Foundations of efficient virtual appliance based service deployments

The use of virtual appliances could provide a flexible solution to services deployment. However, these solutions suffer from several disadvantages: (i) the slow deployment time of services in virtual machines, and (ii) virtual appliances crafted by developers tend to be inefficient for deployment purposes. Researchers target problem (i) by advancing virtualization technologies or by introducing virtual appliance caches on the virtual machine monitor hosts. Others aim at problem (ii) by providing solutions for virtual appliance construction, however these solutions require deep knowledge about the service dependencies and its deployment process. This dissertation aids problem (i) with a virtual appliance distribution technique that first identifies appliance parts and their internal dependencies. Then based on service demand it efficiently distributes the identified parts to virtual appliance repositories. Problem (ii) is targeted with the Automated Virtual appliance creation Service (AVS) that can extract and publish an already deployed service by the developer. This recently acquired virtual appliance is optimized for service deployment time with the proposed virtual appliance optimization facility that utilizes active fault injection to remove the non-functional parts of the appliance. Finally, the investigation of appliance distribution and optimization techniques resulted the definition of the minimal manageable virtual appliance that is capable of updating and configuring its executor virtual machine. The deployment time reduction capabilities of the proposed techniques were measured with several services provided in virtual appliances on three cloud infrastructures. The appliance creation capabilities of the AVS are compared to the already available virtual appliances offered by the various online appliance repositories. The results reveal that the introduced techniques significantly decrease the deployment time of virtual appliance based deployment systems. As a result these techniques alleviated one of the major obstacles before virtual appliance based deployment systems

Restorative practice and behaviour management in schools: discipline meets care.

The history of restorative practices in New Zealand schools is directly related to projects such as the Suspension Reduction Initiative (SRI) and the more recent Student Engagement Initiative (SEI); thus the origins of restorative practices in schools are linked with behaviour management and school discipline. During the same period, teachers' work has become more complex: They are working with an increasingly diverse range of students, which in turn requires epistemologically diverse teaching and relationship-building approaches to ensure maximum participation for all. Teachers are looking for new and better ways to interact with students in their classrooms, and those responsible for disciplinary systems are looking to restorative practice for new ways to resolve the increasing range and number of difficulties between teachers and students, students and other students, and between the school and parents. Restorative practices (RP) are currently seen as a way of achieving all this, so they carry a huge burden of hope. Relationship skills are a key competency in the new curriculum, and the philosophy of restoration offers both a basis for understanding and a process for putting this agenda into practice. In effect, it means educating for citizenship in a diverse world, including teaching the skills of conflict resolution. If we accept this philosophy, the curriculum for teacher education will require significant changes in what students are taught about behaviour and classroom management

A discursive approach to relationship practices in classrooms: An exploratory study

In today’s increasingly diverse classrooms it is well accepted that the relationship practices employed by teachers have consequences for the quality of the learning environment. Well chosen relationship practices are thought not only to help teachers to manage their classes but they can contribute to achieving desired educational outcomes. The principles and processes of restorative practice (RP) are seen by many to offer a significant contribution to relationship practices in schools. One of the challenges of realising this potential is to adapt RP for daily classroom use. However, increasing heterogeneity in the student population makes the classroom a complex environment where teachers and students are likely to operate from a range of paradigms of relationship. This study proposes that a discursive conceptualisation of relational identity supports the development of more equitable relationships. It is argued that this then manifests in greater individual and communal well-being. The research involved the development of specific conversational moves adapted from narrative therapy, which were taught to 39 teachers in two schools through a series of four workshops. Following the workshops, a series of seven focus group meetings were held in which teachers engaged in a process of guided deconstructive reflection. The study set out to investigate the contributions of both the conversational moves and the reflective group practices to teachers’ capacity for relationship management (with both students and adults), teaching, and maintaining their own well-being. The focus groups had a triple function of skill practice, reflection and sharing concerns. The group discussions were audio-taped. Examples given by participants of the effects of using the conversational moves were documented. The teachers’ concern narratives were analysed using Foucauldian Discourse Analysis. The study suggests that the use of both discursive conversation practices and deconstructive reflection increased the participants’ capacity for dialogue and tolerating differences. Deconstructive readings of the teachers’ concern narratives identified teacher-student conflicts as a product of multiple positionings and confusion about their respective roles. Deconstructive analysis exposed a range of discourses of care, professionalism, pedagogy and gender as problematic, often placing teachers and students in opposition, and undermining teaching and learning. These findings suggest that systematic deconstructive reflection can usefully inform teachers’ relational strategies in the classroom. It can provide the opportunity for individual teachers to develop an understanding of themselves as teachers, and at the same time it offers useful appreciation of the discursive influences operating in the wider school culture. Some of these discourses deserve critical attention as they are central to the development of teachers’ professional identities. This thesis argues that a discursive approach to relationship practice can support the development of teachers’ capacity to manage the complexities of their work, and as such it is also restorative practice. This critical theoretical approach offers significant potential for explaining how a collaborative relationship paradigm can be understood, practised, and studied

Virtual appliance size optimization with active fault injection

Virtual appliances store the required information to instantiate a functional Virtual Machine (VM) on Infrastructure as a Service (IaaS) cloud systems. Large appliance size obstructs IaaS systems to deliver dynamic and scalable infrastructures according to their promise. To overcome this issue, this paper offers a novel technique for virtual appliance developers to publish appliances for the dynamic environments of IaaS systems. Our solution achieves faster virtual machine instantiation by reducing the appliance size while maintaining its key functionality. The new virtual appliance optimization algorithm identifies the removable parts of the appliance. Then, it applies active fault injection to remove the identified parts. Afterward, our solution assesses the functionality of the reduced virtual appliance by applying the-appliance developer provided-validation algorithms. We also introduce a technique to parallelize the fault injection and validation phases of the algorithm. Finally, the prototype implementation of the algorithm is discussed to demonstrate the efficiency of the proposed algorithm through the optimization of two well-known virtual appliances. Results show that the algorithm significantly decreased virtual machine instantiation time and increased dynamism in IaaS systems. © 2012 IEEE

Fostering energy-awareness in scientific cloud users

© 2014 IEEE.Academic cloud infrastructures are constructed and maintained so they minimally constrain their users. Since they are free and do not limit usage patterns, academics developed such behavior that jeopardizes fair and flexible resource provisioning. For efficiency, related work either explicitly limits user access to resources, or introduces automatic rationing techniques. Surprisingly, the root cause (i.e., the user behavior) is disregarded by these approaches. This paper compares academic cloud user behavior to its commercial equivalent. We deduce, that academics should behave like commercial cloud users to relieve resource provisioning. To encourage this behavior, we propose an architectural extension to academic infrastructure clouds. We evaluate our extension via a simulation using real life academic resource request traces. We show a potential resource usage reduction while maintaining the unlimited nature of academic clouds

Cloud Workload Prediction by Means of Simulations

Clouds hide the complexity of maintaining a physical infrastructure with a disadvantage: they also hide their internal workings. Should users need to know about these details e.g., to increase the reliability or performance of their applications, they would need to detect slight behavioural changes in the underlying system. Existing solutions for such purposes offer limited capabilities. This paper proposes a technique for predicting background workload by means of simulations that are providing knowledge of the underlying clouds to support activities like cloud orchestration or workflow enactment. We propose these predictions to select more suitable execution environments for scientific workflows. We validate the proposed prediction approach with a biochemical application

An SLA-based resource virtualization approach for on-demand service provision

Cloud computing is a newly emerged research infrastructure that builds on the latest achievements of diverse research areas, such as Grid computing, Service-oriented computing, business processes and virtualization. In this paper we present an architecture for SLA-based resource virtualization that provides an extensive solution for executing user applications in Clouds. This work represents the first attempt to combine SLA-based resource negotiations with virtualized resources in terms of on-demand service provision resulting in a holistic virtualization approach. The architecture description focuses on three topics: agreement negotiation, service brokering and deployment using virtualization. The contribution is also demonstrated with a real-world case study

An interoperable and self-adaptive approach for SLA-based service virtualization in heterogeneous Cloud environments

Cloud computing is a newly emerged computing infrastructure that builds on the latest achievements of diverse research areas, such as Grid computing, Service-oriented computing, business process management and virtualization. An important characteristic of Cloud-based services is the provision of non-functional guarantees in the form of Service Level Agreements (SLAs), such as guarantees on execution time or price. However, due to system malfunctions, changing workload conditions, hard- and software failures, established SLAs can be violated. In order to avoid costly SLA violations, flexible and adaptive SLA attainment strategies are needed. In this paper we present a self-manageable architecture for SLA-based service virtualization that provides a way to ease interoperable service executions in a diverse, heterogeneous, distributed and virtualized world of services. We demonstrate in this paper that the combination of negotiation, brokering and deployment using SLA-aware extensions and autonomic computing principles are required for achieving reliable and efficient service operation in distributed environments. © 2012 Elsevier B.V. All rights reserved

Fostering energy-awareness in simulations behind scientific workflow management systems

© 2014 IEEE.Scientific workflow management systems face a new challenge in the era of cloud computing. The past availability of rich information regarding the state of the used infrastructures is gone. Thus, organising virtual infrastructures so that they not only support the workflow being executed, but also optimise for several service level objectives (e.g., Maximum energy consumption limit, cost, reliability, availability) become dependent on good infrastructure modelling and prediction techniques. While simulators have been successfully used in the past to aid research on such workflow management systems, the currently available cloud related simulation toolkits suffer form several issues (e.g., Scalability, narrow scope) that hinder their applicability. To address this need, this paper introduces techniques for unifying two existing simulation toolkits by first analysing the problems with the current simulators, and then by illustrating the problems faced by workflow systems through the example of the ASKALON environment. Finally, we show how the unification of the selected simulators improve on the the discussed problems

Autonomic SLA-Aware service virtualization for distributed systems

Cloud Computing builds on the latest achievements of diverse research areas, such as Grid Computing, Service-oriented computing, business processes and virtualization. Managing such heterogeneous environments requires sophisticated interoperation of adaptive coordinating components. In this paper we introduce an SLA-aware Service Virtualization architecture that provides non-functional guarantees in the form of Service Level Agreements and consists of a three-layered infrastructure including agreement negotiation, service brokering and on demand deployment. In order to avoid costly SLA violations, flexible and adaptive SLA attainment strategies are used with a failure propagation approach. We demonstrate the advantages of our proposed solution with a biochemical case study in a Cloud simulation environment. © 2011 IEEE