云计算已成为众多IT需求的可行模型。在某些情况下,大型企业会按需购买云式CPU周期,使用Amazon、Rackspace和Terremark等供应商提供的“基础设施即服务”(IaaS)进行测试、开发和批处理。其他情况下他们会外包整个应用,如把电子邮件交给Google,CRM交给Salesforce.com,或者把工资单交给ADP。尽管它的确很有价值,但IT专家们仍然热衷于对云计算的价值进行一场哲学辩论。他们想知道为大众设计的云计算和SaaS是否真正是企业数据中心现场 Cloud computing has become a viable model for many IT needs. In some cases, large enterprises buy cloud CPU cycles on demand and test, develop, and batch using “Infrastructure as a Service ” (IaaS) provided by vendors such as Amazon, Rackspace, and Terremark. In other cases they outsource the entire application, such as sending the email to Google, CRM to Salesforce.com, or paying the payroll to ADP. Despite its value, IT experts are still keen on a philosophical debate about the value of cloud computing. They want to know if cloud computing and SaaS designed for the general public are truly enterprise data center sites