The SaaS model (Software as a Service) is widely
described in the literature, especially as a very promising emerging economic model [1]. Technological aspects however are a barely discussed, probably because
the SaaS model is not a technology in itself, but relies on various standards and proprietary technologies. Although the SaaS concept is easily understandable, it describes hosted applications that are accessible via the Internet and the Web, there is not a single definition of
the SaaS model. In the broadest sense, the concept includes client-server
applications of the ASP model, with an additional html layer (renaming these applications "SaaS" has allowed among others to get
rid of the ASP label too much related to the Internet bubble and the collapse of
start-ups positioned in this area), and applications written specifically for the Web as well. A distingo still in force, however, is that the term
"SaaS" applies to business (or professional) applications, while consumer
applications are called "Web 2.0". However, given the increasing penetration of Web 2.0 tools and applications in companies and business applications, this distinction
could become obsolete. The pricing model is not unique either: theoritically "on-demand", but also by annual subscription, thus close to the
license acquisition and support pricing model. As with all models in the state of flux, the contours of SaaS are vague and the standards still being developed (see eg. Cloud Computing Interoperability Forum
(CCIF)) but the wealth of the technologies and solutions proposed makes its strength and so the SaaS model will meet the extremely varied needs of user enterprises.
I intend to discuss some
technological aspects of the SaaS in this blog and analyze the implementations based on technologies developed by Sun
Microsystems, such as Containers, xVM, or ZFS. Good readings to start are the cloud relationship model and the understanding cloud computing-saas-paas blog entries for their view of the cloud and some definitions.
[1] Thimothy Chou, "Seven Software Business Models", Active Book Press, 2008
