Wednesday, March 2, 2011

What is the cloud?

An approach to computing that's about internet scale and connecting to a variety of devices and
endpoints, According to Microsoft cloud is simply an approach to computing that enables applications
to be delivered at scale for a variety of workloads and client devices.

Cloud Services

it's important to understand how to talk about our Cloud Services offerings.
•There is a lot of confusion in the industry when it comes to the cloud.  
It's important that you understand both what is happening in the industry and how we think about the cloud. 
This is the most commonly used taxonomy for differentiating between types of cloud services.
•The industry has defined three categories of services:
•IaaS – a set of infrastructure level capabilities such as an operating system, network connectivity, etc. that are
delivered as pay for use services and can be used to host applications. 
•PaaS – higher level sets of functionality that are delivered as consumable services for developers who are
building applications. 
PaaS is about abstracting developers from the underlying infrastructure to enable
applications to quickly be composed.
•SaaS – applications that are delivered using a service delivery model where organizations can simply consume
and use the application.  Typically an organization would pay for the use of the application or the application
could be monetized through ad revenue. 
It is important to note that these 3 types of services may exist independently of one another or combined with one
SaaS offerings needn't be developed upon PaaS offerings although solutions built on PaaS offerings are often
delivered as
PaaS offerings also needn't expose IaaS and there's more to PaaS than just running platforms on IaaS.
Differences and relationship between IaaS, PaaS, and SaaS

Packaged Software
With packaged software a customer would be responsible for managing the entire stack – ranging from the
network connectivity to the applications. 
With Infrastructure as a Service, the lower levels of the stack are managed by a vendor.  Some of these
components can be provided by traditional
hosters – in fact most of them have moved to having a
virtualized offering. 
Very few actually provide an OS
The customer is still responsible for managing the OS through the Applications. 
For the developer, an obvious benefit with IaaS is that it frees the developer from many concerns when
provisioning physical or virtual machines.
This was one of the earliest and primary use cases for Amazon Web Services Elastic Cloud Compute (EC2).
Developers were able to readily provision virtual machines (AMIs) on EC2, develop and test solutions and,
often, run the results 'in production'.
The only requirement was a credit card to pay for the services.
With Platform as a Service, everything from the network connectivity through the runtime is provided and
managed by the platform vendor. 
The Windows Azure Platform best fits in this category today. 
In fact because we don't provide access to the underlying virtualization or operating system today, we're
often referred to as not providing
•PaaS offerings further reduce the developer burden by additionally supporting the platform runtime and
related application services.
With PaaS, the developer can, almost immediately, begin creating the business logic for an application.
Potentially, the increases in productivity are considerable and, because the hardware and operational
aspects of the cloud platform are also managed by the cloud platform provider, applications can quickly
be taken from an idea to reality very quickly.
•Finally, with SaaS, a vendor provides the application and abstracts you from all of the underlying components.  

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