3、situationoffersasoilforgrowingofCloudcomputer.Second,Softwareengineeringchangedthewayoffaceingtheservicesuchasfacingmachine,languageandmiddlewareintothewayoffacingserviceandneed.ThatmadeSAAS(Software as a Service)tocometrue.Third,theusersbeginningtopaycloseattentiontocorebusinessmoreandmore.Th
4、eydon'tneedtobecomeareal“Amateurengineers”.ItiswhattheCloudcomputerbroughttheimportantchangingonthewayofusingITfacilityforusers.Cloud computing is a resource delivery and usage model, it means get resource (Hardware, software)via network. The network of providing resource is called ‘Cloud’. Th
5、e hardware resource in the ‘Cloud’ seems scalable infinitely and can be used whenever.1.2Theprincipleofcloudcomputing1.2.1threemethodofcalculation:ParallelprocessingParallelprocessingcomputersystemcanperformacalculationoftwoormoreprocessors.Processorscanworksimultaneouslyondifferentaspectsofth