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Where did the term “cloud” come from? Mature mainframers remember the diagrams that people used to show on their overhead projectors where links from computers went into a cloud that represented the telephone system and more links came out to terminals. The “cloud part” came to represent the Internet on numerous PowerPoint slides. Now, that cloud has taken on a life of its own. In fact, if you search the Internet, you’ll find that Feb. 24, 2007 is the day the term “cloud computing” was coined.
Not all clouds are necessarily public clouds. A public cloud would be one that sells services to anyone on the Internet (like Amazon Web services). A private cloud would be used by an organization to supply hosted services to people within the organization. There’s one slight complication to this simple dichotomy: It’s possible for a private cloud to be made available using public cloud resources. The result is referred to as a virtual public cloud.
What is meant by a service? Services can be divided into three categories:
- Infrastructure-as-a-Service (IaaS)
- Platform-as-a-Service (PaaS)
- Software-as-a-Service (SaaS).
These services can be distinguished from traditional hosting because they’re sold on demand; users purchase as much of a service as they want, when they want it. Also, the service is managed by the provider.
The SaaS model involves deploying the software over the Internet. The vendor provides the software, any databases, and the servers it uses. The user accesses the service, usually through a browser. Available services range from invoicing to email to database processing. The user (subscriber) simply pays for what they use. The user could get a similar service from a different provider if they were to choose to do so.
The IaaS model occurs when an organization outsources the equipment it needs for its IT infrastructure, including storage, servers, and networking components. A service provider owns all the hardware and must maintain it. Users are given an IP address and access to the supplier’s API to use their virtual hardware. The advantage of this kind of computing is that organizations pay only for the computing power they use; it also allows them to get more as necessary.
The PaaS model facilitates deployment of applications without a need to purchase and manage the underlying hardware and software. Developers may use APIs or software installed on their computer by the vendor to develop Web applications and services. (A Web application is basically an application accessed over the Internet, or, possibly, an intranet. Web applications are convenient and available through a Web browser client. There’s no need for an organization to continually update its software because the Web application used is always the latest version. The responsibility for updating and testing the Web application lies with the provider.
Gartner Research is a big fan of cloud computing, telling us that: “The use of cloud computing in general has been spreading rapidly over the past few years, as companies look for ways to increase operating efficiency and data security. The cloud industry, which is in its infancy, will generate $3.4 billion in sales this year.” Similarly, Merrill Lynch predicts that by 2011 the cloud computing market will reach $160 billion, including $95 billion in business and productivity applications.
Most industry journals and conferences are focusing on Microsoft’s Windows Azure, an environment for development, service hosting, and service management based on the cloud. It’s designed to allow developers to compute, host, scale, store, and manage the Web applications they create. Windows Azure relies on the global network of Microsoft data centers to offer the services; it lets developers use Microsoft Visual Studio, along with SOAP, REST, XML, and PHP.
Finally, Google has a partnership with VMware to develop a new operating system for the cloud. This partnership is designed to enable users to avoid being tied down to a single supplier by ensuring that applications are portable. Companies will be able to build and maintain their own applications to run in a VMware environment on any infrastructure compatible with Java standards. Google has said it will provide cloud-based database and secure transaction services this year.