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原帖由 xiaofeiwen 于 2009-9-11 11:05 发表 
感觉上要架设的话需要里面有点东西才行，不然空空的也就吸引不起兴趣去研究了。就说P2P我们要在里面放点什么呢？电影？连续剧？好像每个人的需求不同，那就需要一个大容量的空间了。不过先加起来再说，有了实质的东西 ...
Cloud computing is a general term for anything that involvesdelivering hosted services over the Internet. These services arebroadly divided into three categories: Infrastructure-as-a-Service(IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). The name cloud computing was inspired by the cloud symbol that's often used to represent the Internet in flow charts and diagrams.
Acloud service has three distinct characteristics that differentiate itfrom traditional hosting. It is sold on demand, typically by the minuteor the hour; it is elastic -- a user can have as much or as little of aservice as they want at any given time; and the service is fullymanaged by the provider (the consumer needs nothing but a personalcomputer and Internet access). Significant innovations invirtualization and distributed computing, as well as improved access tohigh-speed Internet and a weak economy, have accelerated interest incloud computing.
A cloud can be private or public. A public cloud sells services to anyone on the Internet. (Currently, Amazon Web Services is the largest public cloud provider.) A private cloudis a proprietary network or a data center that supplies hosted servicesto a limited number of people. When a service provider uses publiccloud resources to create their private cloud, the result is called avirtual private cloud. Private or public, the goal of cloud computingis to provide easy, scalable access to computing resources and ITservices.
Infrastructure-as-a-Service like Amazon Web Services provides virtual server instances with unique IP addresses and blocks of storage on demand. Customers use the provider's application program interface (API)to start, stop, access and configure their virtual servers and storage.In the enterprise, cloud computing allows a company to pay for only asmuch capacity as is needed, and bring more online as soon as required.Because this pay-for-what-you-use model resembles the way electricity,fuel and water are consumed, it's sometimes referred to as utilitycomputing.
Platform-as-a-service inthe cloud is defined as a set of software and product development toolshosted on the provider's infrastructure. Developers create applicationson the provider's platform over the Internet. PaaS providers may useAPIs, website portals or gatewaysoftware installed on the customer's computer. Force.com, (an outgrowthof Salesforce.com) and GoogleApps are examples of PaaS. Developers needto know that currently, there are not standards for interoperability ordata portability in the cloud. Some providers will not allow softwarecreated by their customers to be moved off the provider's platform.
Inthe software-as-a-service cloud model, the vendor supplies the hardwareinfrastructure, the software product and interacts with the userthrough a front-end portal. SaaS is a very broad market. Services canbe anything from Web-based email to inventory control and databaseprocessing. Because the service provider hosts both the application andthe data, the end user is free to use the service from anywhere. |
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发表于 2009-9-10 14:47:57
