CLOUD COMPUTING CORE
CONCEPTS
In the cloud computing model, computing power, software,
storage services, and platforms are delivered on demand to external customers
over the internet. The access that this
technology provides to resources and services can be scaled up or down to meet
demand. Cloud computing providers typically charge customers on a pay-per-use
model.
PERSPECTIVES ON CLOUD
COMPUTING
The types of cloud computing technology can be viewed from
two perspectives: capability and access. In this section, we look at three
types based on capabilities provided and two based on who can access resources
(figure 1).
Figure 1: Cloud Computing Types Based on Capability and Access
Examples on types of
Cloud Computing
One type of cloud computing capability is called Software-as-a-Service (SaaS). SaaS
focuses on providing users with business-specific capabilities, such as e-mail
or customer management. In SaaS, organizations and developers can use the
business-specific capabilities developed by third parties in the “cloud.” Some
examples of SaaS providers are:
Google Apps: provides web-based office tools such as e-mail,
calendar, and document management
salesforce.com: provides a full customer relationship
management (CRM)6 application
zoho.com: provides a large suite of web-based applications,
mostly for enterprise use
A second type of cloud computing capability is known as Infrastructure-as-a-Service (IaaS).
This capability type provides mainly computational infrastructure available
over the internet (e.g., compute cycles or storage). IaaS allows organi-zations
and developers to extend their IT infrastructure on an on-demand basis. Some
examples of IaaS providers are:
Amazon Elastic Compute Cloud (EC2): provides users with a
special virtual machine (AMI) that can be deployed and run on the EC2
infra-structure
Amazon Simple Storage Solution (S3): provides users with
access to dynamically scalable storage resources
GoGrid: provides users with access to dynamically scalable
computing and storage resources, as well as dedicated servers
IBM Computing on Demand (CoD): provides users with access to
high-ly configurable servers plus value-added services such as data storage
Microsoft Live Mesh: provides users with access to a
distributed file system; targeted at individual use
Rackspace Cloud: provides users with access to dynamically
scalable computing and storage resources, as well as third-party cloud applications
and tools
The third and final type of cloud computing capability is Platform-as-a-Service (PaaS). In this
type, application development platforms allow users to leverage the resources
of established organizations to create and host applications of a larger scale
than an individual or small business would be able to handle. Some PaaS examples include:
Akamai EdgePlatform: provides a large distributed computing
platform on which organizations can deploy their web applications; has a large
focus on analysis and monitoring
Force.com: from salesforce.com (an SaaS provider), provides
users with a platform to build and run applications and components bought from
AppExchange or custom applications
Google App Engine: provides users with a complete
development stack and allows them to run their applications on Google’s
infrastructure
Microsoft Azure Services Platform: provides users with
on-demand compute and storage services as well as a development platform based
on Windows Azure
Yahoo! Open Strategy (Y!OS): provides users with a means of
develop-ing web applications on top of the existing Yahoo! platform and in
doing so leveraging a significant portion of the Yahoo! Resources
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