The Cloud

What is the cloud?

Terms and general.
Currently there are many different terms and descriptions that define what is cloud or cloud computing. Some say it is the “delivery of computing as a service”, others say it is “processing data in a expandable environment. I like the definition that cloud servers are a way to get “flexible resources as they are required”.
Cloud computing is a way to access computers and their functionality via the Internet or a local area network. Access to the cloud come through a set of web services that manage a pool of computing resources (i.e., machines, network, storage, operating systems, application development environments, application programs). A fraction of the resources in the pool is dedicated to the user until he or she releases them. It is called “cloud computing” because the user cannot actually see or specify the physical location and organization of the equipment hosting the resources they are allowed to use. The resources are drawn from a “cloud”of resources which are used and then returned to the cloud when they are released. A “cloud” is a set of machines and web services that implement cloud computing.

cloud styles

IaaS
IaaS (Infrastructure as a Service) style clouds provide access to collections of virtualized computer hardware resources, including machines, network, and storage. Users assemble their own virtual cluster on which they are responsible for installing, maintaining, and executing their own software stack.

PaaS
PaaS (Platform as a Service) style clouds provide access to a programming or runtime environment with scalable computer and data structures embedded in it. Users develop and execute their own applications within an environment offered by the service provider.

SaaS
SaaS (Software as a Service) referred to as “Software on Demand” style clouds deliver access to collections of software application programs. Providers offer users access to specific application programs controlled and executed on the provider’s infrastructure.

Cloud Types

Public cloud
Public clouds provide access to computing resources for the general public over the Internet. The public cloud provider allows customers to self-provision resources typically via a web service interface.  Public clouds offer access to pools of scalable resources on a temporary rent as you go basis without the need for capital investment in data center infrastructure.

Private cloud
Private clouds give users immediate access to computing resources hosted within an organization’s infrastructure. Users self-provision and scale collections of resources drawn from the private cloud, just as with a public cloud. However, because it is deployed within the organization’s existing data center, and behind the organization’s firewall, a private cloud is subject to the organization’s physical, electronic, and procedural security measures and thus offers a higher degree of security over sensitive code and data. In addition, private clouds consolidate and optimize the performance of physical hardware through virtualization. Since you use your current data center infrastructure you have a better idea on how the resources are being utilized.  The cloud systems I will discuss are of this type.

Hybrid cloud
A hybrid cloud combines computing resources and draws from one or more public clouds and one or more private