Computer Science

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Browsing Computer Science by Author "Iyilade, Johnson Seun"

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    Grid-based utility middleware infrastructure for distributed services provisioning
    (2010) Iyilade, Johnson Seun; Adigun, M.O.
    As Service Oriented Computing becomes the prevalent methodology for engineering distributed applications, service composition remains a key challenge to the reality of on-the-fly application composition using available services in an ecosystem. Current state-of-the-art service composition strategies are based on a predefined sequence of actions or workflow and are unsuitable when applied in dynamic and open settings due to their lack of scalability, fault-tolerance, and high bandwidth cost overhead. To address this problem, this thesis makes the case for a new flexible and adaptive strategy for service composition that is suitable for highly dynamic and open distributed services provisioning environments. To support this thesis and demonstrate our solution approach, we propose MINDS – a Middleware Infrastructure for Distributed Service Provisioning as a platform to analyze and elaborate our service composition strategy. MINDS is based on model of business processes as a collaborative conversation among software agents; It employs late (runtime) binding to services and facilitates richer interactivity of services by enabling services to be active and aware of changes in the user and/or execution environment. We further formulate a new service provisioning life-cycle process for runtime, automated composition based on MINDS strategy. The new life-cycle process is not based on a predefined sequence of actions or workflow but rather on composition goal defined based on user request. To evaluate our strategy and demonstrate its utility and applicability, we implement an experimental prototype for e-Tourism Virtual Enterprise Collaboration as a case study. We also carry out empirical analysis and simulation experiments to compare the performance of MINDS with related strategies using scalability, fault-tolerance and bandwidth cost optimization as performance metrics. The results of the simulation experiments shows that MINDS is scalable as it require lower service matchmaking and composition time when the number of services and tasks increase respectively. Moreover, in a sample of 80 tasks, 34 (representing 42.5%) met deadline when the centralized service agent used in existing strategy failed, while 55 (representing 68.75%) met deadline when decentralized service agents used in MINDS failed. Also, more tasks met deadline in MINDS when the service provider failed than the centralized service agent approach because the failure was discovered at a minimal time. Finally, the simulation results also indicated that MINDS optimize bandwidth by requiring less amount of data traffic on the network. In a sample of 41 participating services in composition, the overhead cost for data transmissions in both decentralized and centralized scheme were respectively, 136 Rands and 267 Rands. We conclude that in view of the limitations of existing strategies for service composition in dynamic and open settings, a new flexible and adaptive middleware strategy as proposed in this thesis becomes imperative. Such a solution offers a more efficient composition strategy in terms of scalability, fault-tolerance and communication cost. It provides the crucial platform required in the actualization of the future “Internet of Services” towards onthe- fly composition and runtime binding of services.