Mixed-Tenancy in the Wild - Applicability of Mixed-Tenancy for Real-World Enterprise SaaS-Applications

Software-as-a-Service (SaaS) is a delivery model whose basic idea is to provide applications to the customer on demand over the Internet. SaaS thereby promotes multi-tenancy as a tool to exploit economies of scale. This means that a single application instance serves multiple customers. However, a major drawback of SaaS is the customers' hesitation of sharing infrastructure, application code, or data with other tenants. This is due to the fact that one of the major threats of multi-tenancy is information disclosure due to a system malfunction, system error, or aggressive actions. So far the only approach in research to counteract on this hesitation has been to enhance the isolation between tenants using the same instance. Our approach (presented in earlier work) tackles this hesitation differently. It allows customers to choose if or even with whom they want to share the application. The approach enables the customer to define their constraints for individual application components and the underlying infrastructure. The contribution of this paper is an analysis of real-world applicability of the mixed-tenancy approach. This is done experimentally by applying the mixed-tenancy approach to OpenERP, an open source enterprise resource planning system used in industry. The conclusion gained from this experiment is that the mixed-tenancy approach is technically realizable for cases of the real world. However, there are scenarios where the mixed-tenancy approach is not economically worthwhile for the operator.