A narrow sense, cloud computing
Cloud computing refers to a narrow IT infrastructure, delivery and usage patterns, refers to the network to on-demand, easy way to expand access to the necessary resources (hardware, platforms, software). Provide resources to the network is called "cloud." "Cloud" in the resources in the user appears to be an infinitely expandable, and can readily access, on-demand use, at any time expansion, pay-per-use. This feature is often referred to as the use of IT, like electricity and water infrastructure.

2, generalized cloud computing
Cloud computing refers to the broad service delivery and usage patterns, refers to the network to on-demand, easy way to obtain the necessary expansion of services. This service can be IT and software, Internet-related, it can be any other services.

Explained:

This resource pool is called "cloud." "Cloud" is the number of self-maintenance and management of virtual computing resources, usually for a number of large-scale server clusters, including computing servers, storage servers, broadband resources and so forth. Cloud computing all the computing resources together by the software automatically manages, without any human involvement. This allows application providers do not need to worry about the details of complicated, will be more focused on their own business, there are conducive to innovation and lower costs.


For example, some people I called: It is like a generator from the old model to a single centralized power plant model. It means that computing power can also be carried out in circulation as a commodity, like gas, electricity and water, as access to convenient and inexpensive. The biggest difference is that it is transmitted through the Internet.


Cloud computing is parallel computing (Parallel Computing), Distributed Computing (Distributed Computing) and grid computing (Grid Computing) development, or those of the commercial realization of the concept of computer science. Cloud computing is virtualization (Virtualization), utility computing (Utility Computing), IaaS (Infrastructure as a service), PaaS (Platform as a service), SaaS (software as a service), etc., and jumped the evolution of the concept of mixed results.


In general, cloud computing is grid computing can be counted as a commercial version of evolution. As early as 2002, China Liu Peng on the idea that traditional grid computing, there is no practical issue, the concept of calculating the pool: "to spread throughout the high-performance computers connected by high-speed network, using specially designed middleware software organically bonding together to scientists around the Web interface to accept the calculation made by the request, and to allocate it to the appropriate nodes to run. computing pool can greatly enhance the quality of service and utilization of resources, while avoiding the inter-node partitioning the application proceedings brought by inefficiency and complexity can be achieved under the present conditions in the practical requirements. "If the text in the" high-performance computers "into the" server farms "will" scientific workers "replaced by" commercial users "with the current cloud computing is very close.


Cloud computing has the following characteristics:


(1) very large scale. "Cloud" has a considerable scale, Google cloud computing already has more than 100 million servers, Amazon, IBM, Microsoft, Yahoo, etc. "cloud" both have hundreds of thousands of servers. Private companies typically have hundreds of thousands of cloud servers. "Cloud" can give users an unprecedented computing power.


(2) virtualization. Cloud computing support for users in any location, using a variety of terminal access to application services. The requested resources from the "cloud" rather than a fixed physical entity. Applied in the "cloud" somewhere in running, but in fact the user without having to know or worry about the specific location of running applications. Only need a laptop or a cell phone, it can be achieved through the Web services we need everything, even including the super-computing such a task.


(Three) high reliability. "Cloud" over the use of the data a copy of fault-tolerance, computing nodes are interchangeable with the structure and other measures to ensure the service reliability, the use of cloud computing and reliable than using the local computer.


(4) versatility. Cloud computing is not for a specific application, in the "cloud" can be constructed under the support of the application of the ever-changing, with a "cloud" can simultaneously support different applications running.


(5) High scalability. "Cloud" the size of dynamically scalable to meet the growing size of applications and user needs.


(6) on-demand services. "Cloud" is a huge resource pool, you demand to buy; cloud can be like running water, electricity, gas as billing.


(7) is extremely cheap. As the "cloud" of special fault-tolerance measures for extremely low-cost nodes can be used to form the clouds, "clouds" automated centralized management of large amounts of business without the burden of increasingly high cost of data center management, "clouds" universal nature of the resource utilization Compared with traditional systems to increase substantially so that users can fully enjoy the "cloud" of low-cost advantages, often as long as a few hundred dollars to spend a few days time, will be able to complete the previously required tens of thousands of U.S. dollars, a few months time to complete the task.


Cloud computing can be completely changed people's future life, but must also take environmental issues seriously, so as to truly contribute to human progress, rather than simply upgrade their technology.

"Cloud computing" era
Today's society, PC is still our daily work life in the central tool - we use the PC processing documents, store information, via e-mail or U disk to share information with others. If the PC hard drive is broken, we will because the information is lost and helpless. In the "cloud computing" era, "cloud" will for us to do storage and computing work. "Cloud" is a computer cluster, each group includes hundreds of thousands of units, or even millions of computers. "Cloud" the further advantage, in which computers can be updated to ensure the "cloud" longevity. Google there are several such "cloud" and other IT giants such as Microsoft, Yahoo, Amazon (Amazon) also have or are in the construction of such a "cloud." By then, we only need a computer with Internet access, without concern to what occurred in the storage or computing Duo "cloud", but if there is a need, we can use any device in any location, such as computers, mobile phones, fast calculation of and find the information. We no longer have to worry about data loss.


Xuemei joined Google in the Valley, she found that this type of concept has been in practice. Google's technology that allows hundreds of thousands of computers together to play a role, form a powerful data centers. Google China's former CEO Kai-fu Lee had accepted "financial" press interview, said, Google's competitive edge lies in the true of these "clouds", and they let Google have a unique global data storage and computing capacity. Google began as, and does not deliberately go for "cloud computing" and "lattice calculation" and so on. However, as a search engine, Google objectively the need to have these "clouds." In fact, Yahoo's search is also taking advantage of "cloud computing." Cloud computing is an emerging method of shared infrastructure, it can be a huge pool of connected systems in order to provide a variety of IT services. Many factors contributed to the demand for such environments, including connected devices, real-time data streams, SOA adoption and search, open collaboration, social networking and mobile commerce applications such as the rapid growth of Web 2.0. In addition, the number of components to enhance performance also substantial increase in the scale of IT environments, thus further strengthened by a unified cloud management needs.


Cloud computing + always-On device was named "25 years, the top ten most influential IT technology portfolio," [4]


"New York Times": cloud computing in the end mean?


Cloud computing is being widely popular saying, Gartner senior analyst Ben Pring, commented: "It is becoming a popular word." But the problem is that everyone seems to cloud computing for the understanding of different. As a metaphor of the Internet "cloud" is very easy to understand. But once with the "calculated" link on the expansion of its meaning, and it began to become blurred. Some analysts and companies is defined as the calculation of cloud computing is only an upgraded version - available on the Internet is basically a number of virtual servers. Others put the definition of cloud computing more broadly, they believe a user outside the firewall to protect consumer that everything in the "cloud" at home.


Cloud computing has been concern in the IT industry, in the end one considers what is required, people need to find a way to be able to no new investment, new human and new software, an increase in the ability and capacity of the Internet. Precisely the cloud computing offers this possibility. Cloud computing today is at a beginner's stage, large and small companies with a wide range of cloud computing services, from software applications to network storage and then to mail filtering. These companies are part of the infrastructure provider, the other part is like Salesforce.com sort of SAAS (software as a service) provider. Today the main achievement is that Internet-based personal services, but the cloud computing aggregation and integration are still arising.

Several major forms of cloud computing
InfoWorld Web site with dozens of companies, analysts and IT users to discuss cloud computing out of several major forms:


1.SAAS (Software as a Service)


This type of cloud computing through the browser to pass the procedure hundreds of thousands of users. The user's eyes, this will save on the server and software licensing costs; from the supplier point of view, it is not only the need to maintain a program enough, this can reduce costs. Salesforce.com is by far the best known of such services company. SAAS in human resources management procedures and the more commonly used ERP. Google Apps and Zoho Office are also similar services


2. Practical Computation (Utility Computing)


This idea has been a long time ago, but until recently at Amazon.com, Sun, IBM and other providers to storage services and virtual servers in the new company. This cloud computing is for the IT industry to create a virtual data center makes it able to memory, I / O devices, storage and computing power together into a virtual pool of resources to provide services for the entire network.


3. Network Services


Close ties with the SAAS, Internet service providers are able to provide API for developers to develop more Internet-based applications, rather than providing stand-alone program.


4. Platform as a service


Another SAAS, this form of cloud computing to the development environment as a service to provide. You can use the equipment brokers to develop their own procedures and transmitted via the Internet and its server users.


5.MSP (Management Service Provider)


The oldest use of cloud computing is one. This application is for the IT industry, more, rather than end users, commonly used in e-mail virus scanning, process monitoring and more.


6. Business Service Platform


SAAS and the MSP hybrid applications, the class cloud computing for the interaction between users and providers, providing a platform. Personal expenses such as user management system that can be based on the user settings to manage its expenses and to coordinate their subscription services.


7. Internet Integration


Will provide similar services on the Internet companies that integrate so that users can more easily compare and choose their own service provider