Cloud Computing

Cloud computing is a style of computing in which dynamically scalable and often virtualized resources are provided as a service over the Internet. In cloud computing, computing power is available on demand and IT resources are delivered as services.

Five attributes of Cloud Computing
1. It is service-based.
2. It is scalable and elastic. I.e., it is able to add and remove infrastructure as needed.
3. It uses shared infrastructure to build economies of scale.
4. It is metered and users pay according to usage.
5. Most importantly, of course, it uses Internet technologies.

Cloud Computing Architecture
The architecture incorporates combinations of the following:
· Software as a service (SaaS)
· Platform as a service (PaaS)
· Infrastructure as a service (IaaS)

Figure: Cloud compting architecture

SAAS Example:
Salesforce.com (CRM)
e-shop and Resource Datamine (Netedge)
Identity (OAuth, OpenID) , Integration (Amazon Simple Queue Service)
Payments (Amazon Flexible Payments Service, Google Checkout, PayPal)
Mapping (Google Maps, Yahoo! Maps, MapQuest) , Google docs
Search (Alexa, Google Custom Search) and Live chat (LivePerson)


Cloud computing vendors:
Computer hardware (Dell, HP, IBM, and Sun Microsystems)
Storage (3PAR, EMC, Hitachi Data Systems, IBM, Mezeo, NetApp, ParaScale, and Sun Microsystems)
Infrastructure (Cisco Systems, Juniper Networks, and Brocade Communications)
Computer software (3tera, Eucalyptus, g-Eclipse, and Hadoop)
Operating systems (Solaris, AIX, Linux including Novell[81], Red Hat[82], and Ubuntu[83])
Platform virtualization (Citrix, IBM, Linux KVM, Microsoft, Sun xVM, VMware, and Xen)
Wipro, Net Magic, Bharti Airtel.


Source:
1. Wikipedia
2. Dr. Manoj Saxena, Netedge.