Cloud Architecture

Chapter 2

SPI Model

• Cloud Computing Classification Model – SPI - SaaS: (Software as a Service) - PaaS (Platform as a Service) - IaaS (Infrastructure as a Service)

• Infrastructure services share the physical hardware

• Platform services application framework• Software services share the entire software

stack.

• Amazon Elastic Compute Cloud (EC2) is a classic example of IaaS

• Google App Engine is generally considered to be a PaaS

• Salesforce.com is a well known example of SaaS.

Cloud Delivery Model

• Public Cloud• Private Cloud• Partner Cloud• Community Cloud• Hybrid or Multi-sourced Delivery

• Public cloud: It has large set of the following features: - Off-premise - Elastisity - Flexible billing - Virtualization - Service delivery - Universal access - Simplified management - Affordable resources - Multi-tenancy - Service level management

• Private Cloud: only leverages some of the aspects of cloud computing

- hosted on-premise, - scales “only” into the hundreds or perhaps

thousands of nodes, - connected primarily to the using organization

through private network links. - since all applications and servers are shared

within the corporation the notion of multi-tenancy is minimized.

• Partner Cloud: Large IT providers, such as HP Enterprise Services or IBM Global Services, run data center for operations for large customers

- manage services in their own facilities; - or on customer premises; - or on property of a third party

• Community Cloud: it caters a group of organizations with common set of requirements or objectives.

• The most prominent examplea are government clouds that are open to federal and municipal agencies.

• Hybrid or Multi-sourced delivery:

Cloud and Open Source

• Cloud computing can leverage open source in many ways. - Self-supported Linux is by far the most popular

opernating system from infrastructure servies - Cloud provider often use Xen and KVM for virtualization - Distributed cloud framwworks, such as Hadoop, are

usally open source - Web-based API make the client device less relevant,

which can reduce desktop license fees by adopting Linux, Google Chrome or other open-souce client.

- Many SaaS solutions leverage open-source software, such as SugarCRM