As more and more multi-tenant applications emerge in clouds, people increasingly recognize the importance of multi-tenant applications in realizing cloud benefit maximization. Service Level Agreement (SLA) is advocated widely to monitor these applications for multiple tenants to meet their service quality requirements. However, so far these applications provide limited multi-tenant monitoring supports, which prevents the applications from guaranteeing tenants' interests efficiently. In this paper, we propose an aspect-oriented approach to monitor multi-tenant applications based on tenant SLAs. Our approach includes monitoring code generation and runtime management. During code generation, the approach proposes an SLA feature model for tenants to specify variable requirements. Based on the requirements the approach selects code snippets, which are implemented as templates in advance, and splices them into an monitoring aspect. During runtime, the approach prioritizes aspects to determine execution order and updates monitoring status in term of tenant. An implemented prototype is used to evaluate the approach by case studies, which demonstrate the approach effectiveness in common situations.

With the popularity of pads, large touch screens, notebooks and smart mobiles, it is a reasonable requirement that modelers use such devices to models. However, there are few modeling tools that take full advantage of the devices. This paper discusses a Web based UML modeling tool with touch screens, based on our full analysis of human-machine interaction modes for software modeling. The tool provides more input means, i.e. combining gesture input and traditional keyboard and mouse input, and supports cross-platforms modeling by using HTML 5.