Information Technology Reference
In-Depth Information
information, directory, resource management (resource trading, resource alloca-
tion, quality of service) and high-level services/tools for application development,
resource management and scheduling (Buyya et al. 2005). In addition, there is a
need to provide the functionality for brokerage of resources, accounting and billing
purposes. The main functionalities of a Grid middleware are (see also Meliksetian
et al. 2004):
• Virtualization and integration of heterogeneous autonomous resources (Reinefeld
and Schintke 2004)
• Provision of information about resources and their availability (see for example
Boden 2004)
• Flexible and dynamic resource allocation and management (see for example
Boden 2004, Reinefeld and Schintke 2004)
• Brokerage of resources either based on company policies (Next Generation
GRIDs Expert Group 2006) or open markets (Buyya et al. 2005)
• Security and trust (Geiger 2006, Boden 2004). Security includes authentication
(assertion and confirmation of the identity of a user) and authorization (check of
rights to access certain services or data) (Angelis et al. 2004) of users as well as
accountability (see also Boden 2004).
• Management of licences (Geiger 2006)
• Billing and payment (Geiger 2006)
• Delivery of non-trivial Quality of Service (QoS) (Boden 2004)
Given the complex functionalities above, it is obvious that Grid is a complex system
and no single technology constitutes a Grid. For example, according to Smith et al.
(2006), components of the typical service-oriented Grid middleware are: Globus
Toolkit 4.0 (GT4), Tomcat 5.5 and Axis. Each of the three is a large scale software
system encompassing thousands of Java classes. In many cases the necessary func-
tionality is assembled by several software and middleware providers. This means
that building and providing a Grid requires a functioning ecosystem of complemen-
tary services from software providers and integrators (see also chapter 6). It is not
possible to purchase a Grid off the shelf (Castro-Leon and Munter 2005).
3.4 Potential Advantages and Risks of Grid Computing
Grid Computing provides advantages and opportunities for companies on two levels:
on the IT management level, it enables a more efficient utilization of IT resources;
on the business level, it increases efficiency, agility and flexibility.
The major potential advantages of Grid Computing for an improved manage-
ment of IT in companies can be summarized as follows:
• Grids harness heterogeneous systems together into a single large computer,
and hence, can apply greater computational power to a task (Bourbonnais et
al. 2004) and enable greater utilization of available infrastructure (McKinsey
2004). In particular, with Grid Computing existing underutilized resources can
be exploited better (Berstis 2002).
