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Written by Administrator
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Wednesday, 02 September 2009 03:54 |
Cloud Computing - A brief IntrductionIt is a style of computing in which dynamically scalable and often virtualized resources are provided as a service over the Internet.
Users need not have knowledge of, expertise in, or control over the technology infrastructure in the "cloud" that supports them.
The concept generally incorporates combinations of the following:
- Infrastructure as a service (IaaS)
- Platform as a service (PaaS)
- Software as a service (SaaS)
Cloud computing services often provide common business applications online that are accessed from a web browser, while the software and data are stored on the servers.
The term cloud is used as a metaphor for the Internet, based on how the Internet is depicted in computer network diagrams and is an abstraction for the complex infrastructure it conceals.
Cloud computing is often related and compared (but actually not the same) to grid computing, utility computing and autonomic computing. Indeed most of the present cloud computing deployments use or have the characteristics of above three.
Cloud computing users can avoid capital expenditure (CapEx) on hardware, software, and services when they pay a provider only for what they use. Consumption is usually billed on a utility (e.g. resources consumed, like electricity) or subscription (e.g. time based, like a newspaper) basis with little or no upfront cost. Other benefits of this time sharing style approach are low barriers to entry, shared infrastructure and costs, low management overhead, and immediate access to a broad range of applications. Users can generally terminate the contract at any time (thereby avoiding return on investment risk and uncertainty) and the services are often covered by service level agreements (SLAs) with financial penalties.
The majority of cloud computing infrastructure, as of 2009, consists of reliable services delivered through data centers and built on servers with different levels of virtualization technologies. The services are accessible anywhere that provides access to networking infrastructure. Open standards are critical to the growth of cloud computing, and open source software has provided the foundation for many cloud computing implementations.
While discussing cloud computing, we look at three possible types or variations of Clouds, i.e. public, hybrid and Private cloud.
- Public cloud or external cloud describes cloud computing in the traditional mainstream sense, whereby resources are dynamically provisioned on a fine-grained, self-service basis over the Internet, via web applications/web services, from an off-site third-party provider who shares resources and bills on a fine-grained utility computing basis.
- A hybrid cloud environment consisting of multiple internal and/or external providers "will be typical for most enterprises".
- Private cloud and internal cloud are newly coined terms used to describe offerings that emulate cloud computing on private networks. These (typically virtualisation automation) products claim to "deliver some benefits of cloud computing without the pitfalls", capitalising on data security, corporate governance, and reliability concerns. They have been criticized on the basis that users still have to buy, build, and manage IT resources and as such do not benefit from lower up-front capital costs and less hands-on management, essentially lacking the economic model that makes cloud computing such an intriguing concept at first place.
Cloud Computing development has been assisted by a number of existing, typically lightweight, open standards, including:
- Application
- Communications (HTTP, XMPP)
- Security (OAuth, OpenID, SSL/TLS)
- Syndication (Atom)
- Client
- Browsers (AJAX)
- Offline (HTML 5)
- Implementations
- Platform
- Service
- Data (XML, JSON)
- Web Services (REST)
- Storage
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Last Updated on Thursday, 03 September 2009 05:45 |
