Guaranteed Quality of Service in Cloud Ready Application

Cloud computing is a grid based application which eases "On demand network access to a shared pool of computing recourses". This environment strives to be secure, scalable and customized with guaranteed Quality of Service (QoS). However, QoS is guaranteed through fulfillment of non-functional requirements like Security, Scalability, Mobility and Virtualization in Cloud computing System. In this paper we proposed "the Open Cloud Security Architecture (OCSA) algorithm" is an approach to fulfillment of our goal. To meet the computing demands of everyday operations like Nonfunctional requirements, here we have introduced OCSA to achieve that first security, the misuse case and Attack Tree analysis posed threat and Attack Surface of any Cloud, Second scalability to overcome network traffic congestion and Denial of Service (DoS) because of rapid growth of customers and Third, Storage and Service providing consequences arise and mitigated to achieve Mobility and Virtualization. The above unpredictable constraints can be modeled through DREAD analysis, So that above consequences partly annihilated and use of Cloud can be extended by adding more capacity on demand.