As per the definition provided by the National Institute for Standards and Technology (NIST) (Badger et al., 2011), “cloud computing is a model for enabling expedient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be quickly provisioned and released with minimal management effort or service provider interaction”. It represents a paradigm shift in information technology many of us are likely to see in our lifetime. While the customers are excited by the opportunities to reduce the capital costs, and the chance to divest themselves of infrastructure management and focus on core competencies, and above all the agility offered by the on-demand provisioning of computing, there are issues and challenges which need to be addressed before a ubiquitous adoption may happen. Cloud computing refers to both the applications delivered as services over the Internet and the hardware and systems software in the datacenters that provide those services. There are four basic cloud delivery models, as outlined by NIST (Badger et al., 2011), based on who provides the cloud services. The agencies may employ one model or a combination of different models for efficient and optimized delivery of applications and business services.
Challenges, Cloud Computing, Security, Techniques.