中文摘要：

云环境是一个极具发展前景的网络环境。随着云技术的发展及相关标准的成熟，在可以预见的未来里，云将像当年的互联网一样，从根本上改变我们的生活方式。服务等级协议（SLA）是现有云环境下信息服务双方不可或缺的一项协议。一方面，SLA是云信息服务及服务质量的合法保障；另一方面，SLA也明确规定了服务双方的经济关系，量化了服务赔偿机制。文章从SLA对云服务质量的保障和对提供商、客户双方利益的维护两方面进行了分析，并以此为基础，在云环境下的sLA中引入了服务代理角色，构建了一个简单的SLA模型，探讨了此模型的运作机制。服务双方可以按照协议的模型来实施具体的SLA，以提升服务质量，形成更良好的合作关系。

英文摘要：

Cloud environment, a net environment, has very promising prospects. As the techniques of the cloud environment develop and the relevant standards become mature, it can be predicted that the cloud environment will change the patterns of our lives dramatically just as what internet did in the past two decades. Services level agreement （SLA） is indispensable of the information services in present cloud environment. On one hand, SLA can guarantee the quality of the services of cloud environment; on the other hand, SLA also provides a clear definition to the financial relationship between beth sides in the services so that compensations of these services can he estimated. This article analyzed SLA from two aspects which include how does it ensure the quality of the cloud services and protect the interests of both the providers and clients. Based on the analysis, the article constructed a simple SLA model through introducing service agents into SLA in the cloud environment, and then discussed the working mechanism of this model. Both sides of the services can carry out the specific SLA according to this model in order to promote the service qualities and to form a better cooperation relationship.