54 Cloud Computing
format of the data being recorded and conveyed is consistent, compatible,
and accurate. By placing the responsibility for an application onto the door-
step of a SaaS provider, enterprises can reduce administration and manage-
ment burdens they would otherwise have for their own corporate
applications. SaaS also helps to increase the availability of applications to
global locations. SaaS also ensures that all application transactions are
logged for compliance purposes. The benefits of SaaS to the customer are
very clear:
Streamlined administration
Automated update and patch management services
Data compatibility across the enterprise (all users have the same
version of software)
Facilitated, enterprise-wide collaboration
Global accessibility
As we have pointed out previously, server virtualization can be used in
SaaS architectures, either in place of or in addition to multitenancy. A major
benefit of platform virtualization is that it can increase a system’s capacity
without any need for additional programming. Conversely, a huge amount
of programming may be required in order to construct more efficient, mul-
titenant applications. The effect of combining multitenancy and platform
virtualization into a SaaS solution provides greater flexibility and perfor-
mance to the end user. In this chapter, we have discussed how the comput-
ing world has moved from stand-alone, dedicated computing to client/
network computing and on into the cloud for remote computing. The
advent of web-based services has given rise to a variety of service offerings,
sometimes known collectively as XaaS. We covered these service models,
focusing on the type of service provided to the customer (i.e., communica-
tions, infrastructure, monitoring, outsourced platforms, and software). In
the next chapter, we will take a look at what is required from the service
provider’s perspective to make these services available.
2.7 Chapter Summary
In this chapter we have examined the various types of web services deliv-
ered from the cloud. Having the ability to leverage reusable software com-
ponents across a network has great appeal to implementors. Today, the
Chap2.fm Page 54 Friday, May 22, 2009 11:24 AM
Chapter Summary 55
most common and successful example of cloud computing is SaaS, but
other functions, including communication, infrastructure, and platforms,
are also core components of cloud computing. Because of the extremely
low barriers to entry, offerings have been made available to consumers and
small businesses as well as mid-sized and large enterprises. This is a key dif-
ferentiator from many service-oriented architecture (SAO) offerings, which
will be covered next.
In the next chapter we will learn how companies build highly auto-
mated private cloud networks that can be managed from a single point. We
will discuss how server and storage virtualization is used across distributed
computing resources. We will describe in basic terms how cloud infrastruc-
ture is built. We will provide an overview of the basic approach to SOA as it
applies to data center design. And we will examine the role and use of open
source software in data centers. Understanding the use and importance of
collaboration technologies in cloud computing architectures is fundamental
to understanding how requirements of the cloud have evolved.
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