A Middleware Layer for Flexible and Cost-Efficient Multi-tenant Applications

摘要

Application-level multi-tenancy is an architectural design principle for Software-as-a-Service applications to enable the hosting of multiple customers (or tenants) by a single application instance. Despite the operational cost and maintenance benefits of application-level multi-tenancy, the current middleware component models for multi-tenant ap-plication design are inflexible with respect to providing different software variations to different customers. In this paper we show that this limitation can be solved by a multi-tenancy support layer that combines dependency injection with middle-ware support for tenant data isolation. Dependency injection enables injecting different software variations on a per tenant basis, while dedi-cated middleware support facilitates the separation of data and config-uration metadata between tenants. We implemented a prototype on top of Google App Engine and we evaluated by means of a case study that the improved flexibility of our approach has little impact on operational costs and upfront application engineering costs.