Three cloud computing service models: IaaS, PaaS and SaaS
"Cloud" is actually a metaphor for the Internet, the "cloud computing" is actually use the internet to access applications running on remote storage or server, data, or services.
Any use Internet-based computing, storage and development company, can be called technically in a cloud of company. However, not all companies are the same cloud.
Summary: the cloud is stratified
Any offer their services on the Internet companies can be called cloud computing company. In fact, cloud computing sub-layers, namely, Infrastructure (infrastructure) -as-a-Service, Platform (platform) -as-a-Service, Software (Software) -as-a-Service. Infrastructure At the bottom, in the middle of the platform, the software at the top. Some other "soft" layer on top of these layers can be added.
Share almost on a known good example :( https://www.zhihu.com/question/20387284/answer/28514161 )
If you are a webmaster, you want to build a website. Do not use cloud services, inputs you need about: buy a server, install the server software, write web application.
Now you follow the trend, with the popular cloud computing:
- If you are using IaaS services, it means you do not have to buy their own servers, and virtual machines Which just buy, but still needs its own server software installed
- If you are using PaaS services, it means that you either need to buy a server, the server does not need to install their own software, only need to develop their own program website
- If you go further, buy some online forums and online store services, which means you do not have to develop their own website program, only you need to use them to develop a good program, and they will be responsible for upgrades, maintenance, such as adding servers and you only need to concentrate on operations, that is, for SaaS .
A, IaaS: Infrastructure-AS-A-Service (Infrastructure as a Service)
The first layer is called IaaS, sometimes called Hardware-as-a-Service, a few years ago if you wanted to run some business applications in the office or on the company's Web site, you need to buy a server, or other expensive hardware to control local application, to make your business up and running.
But now there's IaaS, you can outsource the hardware to go anywhere else. IaaS company will provide off-site servers, storage and networking hardware, you can rent. Saves maintenance costs and office space, the company can take advantage of these hardware at any time to run their applications.
IaaS some large companies, including Amazon, Microsoft, VMWare, Rackspace and Red Hat. But these companies in turn have their own expertise, not only IaaS such as Amazon and Microsoft to provide you with, they will be rented to you to computing power host your site.
Two, PaaS: Platform-as-a-Service (Platform as a Service)
The second layer is called PaaS, sometimes also known as middleware. You all development can be carried out at this level, saving time and resources.
PaaS company offers a variety of online solutions for developing and distributing applications, such as virtual servers and operating systems. This saves you the cost of the hardware, but also to cooperation between the dispersed studio easier. Web application management, application design, application hosting, storage, security, collaboration and application development tools.
Some large PaaS providers have Google App Engine , in the Microsoft Azure, the Force.com, Heroku, Engine Yard . The recent rise of the company AppFog , Mendix and Standing Cloud
Three, SaaS: Software-as-a-Service (software as a service)
The third layer is the so-called SaaS. This layer is a layer in contact with your life every day, mostly to access via a web browser. Any application on a remote server can be run over the network, is a SaaS.
Your consumer services such as Netflix entirely from the web, MOG, Google Apps, Box.net, Dropbox or Apple's iCloud there into these categories. Although these web services are used for business and pleasure or both, but it can be considered part of cloud technology.
Some used as SaaS business applications including Citrix's GoToMeeting, Cisco's WebEx, Salesforce's CRM, ADP, Workday and SuccessFactors.
Comparison between the four, Iaas and Paas
The main role of PaaS is a development and runtime platform as a service to users, and the main role is to provide IaaS virtual machines or other resources as a service to users. Next, compare the PaaS and IaaS in seven areas:
1) development environment: PaaS basic will provide developers with a complete range of development and test environments, including the IDE, and IaaS or follow the main aspects of the user before the more familiar set of development environment, but because before the set and development environment in the cloud integration is quite lacking, so is not very convenient to use.
2) Supported applications: mainly because IaaS provides virtual machines, virtual machines and general support for multiple operating systems, so the support IaaS range of applications is very broad. But if you want an application can run in a PaaS platform is not an easy task, because not only need to ensure that this application is based on the language of the platform supported, but also to ensure that the application can only call this platform supported by the API If the application calls the platform does not support the API, you will need to be modified for this application.
3) open standards: Although many IaaS platform there are some private function, but because of OVF and other agreements, making cross-platform IaaS and avoid vendor lock-in which both sides are steadily moving forward. The situation PaaS platform is not optimistic, because both Google's App Engine, Force.com or Salesforce, there are some private API.
4) Scalability: PaaS platform will automatically adjust resources to help run their applications on to better deal with unexpected traffic. The IaaS platform developers will need to manually adjust the resources to cope.
5) consolidation ratios and economy: PaaS platform integration rate is very high, such as representatives of Google App Engine PaaS can carry thousands of applications on a single server, while the consolidation of common IaaS platform will not exceed 100, and generally around 10, so that the economy is not as IaaS PaaS.
6) Accounting and Regulatory: Because PaaS platform in both billing and supervision not only reached the IaaS platform can match the operating system level, for example, CPU and memory usage, etc., but also to achieve the application level, such as reaction time applications (response time) or application consumes how many affairs, etc., which will improve the accuracy of billing and management.
7) the learning curve: it is more close to the top IaaS development and management of applications and existing, rather PaaS above development is likely to need to learn a new language or a new framework, IaaS lower the learning curve.
|
|
Close |
IaaS |
| Development environment |
perfect |
ordinary |
| Supported applications |
limited |
wide |
| CURRENCY |
Short of |
Slightly better |
| Scalability |
Automatic retractable |
Manual telescopic |
| Consolidation rate and economy |
High consolidation ratios and more economical |
Low rate consolidation |
| Accounting and regulatory |
fine |
simple |
| Learning curve |
Slightly difficult |
low |
Fifth, the future of PK
In today's cloud computing environment which, IaaS is very mainstream, both Linode or Amazon EC2 or Joyent, have a place, but with the introduction of Google's App Engine, Salesforce's Force.com or PaaS such as Microsoft's Windows Azure Platform so that PaaS began to emerge. On the future of both, especially the competitive relationship between the two, I think, in the short term, because IaaS model advantages in support of the application and the learning curve in these two areas, in the short term it will make IaaS will become the first choice in the developer, but in the long run, because of the high rate of integration PaaS model enables brought economic challenges can be resolved if the PaaS such as versatility and support the application, it will be the development of alternative IaaS those "favorite" .