Feature-based application development and management of multi-tenant applications in clouds

In recent years, there has been a rising interest in cloud computing, which is often used to offer Software as a Service (SaaS) over the Internet. SaaS applications can be offered to clients at a lower cost as they are usually multi-tenant: many end users make use of a single application instance, even when they are from different organisations. It is difficult to offer highly customizable SaaS applications that are still multi-tenant, which is why these SaaS applications are often offered in a one size fits all approach. In some application domains applications must be highly customizable, making it more difficult to migrate them to a cloud environment, and losing the benefits of multi-tenancy. In this paper we compare multiple approaches for the development and management of highly customizable multitenant SaaS applications, and present a methodology for developing and managing these applications. We compare two approaches, an application-based approach focusing on deploying multiple multi-tenant applications variants, and a feature-based approach where applications are composed out of multi-tenant services using a service oriented architecture. In addition, we also discuss a hybrid approach combining properties of both. We conclude that the feature-based approach results in the fewest application instances at runtime resulting in more multi-tenancy.