Cloud Computing Support for Construction Collaboration - Mobile and Pervasive Computing in Construction - page 242

the general public and are owned by organizations selling cloud services. Private
clouds are “cloud infrastructures that are operated for an organization. They may be
managed by the organization or a third party and may exist on premise or off premise”
(Mell and Grance, 2011).
According to Armbrust et al., however, cloud computing includes public clouds
but not private clouds:“Cloud Computing refers to both the applications delivered as
services over the Internet and the hardware and systems software in the datacenters
that provide those services.

The datacenter hardware and software is what we will
call a Cloud. When a Cloud is made available in a pay-as-you-go manner to the
general public, we call it a Public Cloud; the service being sold is Utility Computing. We
use the term Private Cloud to refer to internal datacenters of a business or other
organization, not made available to the general public. Thus, Cloud Computing is the
sum of SaaS and Utility Computing, but does not include Private Clouds” (Armbrust
et al., 2009, 2010).
Besides public clouds and private clouds, two more deployment models are
defined by the NIST in the United States. The first model is community clouds,
which are similar to Intranets in concepts:“Community clouds are cloud infra-
structures shared by several organizations to support a specific community that has
shared concerns (e.g. mission, security requirements, policy, and compliance con-
siderations). They may be managed by the organizations or a third party, and may
exist on premise or off premise” (Mell and Grance, 2011). The second model is hybrid
clouds, which are “a composition of two or more clouds (public, private, or
community) that remain unique entities but are bound together.”
In addition, Amazon introduced another deployment model namely “virtual
private clouds” in 2009. A virtual private cloud includes a private, isolated section
of public clouds, as illustrated in Figure 12.2. The isolated section communicates
with internal clouds and/or legacy systems through virtual private network (VPN).
The public cloud providers allow users to control and customize the network
configuration of the public cloud section, such as IP address range, subnets, and
network gateways. Virtual private cloud users can leverage the public cloud
environment while enjoying the security and control of private clouds.

:::

Figure 12.2 Illustration of a virtual private cloud