"Cloud Computing"

No need to install S/W in our PC. S/W producer already installed on his or her server so user can access resources from the cloud at any time, from any location via the Internet by registration. If you build a Enterprise System by using Cloud, you can save amount of money from developing to until maintenance. Cloud Computing is rally a culmination of many technologies such as grid computing, utility computing, SLA (Service Level Agreements), SOA (Service Oriented Architecture), Web 2.0 and other technologies. It has common cloud characteristics and five essential cloud characteristics. Five essential cloud characteristics are (1) On-demand self-service (2) Broad network access (3) Location independence (4) Rapid elasticity (5) Measured service. Can be visualized consisting of three sections: Cloud Application also called SaaS (Software as a Service), Cloud Platform also called PaaS (Platform as a Service) and Cloud Infrastructure also called IaaS (Infrastructure as a Service).

Cloud application (services on demand) eliminates to install and run application on the customer's own computer. If you have suitable internet connection and a standard browser can access a cloud application. It include enterprise software such as web-based email like that Gmail.
Examples: Google Apps (Google Docs, Google Calendar, Google Video, etc.), Flickr, CRM (Customer Relationship Management), Payroll, IBM Lotus Live

Cloud platform (resources on demand) allow software developers to write applications and deploy them directly to the Cloud.
Examples: GAE (Google App Engine), Force.com, Mosso
GAE is use Python and Java but can also run other languages such as Rails, JRuby. SalesForce platform use Apex and Java.

Cloud infrastructure includes servers, networks and other hardware appliances. Use large data centers and powerful servers that host Web applications and Web services.
Examples: Amazon Web Services (EC2, S3), Microsoft Azure Platform (Window Azure, SQL Services, .NET Services, Live Services), Rackspace, GoGrid, 3Tera, RightScale, Flexiscale, IBM Blue House, VMWare, Sun Parascale and more.

4 Cloud Deployment Models
(1) Private Cloud (corporate or internal cloud) - Hosted within an organization's firewall
(2) Public Cloud (external cloud) - Hosted on the Internet
(3) Hybrid Cloud - Composition of two or more clouds
(4) Community Cloud - Shared infrastructure for specific community

Cloud Computing is the sum of SaaS and Utility Computing, but does not include Private Clouds. (A Berkeley View of Cloud Computing)

Benefits/ Advantages of Cloud Computing - Reduced Costs (save money), Increased Storage (can store more data than on private computer systems), Highly Automated (no need to worry about keeping S/W up to date), Flexibility (offers much more flexibility than past computing), Allows IT to Shift Focus, Ease of implementation and Access, Scalability, Capacity and Sustainability, Resource Maximization, Collaboration, Customization, H/W and S/W Maintenance, Device and Location Independence, Rapid Innovation, Improved Performance and Reduced S/W Costs.

Disadvantage - Requires a constant Internet connection, Features might be limited, Stored data might not be secure, Stored data can be lost.

What is the difference of ASP and Cloud?

- quite significant, but both are "hosted"
- ASP: single-instance, single-tenant legacy software application
- Cloud: multi-tenancy