What is the cloud ? IT as a service Cloud allows access to services without user technical knowledge or control of supporting infrastructure Best described in terms of what happened to mechanical power over 100 yrs ago Now computers are simple devices connected to the larger cloud Data processing, storage and software applications that used to run locally are now being supplied by big central computing stations. They're becoming, in essence, computing utilities. What is Cloud Computing?

Cloud Computing Cloud computing is Internet-based computing, whereby shared resources, software and information are provided to consumers on-demand. It describes a new consumption and delivery model for IT services based on the Internet and typically involves the provisioning of dynamically scalable and often virtualized resources as-a-service over the Internet.

It is sold on demand, typically by the minute or the hour; It is elastic -- a user can have as much or as little of a service as they want at any given time; The service is fully managed by the provider (the consumer needs nothing but a personal computer and Internet access). Three distinct characteristics

IaaS Infrastructure as a Service PaaS Platform as a Service SaaS Software as a Service Three Layers of Cloud Computing

SaaS Software as a Service Software as a service (SaaS), sometimes referred to as "on-demand software," is a software delivery model in which software and its associated data are hosted centrally (typically in the (Internet) cloud) and are typically accessed by users using a thin client, normally using a web browser over the Internet.

Features No hardware or software to manage Pay Per use Service delivered through a browser Used by consume r SaaS

Examples Gmail Facebook Commercial Services: Salesforce.com cloud SaaS

PaaS Platform as a Service Platform as a Service (PaaS) refers to an environment for software development, storage and hosting delivered as-a-service over the Internet. It facilitates the development and deployment of applications without the cost and complexity of buying, managing and configuring the underlying hardware, middleware and software layers

Features Requires no up-front investments. Instant Scalability Enhanced productivity Used by Developer PaaS

Examples Facebook API Google App Engine Windows Azure PaaS

IaaS Infrastructure as a Service Infrastructure as a Service (IaaS) delivers a computing infrastructure, typically a virtualization environment, as-a-service. Rather than purchasing & configuring servers, storage and network equipment, the client can utilize these resources as a fully outsourced service.The service is typically billed on a utility computing basis and the amount of resources consumed (and therefore the cost) will typically reflect the level of activity.

Computer infrastructure delivery model Access to infrastructure stack: –Full OS access –Firewalls –Routers –Load balancing IaaS

Features Pay per use Instant Scalability Security Reliability APIs IaaS

Examples Flexiscale AWS: EC2 IaaS

Cloud Economics Multi-tenented Virtualisation lowers costs by increasing utilisation Economies of scale afforded by technology Automated update policy IaaS PaaS SaaS

Risks Security Downtime Access Dependency Interoperability IaaS PaaS SaaS

Deployment models -Public cloud -Private cloud -Community cloud -Hybrid cloud IaaS PaaS SaaS