云计算相关述语
云计算相关述语
云计算相关
http://en.wikipedia.org/wiki/Cloud_computing
云计算主要有三种类型：IaaS、PaaS和SaaS，分别代表基础架构即服务、平台即服务和软件即服务
IaaS，提供 CPU，网络，存储等基础硬件的云服务。在 IaaS 这一层，著名的云计算产品有 Amazon 的 S3(Simple Storage Service)， 提供给用户云存储服务。
PaaS，提供类似于操作系统层次的服务与管理 ，比如 Google GAE，你可以把自己写 Java 应用 ( 或者是 Python) 丢在 Google 的 GAE 里运行，GAE 就像一个”云”操作系统，对你而言，不用关心你的程序在那台机器上运行。
SaaS，就是我们所熟悉的软件即服务。事实上 SaaS 的概念的出现要早于云计算，只不过云计算的出现让原来的 SaaS 找到了自己更加合理的位置。本质上，SaaS 的理念是：有别的传统的许可证付费方式 ( 比如购买 Windows Office)，SaaS 强调按需使用付费。SaaS 著名的产品很多，比如 IBM 的 LotusLive，Salesforce.com 等
IaaS, PaaS, SaaS (Explained, Compared)
SaaS: Software as a Service
Cloud application services or “Software as a Service” (SaaS) are probably the most popular form of cloud computing and are easy to use. SaaS uses the Web to deliver applications that are managed by a third-party vendor and whose interface is accessed on the clients’ side. Most SaaS applications can be run directly from a Web browser, without any downloads or installations required. SaaS eliminates the need to install and run applications on individual computers. With SaaS, it’s easy for enterprises to streamline their maintenance and support, because everything can be managed by vendors: applications, runtime, data, middleware, O/S, virtualization, servers, storage, and networking. Gmail is one famous example of an SaaS mail provider.
PaaS: Platform as a Service
The most complex of the three, cloud platform services or “Platform as a Service” (PaaS) deliver computational resources through a platform. What developers gain with PaaS is a framework they can build upon to develop or customize applications. PaaS makes the development, testing, and deployment of applications quick, simple, and cost-effective, eliminating the need to buy the underlying layers of hardware and software. One comparison between SaaS vs. PaaS has to do with what aspects must be managed by users, rather than providers: With PaaS, vendors still manage runtime, middleware, O/S, virtualization, servers, storage, and networking, but users manage applications and data.
PaaS provides the computing infrastructure, the hardware, and the platforms that are installed on top of the hardware. Similar to the way that you might create macros in Excel, PaaS allows you to create applications using software components that are controlled by a third-party vendor. PaaS is highly scalable , and users don’t have to worry about platform upgrades or having their site go down during maintenance. Users who benefit most from PaaS include companies who want to increase the effectiveness and interactivity of a large staff. For the needs of larger companies and independent software vendors, Apprenda is one provider of a private PaaS for .Net business-application development and deployment.
