Date Added: Jul 2011
The current network architectures make difficult reusability and increase costs. These architectures not take into account the changing functional requirements at the application development. Cloud computing is known as an IT environment that includes all elements of the IT and network stack, enabling the development, delivery, and consumption of Cloud Services. In this paper, the authors present a brief introduction to the concept of cloud (types and services). Then they outline a state of the art of different existing solutions of cloud. A comparison tables are also proposed.