The Architecture Of Cloud Computing: Cloud architecture, the systems architecture of the software systems involved in the delivery of cloud computing, typically involves multiple cloud components communicating with each other over a loose coupling mechanism such as a messaging queue.
Elastic provision implies intelligence in the use of tight or loose coupling as applied to mechanisms such as these and others.
Cloud computing can be divided into three service models:
Software as a Service (SaaS)
Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). An agency may procure any combination of these service models depending on their particular needs.
Software as a Service (SaaS)
Software as a Service is a delivery model where the software and the associated data is hosted in a cloud environment by a third party such as a cloud service provider (CSP).
Typically the user, such as a staff member in an agency, accesses the software on demand using a browser on a computer or mobile device.
The agency does not buy the software. Instead the CSP licenses the SaaS to the agency, which then enables multiple users to access the software.
Platform as a Service (PaaS) Platform as a Service is a delivery model where a CSP provides an online software development platform for an organization such as an agency.
The agency’s developers use the CSP’s computing environments, tools, and libraries to create, test, manage, and host software applications.
By moving the entire development platform to the CSP, agencies can lessen the cost and management burden of application development.
Infrastructure as a Service (IaaS)
Infrastructure as a Service is a delivery model where CSPs provide the necessary hardware and software upon which a customer can build a customized computing environment.
The CSP typically provides an unmanaged environment that enable the customer, such as an agency, to have any “guest” resources it needs installed: operating systems, software bundles, storage capabilities, etc.
The agency retains full control of the computing environment and is responsible for configuring and maintaining the guest operating systems and associated applications and resources.
The CSP, however, is responsible for maintaining all of the physical equipment.
DEPLOYMENT MODELS
Businesses can choose to deploy applications on Public, Private, Hybrid clouds or the newer Community Cloud.
Here are some fundamentals of each to help with the decision-making process.
Public Cloud
A service provider who hosts the cloud infrastructure makes public clouds available to the general public.
Generally, public cloud providers like Amazon AWS, Microsoft and Google own and operate the infrastructure and offer access over the Internet.
With this model, customers have no visibility or control over where the infrastructure is located.
It is important to note that all customers on public clouds share the same infrastructure pool with limited configuration, security protections and availability variances.
Private Cloud
Private cloud is cloud infrastructure dedicated to a particular organization.
Private clouds allow businesses to host applications in the cloud, while addressing concerns regarding data security and control, which is often lacking in a public cloud environment.
It is not shared with other organizations, whether managed internally or by a third-party, and it can be hosted internally or externally.
Hybrid Cloud
Hybrid Clouds are a composition of two or more clouds (private, community or public) that remain unique entities but are bound together offering the advantages of multiple deployment models.
In a hybrid cloud, you can leverage third party cloud providers in either a full or partial manner; increasing the flexibility of computing.
Augmenting a traditional private cloud with the resources of a public cloud can be used to manage any unexpected surges in workload. read full pdf here
