ROAD4SaaS: Scalable Business Service-Based SaaS Applications

Software-as-a-Service (SaaS) is a software delivery model gaining popularity. Service Oriented Architecture (SOA) is widely used to construct SaaS applications due to the complementary characteristics in the two paradigms. Scalability has always been one of the major requirements in designing SaaS applications to meet the fluctuating demand. However, constructing SaaS applications using third-party business services raises additional challenges for the scalability of the application due to the partner services’ variability and autonomy. Any approach used to develop scalable service-based SaaS applications that compose business services needs to consider these characteristics. In this paper we present an approach to deploy scalable business service compositions based on the concept of an extensible hierarchy of virtual organisations. The explicit representation of relationships in the organisation allows capturing commonalities and variations of relationships between business services while its extensibility allows scale-out/in the SaaS application instance.