24. 美国国家标准技术研究院(NIST)的云计算定义(5-3-4模型) NIST defines cloud computing by describing five essential characteristics, three cloud servicemodels, and four cloud deployment modelssummarized in figure below。 CSA:Security Guidance for Critical Area of Focus in Cloud Computing V2.1 CSA – Cloud Security Alliance(国际云安全联盟)