Under the traditional model, enterprises to establish a set of IT systems not only need to buy hardware and otherinfrastructure, but also to buy software licenses, the need for specialized staff maintenance. The scale of the enterprisewill continue to upgrade the various hardware and software facilities to meet the needs. For enterprises, computers andother hardware and software itself is not what they really need, they are just to complete the work, to provide effi cienttools only. For individuals, we usually use the computer to install a lot of software, and many software is a fee, theuser is not often used to buy the software is very uneconomical. We only need to pay a small amount of 'rent' to 'rent'to these software services for us to save a lot of money to buy hardware and software. Just as we use electricity everyday, but we are not every self-generator, it is provided by the power plant; we use tap water every day, but we do nothave every well, it is provided by the water plant. This model is great enough to save resources and facilitate our lives.The face of the computer to bring us the troubles, we can like the use of water and ele