David A. Bacigalupo

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Before an application modelled as a directed acyclic graph (DAG) is executed on a heterogeneous system, a DAG mapping policy is often enacted. After mapping, the tasks (in the DAG-based application) to be executed at each computational resource are determined. The tasks are then sent to the corresponding resources, where they are orchestrated in the(More)
This paper reviews current cloud computing business models and presents proposals on how organisations can achieve sustainability by adopting appropriate models. We classify cloud computing business models into eight types: (1) Service Provider and Service Orientation; (2) Support and Services Contracts; (3) In- House Private Clouds; (4) All-In-One(More)
Summary form only given. Predictive performance models of e-Commerce applications allows grid workload managers to provide e-Commerce clients with qualities of service (QoS) whilst making efficient use of resources. We demonstrate the use of two 'coarse-grained' modelling approaches (based on layered queuing modelling and historical performance data(More)
The automatic allocation of enterprise workload to resources can be enhanced by being able to make ‘what-if’ response time predictions, whilst different allocations are being considered. It is important to quantitatively compare the effectiveness of different prediction techniques for use in cloud infrastructures. To help make the comparison(More)
Response time predictions for workload on new server architectures can enhance Service Level Agreement–based resource management. This paper evaluates two performance prediction methods using a distributed enterprise application benchmark. The historical method makes predictions by extrapolating from previously gathered performance data, while the layered(More)
Web service technology will provide a platform for dynamic e-business applications. This paper describes a framework for identifying, monitoring and reporting performance data of critical transactions within a web service using the Java ARM standard, a Transaction Definition Language (TDL) and a bytecode instrumentation tool. The data extracted using this(More)
The automatic allocation of enterprise workload to resources can be enhanced by being able to make what-if response time predictions whilst different allocations are being considered. We experimentally investigate an historical and a layered queuing performance model and show how they can provide a good level of support for a dynamic − urgent cloud(More)
Distributed e-business application platforms such as the web services framework will require sophisticated workload management infrastructures for the routing of client requests to the most appropriate services. This paper introduces a novel and dynamic predictive framework that uses both analytical performance modelling and historical data to extrapolate a(More)
In a multicluster architecture, where jobs can be submitted through each constituent cluster, the job arrival rates in individual clusters may be uneven and the load therefore needs to be balanced among clusters. In this paper we investigate load balancing for two types of jobs, namely non-QoS and QoSdemanding jobs and as a result, two performance-specific(More)
Formative eAssessment can be very helpful in providing high quality higher education assignments. However, there are obstacles restricting the uptake of formative eAssessment in higher education including both cultural and technical issues. When a university is encouraging the uptake of formative eAssessment internally it is useful to have case studies from(More)