Information Technology Reference
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support for this evolutionary relationship among Grids and Clouds. The evolu-
tion from Grids to Clouds resulted from the concrete requirements of the players
involved in a Grid ecosystem, in particular in the case of HPC application of Grid
computing.
As the Business Experiments presented in chapters 9 and 10 illustrated, the
establishment of HPC offerings on the market requires a functioning ecosystem
consisting of utility computing providers, SaaS provides and users. In particular, the
first two players are strongly interrelated and interdependent. The utility computing
providers emerge mainly from technology providers as for example Sun, IBM, HP
and others. New entrants to the market as Amazon with its EC2 offerings are for the
moment rather an exception. A common characteristic of these providers is strong
technical knowledge and availability of major data and server farms. While these
providers have a strong knowledge in providing infrastructure with high quality,
they lack at the same time applications that can run on the available infrastructure.
Thus, availability of utility computing offerings alone is not sufficient. There also
need to be Grid-enabled applications that can run on them. Such Grid-enabled appli-
cations are provided by independent software vendors (ISV) that are switching to
the SaaS paradigm. However, while they are building knowledge how to best turn
applications into SaaS, they are lacking the knowledge and resources to build up
Grid infrastructure on which SaaS applications can run. Thus, utility computing
and SaaS providers have complementary needs and requirements. Utility computing
providers need to provide their offerings in a manner that makes it easy for SaaS
to develop their applications on top of the available infrastructure. The example of
Sun, one of the first movers in the utility computing market, shows that only utility
computing offerings might not be sufficient. A clear interface for SaaS providers
and developers is required (see also Fellows 2009). Utility computing providers
have to move in the direction of SaaS and provide open environments on which SaaS
applications can be developed and run. The findings from the Business Experiments
in the BEinGRID project showed a similar tendency. To support faster growth of
SaaS offerings and their adoption, access to utility computing is required (see also
Stanoevska-Slabeva at al. 2008a).
The three levels of Cloud computing - Iaas, PaaS and SaaS - offer the vertical
integration needed to support the complementary needs of utility and SaaS providers
(see fig. 13.1).
The infrastructure on the lowest level is represented through defined interfaces
and in a virtualized manner in form of a platform for SaaS developers. The PaaS level
provides the necessary development environment for SaaS developers to develop
and test SaaS applications and to source infrastructure from the IaaS layer in a flex-
ible and scalable manner. Finally, the SaaS layer presents the combined offering
to the end user. The end users, the third players in the ecosystem, are interested in
flexible applications. This means, the more modular and combinable the services
are the more interesting for end user companies. Thus, provisioning of the services
in small, interconnectable pieces, for example mash-ups (see also Foster et al. 2008,
Hoyer and Stanoevska-Slabeva 2009), would provide the necessary flexibility for
the end user and allow for horizontal integration within and among different SaaS
