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if the previous level has been experienced already. Thus, the introduction of Grid
Computing in companies is a long and evolving process.
First success of Partner/Community Grids inspired further vision in the evolu-
tion of Business Grids: Open Global Grids. Open Global Grids are considered to
be independent platforms, i.e. a global interconnection of multiple, heterogeneous
Grids, composed of infrastructure, middleware and applications as well as based on
a service-oriented infrastructure (see also Next Generation GRIDs Expert Group
(2006). Such a Grid infrastructure can be used by any organization simply by
connecting to it in a plug-and-play manner, i.e. no configuration is required and the
Open Global Grid can be used right upon the connection is established.
3.6 New Trends in Grid Computing
Since broader awareness for Grid Computing in eScience and industry started in
the mid 1990s, Grid Computing concepts have evolved, matured and have been
influenced by other IT phenomena prevailing in the same time. In particular, the
following three developments influenced the current concepts of Grid Computing:
• Service-oriented Computing
• Software-as-as-Service (SaaS)
• Cloud Computing
All three phenomena and their impact on Cloud Computing are described in more
detail below.
3.6.1 Convergence of Grid and Service-oriented Computing
Service-oriented Computing (SOC) is a new computing paradigm that developed
in parallel to Grid Computing. It was motivated and driven by developments and
needs in eBusiness for easy and efficient integration of application within and
across companies (Foster at al. 2002). According to Papazoglou et al. (2006), SOC
is defined as follows:
“Service-oriented Computing (SOC) is a new computing paradigm that utilizes services
as the basic construct to support the development of rapid, low-cost and easy composition
of distributed applications even in heterogeneous environments. The visionary promise
of Service-Oriented Computing is a world of cooperating services where application
components are assembled with a little effort into a network of services that can be loosely
coupled to create flexible dynamic business processes and agile applications that may span
organisations and computing platforms.” (Papazoglou et al. 2006)
Basic building components of SOC are services, which are autonomous, platform-
independent computational entities that can be “…
described, published, discovered,
and loosely coupled in novel ways”
(Papazoglou et al. 2007). Up till now the most
mature and also most interesting services from the perspective of Grid Computing
are Web Services. Web Services use the Internet as the communication medium and
are defined based on open Internet-based standards (Papazoglou et al. 2007). The
relevant standards for Web Services are:
