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Cloud Computing by James F. Ransome, John W. Rittinghouse

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29
Chapter 2
Web Services Delivered
from the Cloud
2.1 Chapter Overview
In this chapter we will examine some of the web services delivered from the
cloud. We will take a look at Communication-as-a-Service (CaaS) and
explain some of the advantages of using CaaS. Infrastructure is also a service
in cloud land, and there are many variants on how infrastructure is managed
in cloud environments. When vendors outsource Infrastructure-as-a-Service
(IaaS), it relies heavily on modern on-demand computing technology and
high-speed networking. We will look at some vendors who provide Soft-
ware-as-a-Service (SaaS), such as Amazon.com with their elastic cloud plat-
form, and foray into the implementation issues, the characteristics, benefits,
and architectural maturity level of the service. Outsourced hardware envi-
ronments (called platforms) are available as Platforms-as-a-Service (PaaS),
and we will look at Mosso (Rackspace) and examine key characteristics of
their PaaS implementation.
As technology migrates from the traditional on-premise model to the
new cloud model, service offerings evolve almost daily. Our intent in this
chapter is to provide some basic exposure to where the field is currently
from the perspective of the technology and give you a feel for where it will
be in the not-too-distant future.
Web service offerings often have a number of common characteristics,
such as a low barrier to entry, where services are offered specifically for con-
sumers and small business entities. Often, little or no capital expenditure for
infrastructure is required from the customer. While massive scalability is
common with these types of offerings, it not always necessary. Many cloud
vendors have yet to achieve massive scalability because their user base gener-
ally does not require it. Multitenancy enables cost and resource sharing
across the (often vast) user base. Finally, device and location independence
enables users to access systems regardless of where they are or what device
Chap2.fm Page 29 Friday, May 22, 2009 11:24 AM
30 Cloud Computing
they are using. Now, let’s examine some of the more common web service
offerings.
2.2 Communication-as-a-Service (CaaS)
CaaS is an outsourced enterprise communications solution. Providers of
this type of cloud-based solution (known as CaaS vendors) are responsible
for the management of hardware and software required for delivering Voice
over IP (VoIP) services, Instant Messaging (IM), and video conferencing
capabilities to their customers. This model began its evolutionary process
from within the telecommunications (Telco) industry, not unlike how the
SaaS model arose from the software delivery services sector. CaaS vendors
are responsible for all of the hardware and software management consumed
by their user base. CaaS vendors typically offer guaranteed quality of service
(QoS) under a service-level agreement (SLA).
A CaaS model allows a CaaS provider’s business customers to selectively
deploy communications features and services throughout their company on
a pay-as-you-go basis for service(s) used. CaaS is designed on a utility-like
pricing model that provides users with comprehensive, flexible, and (usu-
ally) simple-to-understand service plans. According to Gartner,
1
the CaaS
market is expected to total $2.3 billion in 2011, representing a compound
annual growth rate of more than 105% for the period.
CaaS service offerings are often bundled and may include integrated
access to traditional voice (or VoIP) and data, advanced unified communi-
cations functionality such as video calling, web collaboration, chat, real-
time presence and unified messaging, a handset, local and long-distance
voice services, voice mail, advanced calling features (such as caller ID, three-
way and conference calling, etc.) and advanced PBX functionality. A CaaS
solution includes redundant switching, network, POP and circuit diversity,
customer premises equipment redundancy, and WAN fail-over that specifi-
cally addresses the needs of their customers. All VoIP transport components
are located in geographically diverse, secure data centers for high availability
and survivability.
CaaS offers flexibility and scalability that small and medium-sized busi-
ness might not otherwise be able to afford. CaaS service providers are usu-
ally prepared to handle peak loads for their customers by providing services
1. Gartner Press Release, “Gartner Forecasts Worldwide Communications-as-a-Service Reve-
nue to Total $252 Million in 2007,August 2007, retrieved 13 Jan 2009.
Chap2.fm Page 30 Friday, May 22, 2009 11:24 AM

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