Faculty Publications

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Author: search.filters.author.Achar, R.

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    Web service selection based on Requester's Offering constraints
    (2008) D’Mello, D.A.; Ananthanarayana, V.S.; Achar, R.
    Web service selection is a mechanism to select the most suitable Web service that satisfies requester's various nonfunctional requirements. In e-business environment, the business offers play a major role in attracting a numerous consumers. In order to find the most profitable service offering a valuable business offer, there is a need for the selection mechanism to rank the functionally similar Web services based on the provider's business offers and the requester's requirements on various business offers. In this paper, we propose an XML model to represent requester's complex requirements on multiple business offers. The paper explores the Web service selection mechanism which selects and ranks the functionally similar Web services based on the requester's requirements on business offers. The paper also presents the broker based architecture for business offer aware Web services publishing and selection. Finally, we present a scheme to represent the requester's alternative requirements on business offers and extend the selection mechanism to handle a set of alternative business offering requirements.© 2008 IEEE.
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    Business offer driven dynamic web service selection
    (2008) D’Mello, D.A.; Ananthanarayana, V.S.; Achar, R.
    In today's business environment, the business offers have an inevitable importance in giving the buyer the most profitable deal. In order to improve the business, the service providers attract the customers by advertising a lot of attractive offers. There is a need for the selection mechanism which accepts the requester's various requirements on business offers to find the most profitable service. In this paper, we identify various business offers of service providers in e-business domain and broadly classify them based on requester's point of view as, unconditional business offers, conditional business offers and probabilistic business offers. We also provide a vocabulary for various business offers of service providers. The paper explores different types of requester's requirements on business offers and proposes a language to express such requirements on various business offers. We propose a tree structure to represent requester's complex business offer requirements for the business offer driven Web service selection.
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    Optimal scheduling of computational task in cloud using Virtual Machine Tree
    (2012) Achar, R.; Santhi Thilagam, P.; Shwetha, D.; Pooja, H.; Roshn; I Andrea
    The increasing demand in computing resources and widespread adaptation of Service Oriented Architecture (SOA) has made cloud as a new IT delivery mechanism. In cloud, computing resources are provided to the requester as a service, which include Software as a Service (SaaS), Platform as a Service (PaaS) and Infrastructure as a Service (IaaS). Cloud Computing is still in developing stage and faces many challenges. Out of the various issues, scheduling plays a very important role in determining the efficient execution of tasks in cloud environment. In this paper we present a scheduling algorithm which uses tree based data structure called Virtual Machine Tree (VMT) for efficient execution of tasks. The proposed algorithm is tested using CloudSim simulator and the results shows that algorithm gives better performance compared to other traditional scheduling algorithms. © 2012 IEEE.
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    Load balancing in cloud based on live migration of virtual machines
    (2013) Achar, R.; Santhi Thilagam, P.S.; Soans, N.; Vikyath, P.V.; Rao, S.; Vijeth, A.M.
    Cloud computing is an upcoming trend in the field of computer science in recent years. In cloud, computing resources are provided as service in the form of virtual machine to its clients across the globe based on demand. Huge demand for cloud resources results in overutilization of servers whenever there is a heavy load. It is necessary to distribute the load across the servers in cloud by taking into consideration of allocating the right amount of resources dynamically based on the load to improve the performance of applications running in virtual machines. In this paper we present an algorithm which dynamically allocate resources based on the need and distribute the load across the servers. We conducted the experiment on Xen Cloud Platform. We use response time as a metric. The experiments conducted shows that the proposed algorithm improves the performance of applications running in virtual machines by using the feature scaling and migration. © 2013 IEEE.
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    A broker based approach for cloud provider selection
    (Institute of Electrical and Electronics Engineers Inc., 2014) Achar, R.; Santhi Thilagam, P.
    Rapid growth of internet technology made many IaaS providers arise across the globe to meet the needs of small IT companies. Number of IT companies started using resources of IaaS provider due to elastic and pay as you go nature. Increasing number of cloud providers results in difficulty for requester to select suitable cloud provider based on requirements. In this paper we present a broker based architecture for selecting suitable cloud provider from multiple providers. The broker measure the quality of each cloud provider and prioritize them based on the needs of the requester. The experiment is conducted using cloudsim simulator shows that proposed architecture selects suitable cloud provider. © 2014 IEEE.
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    Dynamic resource allocation for multi-tier applications in cloud
    (Springer Verlag service@springer.de, 2016) Achar, R.; Santhi Thilagam, P.; Meghana; Niha Fathima Haris, B.; Bhat, H.; Ekta, K.
    Increasing demand for computing resources and widespread adaption of service-oriented architecture has made cloud as a new IT delivery mechanism. Number of cloud providers offer computing resources in the form of virtual machines to the cloud customers based on business requirements. Load experienced by the present business applications hosted in cloud are dynamic in nature. This creates a need for a mechanism which allocates resources dynamically to the applications in order to minimize performance degradations. This paper presents a mechanism which dynamically allocates the resources based on load of the application using vertical and horizontal scaling. Cloud environment is set up using Xen cloud platform and multi-tier web application is deployed on virtual machines. Experimental study conducted for various loads show that proposed mechanism ensures the response time is within the acceptable range. © Springer Science+Business Media Singapore 2016.
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    Broker-based mechanism for cloud provider selection
    (Inderscience Publishers, 2020) Achar, R.; Santhi Thilagam, P.; Acharya, S.
    Cloud computing has recently emerged as a new computing paradigm for delivering on demand virtualised computing resources over the internet on a pay-as-use basis. Applications hosted in cloud have different requirements which include both low level (resource) requirements and high level (performance) requirements. However, most of the cloud providers satisfy SLAs based on resource requirements rather than providing performance guarantees to applications. This gap creates a need for selecting a more suitable cloud provider who can satisfy performance requirements of applications along with resource requirements. This work aims at proposing a broker-based approach to rank cloud providers based on QoS requirements of customers. It helps the SaaS providers to save cost and complexity in choosing a suitable cloud provider for hosting applications. The experimental results show that proposed approach selects the suitable cloud provider for hosting various types of applications satisfying the needs of different cloud customers. © 2020 Inderscience Enterprises Ltd.
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    Live migration of virtual machines with their local persistent storage in a data intensive cloud
    (Inderscience Enterprises Ltd. editor@inderscience.com, 2017) Modi, A.; Achar, R.; Santhi Thilagam, P.S.
    Processing large volumes of data to drive their core business has been the primary objective of many firms and scientific applications in these days. Cloud computing being a large-scale distributed computing paradigm can be used to cater for the needs of data intensive applications. There are various approaches for managing the workload on a data intensive cloud. Live migration of a virtual machine is the most prominent paradigm. Existing approaches to live migration use network attached storage where just the run time state needs to be transferred. Live migration of virtual machines with local persistent storage has been shown to have performance advantages like security, availability and privacy. This paper presents an optimised approach for migration of a virtual machine along with its local storage by considering the locality of storage access. Count map combined with a restricted block transfer mechanism is used to minimise the downtime and overhead. The solution proposed is tested by various parameters like bandwidth, write access patterns and threshold. Results show the improvement in downtime and reduction in overhead. © © 2017 Inderscience Enterprises Ltd.
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    Applications nature aware virtual machine provisioning in cloud
    (Inderscience Publishers, 2018) Achar, R.; Santhi Thilagam, P.S.
    Rapid growth of internet technologies and virtualisation has made cloud as a new IT delivery mechanism, which is gaining popularity from both industry and academia. Huge demand for a cloud resources, running similar nature applications in the same server results in application degradation whenever there is a sudden rise in workload. In order to minimise the application degradations, there is an urgent need to know the nature of applications running in cloud for efficient virtual machine (VM) provisioning. Existing cloud architecture does not provide any mechanism to handle this issue. This paper presents a modified cloud architecture which contains additional component called application analyser to identify the nature of applications running in each VM. Based on applications nature, this paper presents a novel VM provisioning mechanism using genetic algorithm. In order to utilise the resources efficiently, this paper also presents a mechanism for VM provisioning with migration. Experimental study is conducted using CloudSim simulator shows that proposed mechanism is efficiently allocating resources to the virtual machines. © 2018 Inderscience Enterprises Ltd.