Abstract: Cloud computing PaaS (platform as a service) platform draws wide attentions in recent years. Not only does it provide environment and resources for users, it also improves the utilization of hardware resources and reduces business operation costs. However, there is lack of mechanism to constrain the behavior of providers. In order to fill the gap, the concept of topology management was brought up. In one hand, the application topology can monitor the relationship between applications and resources, in another hand, resource topology can monitor the relationship between resources and applications, both of them can realize monitoring of applications from different angles. We use a hash array to store topology information, and the message bus publish-subscribe model to pass the messages. After that, we can achieve the topology information, and then demonstrate the results in Web pages. To sum up, the PaaS platform driven by Cloud Foundry designed and implemented in this paper runs well. It presents the resource pool information and the relationship between application and resources clearly. Thus, the system can improve the quality of services and protect the interests of users. Application topology display and resource topology display can duly reflect the relationship between resources and application of the system, both of them display from different angles can provides great convenience to the cloud provider to manage application.

Key words: cloud computing, application topology, resource topology, PaaS