Beschrijving

Software as a service. The words are on everyone's lips. The pages of software industry publications are full of articles about software as a service (SaaS)—articles that use words like "revolution" and "horizon" (as in, "on the…"). Everyone knows (or thinks they know) what it is, roughly, and everyone knows it's going to be big. Yet few people would say they can really define it, and even fewer know how to build it. So, if SaaS holds such promise for the future of application delivery, why isn't there more guidance available to help people actually achieve it? We believe that SaaS is going to have a major impact on the software industry, because software as a service will change the way people build, sell, buy, and use software. For this to happen, though, software vendors need resources and information about developing SaaS applications effectively. This is the first in a series of papers from Microsoft dedicated to demystifying SaaS and providing practical, real-world guidance for architecting SaaS applications. This paper serves as an overview of SaaS, its challenges, and its benefits for those who are interested in offering SaaS. Future papers will explore many of these topics in detail. This paper begins by asking just what software as a service is, exactly, and it explains the conceptual shifts that prospective SaaS vendors must experience in order to understand how it differs from traditional, on-premise software. Next, we'll look at the SaaS business model, to see how software as a service can be monetized in the real world. Because this is an architectural paper, the largest section addresses the architecture of a SaaS application. We present a four-level maturity model that explains and puts into perspective some key attributes of SaaS: configurability, multi-tenant efficiency, and scalability. We'll examine the components of a high level SaaS architecture, and then take a closer look at a typical challenge the SaaS architect faces—that of providing a mechanism for extending the data model of a multi-tenant application. Lastly, we'll take a brief look at some of the operational issues involved in supporting a SaaS application after deployment.