“…Neither of these methods take into account the special architectural features and dynamically changing characteristics of cloud computing environments. Examples of such work include [149,14,135,137,131,37,101,4,105,103,68,83,99,61,18,55,82,78,142,30,10,87,12,67,95,150,6,138,74,44,84,122,2,98,71,1,121]. Some of the proposals were developed using a simulation environment or conventional virtualization environment, which obviously miss crucial constraints underlying a real cloud environment [96,76,145,118,135,104,121,64,66,85].…”