Information Technology Reference
In-Depth Information
3.6.2 Convergence of Grid Computing and Software-as-a-Service
Another important paradigm that is gaining momentum together with Grid
Computing and SOC is the Software-as-a-Service (SaaS) paradigm. The term SaaS
denotes software that is owned, delivered and managed remotely by one or more
independent software providers and that is offered on a pay-per-use basis (see also
Mertz 2007, Wohl 2008). SaaS is consumed over communication networks (typi-
cally the Internet) and can be accessed by the user either via a Web browser or by
directly accessing the application programming interfaces (APIs).
The SaaS concept means substantial changes in the way how software is devel-
oped and consumed. Traditional software or packaged software is developed to run
on the end users' computers. Thus, for running packaged software, the user also has
to provide the required infrastructure, which can result in additional investments.
Further, qualified staff that is capable of providing maintenance and support for the
software and hardware is needed. By buying a software license, a user is granted
the right to use the software. Typical licenses for traditional software are: licences
for usage per time (e.g. one year), licences to use the software for a certain time
and number of computers (e.g. one year and maximum six computers), licences for
a certain period of time and per number of users (e.g. one year and maximum six
people) and similar. In addition, SaaS is provided on a pay-per-use basis. The user
pays for the functionality of the software only for the time and intensity of each
specific usage. The user does not own the software and does not have to bother with
investing in infrastructure for running the software on and in staff required for main-
taining the software. The price-per-use includes a share for the infrastructure and for
licenses (see also Stanoevska-Slabeva et al. 2008).
SaaS is not a new phenomenon. The idea of sharing software, i.e. remote access
to software by several users, has been a vision since the very beginning of distributed
computing in companies. At that time, it was called “time sharing” of software that
runs on a remote server and is used by several users over a private network (Wohl
2008). The next impulse for further evolution of providing applications as a service
came with the establishment of the Internet as the main communication medium.
In 1998, the term “Application Service Provisioning (ASP)” was introduced by
(Heart and Pliskin 2001). ASP evolved from IT outsourcing and is based on the idea
that a web-enabled application can be provided online through IP-based telecom
infrastructure (Xu and Seltsikas 2002) by a central application service provider
(Mittilä and Lehtinen 2005). At the beginning, the ASP model was a typical one-to-
many delivery model, which means that the application is operated in a centralized
manner by the ASP and is offered in the same form to many customers. The main
advantages under which the ASP business model was propagated to customers are:
cost savings and no need for developing and maintaining own infrastructure and
skills. Even though ASP was considered as one very promising business model in
the late 1990s, it did not take up on the market and its adoption has been very slow
(Desai and Currie 2003). One major reason for the failure of ASP was the inability
of early application service providers to offer customized services. The application
was provided in the same form for any customer. There was little possibility for
