Cloud computing is a technology that strives to deliver computing as a service rather than as a product, whereby shared resources, software and information are provided to computers and other devices as a utility over a network(typically the internet). As a metaphor for the internet â€œthe cloudâ€ is a familiar clichÃ© but the meaning gets bigger when combined with â€œcomputingâ€. Some analysts and vendors however define cloud computing narrowly as an updated version of utility computing.
Cloud computing encompasses any subscription-based or pay-per-use service that, in real over the INTERNET, extends ITâ€™s existing capabilities from full blown applications to storage services to spam filtering.
1. Software as a Service (SaaS)
This type of cloud computing uses a multitenant architecture to deliver a single application through the browser to thousands of customers. On the customer side, it means no upfront investment in servers or software licensing; on the provider side with just one app to maintain, costs are low compared to conventional hosting. SaaS is common for HR apps and has even worked its way up the food chain to ERP, with big names such as Workday and has also shown an unpredictable sudden rise in desktop applications such as Google Apps and Zoho Office.
2. Web Services in the Cloud
Closely related to SaaS, web service providers offer APIs that enable developers to exploit functionality over the Internet rather than delivering full-blown applications. Major discrete business service providers such as Strike Iron and Xignite use this method to provide their services over the internet while a full range of APIs is offered by Google Maps, ADP payroll processing, the U.S. Postal Service, Bloomberg and even conventional credit card processing services.
3. Utility Computing
As a primitive idea, this form of cloud computing is getting new life from Amazon.com, Sun, IBM and others who now offer storage and virtual servers that IT can access on demand. Early enterprise adopters mainly use utility computing for supplemental, non-mission critical needs, but one day, they may replace parts of the datacenter. Other providers offer solutions that help IT create virtual datacenters from commodity servers, enabling IT to stitch together memory, I/O, storage and computational capacity as a virtualized resource pool available over the network.
4. Platform as a Service (PaaS)
Another SaaS variation, this form of cloud computing delivers development environment as a service. The applications built by the vendor run on the providerâ€™s infrastructure and are delivered to users via the Internet from the providerâ€™s servers. These services are constrained by the vendorâ€™s design and capabilities like Lego blocks, so you donâ€™t get complete freedom but you do get predictability and pre-integration. For extremely lightweight development, cloud based mashup platforms abound such as Yahoo Pipes or Dapper.net. Coghead, Force.com (by Salesforce.com) and the new Google App Engine also are prime examples of this technology.
5. Managed Service Providers (MSP)