Abstract: PaaS (Platform-as-a-Service) is one of the key services in cloud computing,which provides high availability and scalable development and runtime environment for applications.However,when the applications running on a PaaS platform need to be updated,current PaaS platforms lose their high availability due to the lack of effective support for dynamic updating.To solve the problem,based on current research on software dynamic updating technology,we introduced a PaaS oriented dynamic software updating framework.With extensions of transaction management,dynamic dependence management and version management,we realized instance-level dynamic update for applications on PaaS platforms.We implemented the technical framework on Cloud Foundry to demonstrate the effectiveness of our technology.

Key words: PaaS,Dynamic updating,Cloud Foundry