, however, is plagued by the challenge of selecting a subset of software components and services from those that are readily available because the selection process can be both costly and time-consuming, and the description of available services is often ambiguous and easy to misinterpret. Moreover, there is always the chance that a selected service does not adhere to its promises. This implies that trust, which we de-fine as the degree of confidence that a software component or service ad-heres to its specification, plays an important role in this selection process. We call this process trusted selection. Current state-of-the-art methods use multi-level contracts made up of four levels (i.e., syntax, semantics, synchronization and Quality of Service (QoS)) to facilitate service and component selection. This method, however, does not take trust into account thereby making it hard to support trusted selection. Our research therefore improves upon state-of-the-art in multi-level specification by incorporating trust contract into it. We incorporate trust into the multi-level specification by representing trust using subjective logic, which evaluates trust using a tuple of belief, disbelief, and uncertainty. Our current results show our trust-enabled multi-level specification reduces mis-interpretation, mismatch, and misuse of selected services.