什么是云计算

What is cloud computing

Cloud computing is a general term for anything that involves deliveringhosted services over the Internet. These services are broadly 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 representthe Internet in flowcharts and diagrams.

云计算是指因特网上包括大部分服务器提供托管服务的统称。这些服务明显可以分为三类：lass(基础设施服务),PaaS(平台服务)和SaaS(软件服务).

云计算名称的灵感来源于经常被用于表现因特网的流程作业图的绘制的云形标志(象征)。

A cloud service has three distinct characteristics that differentiate it from traditional hosting. It is sold on demand, typically by the minute or the hour; it is elastic -- a user can have as much or as little of a service as they want at any given time; and the service is fully managed by the provider (the consumer needs nothing but a personal computer and Internet access). Significant innovations in virtualization and distributed computing, as well as improved access to high-speed Internet and a weak economy, have accelerated interest in cloud computing.

云服务通常有三个明显特征已区别于其他传统服务。按需分配，按时间分配，弹性分配——用户可以在任何时候接入并得到他们想要的服务；

同时服务应完全托管于供应商（用户除了一台电脑和网络接入外别无所需）。拜虚拟化和分布式计算的重大创新，高速网络的搭建和经济的进步所赐，加速了人们对于云计算技术的投入和兴趣。

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 cloud is a proprietary network or a data center that supplies hosted services to a limited number of people. When a service provider uses public cloud resources to create their private cloud, the result is called a virtual private cloud. Private or public, the goal of cloud computing is to provide easy, scalable access to computing resources and IT services.

云可以是私有或公有的。公有云可以为互联网上的任何人提供服务(目前，亚马逊Web服务是最大的公共云服务提供商。)私有云是一个专有网络或数据中心，只为数量有限的用户提供托管服务。使用公共云服务提供商的资源，创建的自己的私有云被称为虚拟私有云。无论是私人或公共，云计算的目标是提供方便，可扩展访问的计算资源和IT服务。

Infrastructure-as-a-Service like Amazon Web Services provides virtual server instanceAPI) to start, stop, access and configure their virtual servers and storage. In the enterprise, cloud computing allows a company to pay for only as much 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 utility computing.

lass(基础设施服务)像亚马逊Web服务提供虚拟服务的API(应用程序接口)来启动，停止，接

入和配置虚拟服务器和存储。在企业中，云计算允许公司只为所需要的功能和能力埋单(不需要为过剩的能力、功能埋单)，并尽可能快的带来更多的在线需求(合理分配资源)。这种为使用付费的模式类似人们为电力，汽油，和水付费的方式，有时也被称为效用计算。

Platform-as-a-service in the cloud is defined as a set of software and product development tools hosted on the provider's infrastructure. Developers create applications on the provider's platform over the Internet. PaaS providers may use APIs, website portals or gateway software installed on the customer's computer. https://www.wendangku.net/doc/0b14945421.html,, (an outgrowth of https://www.wendangku.net/doc/0b14945421.html,) and GoogleApps are examples of PaaS. Developers need to know that currently, there are not standards for interoperability or data portability in the cloud. Some providers will not allow software created by their customers to be moved off the provider's platform.

云中的PaaS(平台服务)被定义为一组在提供商的基础设施上被托管的软件和产品开发工具。开发人员创建的应用程序在互联网服务提供商的平台上。PaaS供应商可能会使用API(应用程序接口)，门户网站或网关软件来安装在客户的计算机上。GoogleApps是PaaS的典型例子。开发人员目前也需要知道，非标准的互操作或云中数据的可移植性问题在平台中同样存在。有部分供应商也许不会允许客户创建的软件被从供应商的平台上撤下。

In the software-as-a-service cloud model, the vendor supplies the hardware infrastructure, the software product and interacts with the user through a front-end portal. SaaS is a very broad market. Services can be anything from Web-based email to inventory control and database processing. Because the service provider hosts both the application and the data, the end user is free to use the service from anywhere.

SaaS(软件服务)的云计算模式，是由供应商提供基础硬件设施，软件产品，通过前端软件界面与用户交流。SaaS的市场前景非常广阔。服务可以是任何东西任何东形式，从基于网络的电子邮件到库存控制和数据库处理。因为服务提供商提供从应用程序到数据的全部支持，终端用户得以自由的在任何地方享受服务。