What is IaaS, PaaS, SaaS?
Look at the following icon:
We can understand this as:
Iaas:infrastructure-as-a-service (infrastructure as service)
Paas:platform-as-a-service (Platform as service)
Saas:software-as-a-service (software as a service)
The first layer is called IaaS, sometimes called Hardware-as-a-service, and a few years ago if you wanted to run some enterprise apps on your office or company web site, you needed to buy a server, or other expensive hardware to control your local apps and get your business running.
But now there are IaaS, you can outsource the hardware to other places. IaaS Company will provide OTC servers, storage and network hardware that you can rent. Save on maintenance costs and office space, companies can use these hardware at any time to run their applications.
Some of the big IaaS companies include Amazon, Microsoft, VMWare, Rackspace and Red Hat. However, these companies have their own expertise, such as Amazon and Microsoft to provide you with not only IaaS, they will be able to rent their computing capacity to host your site.
The second layer is called PAAs, sometimes called middleware. All of your company's development can be done at this level, saving time and resources.
PAAs provides solutions for various development and distribution applications, such as virtual servers and operating systems, on the web. This saves you the cost of your hardware and makes it easier to work together in a decentralized studio. Web application management, application design, application virtual hosting, storage, security, and application development collaboration tools.
Some large PAAs providers have Google App engine,microsoft azure,force.com,heroku,engine yard. The recently rising companies have Appfog, Mendix and Standing Cloud
The third tier is called SaaS. This layer is a daily contact with your life layer, mostly through web browsers to access. Any application on a remote server can be run over the network, which is SaaS.
The services you consume are fully accessible from Web sites such as Netflix, MOG, Google Apps, Box.net, Dropbox, or Apple's icloud. While these Web services are used for business and entertainment or both, this is part of the cloud technology.
Some of the SaaS applications used for business include Citrix's Gotomeeting,cisco Webex,salesforce Crm,adp,workday and SuccessFactors.