“…These challenges include security (Feng and Li, 2014), the costing model (i.e., the cost for communications), the charging model (this is from the service provider's perspective and pertains to how the service provider charges for access to the elastic resource pool) and the service level agreement (quality, availability, reliability, and performance of the resources) (Dillo et al, 2010). Cloud systems are also susceptible to the traditional security problems of stand-alone systems such as security vulnerabilities, virus and hack attack (Liu, 2012). The core IT services of several companies are being moved to the cloud.…”