Three service modes for cloud computing: Iaas,paas and SaaS
Infrastructure (infrastructure)-as-a-service,platform (platform)-as-a-service,software (software)-as-a-service. Infrastructure at the bottom, platform in the middle, software at the top.
Iaas:infrastructure-as-a-service (infrastructure as a service) is the first tier.
The second layer of Paas:platform-as-a-service (Platform-service) is called PAAs, sometimes called middleware.
Saas:software-as-a-service (software as a service) is the third tier.
At the bottom of the hierarchy, the infrastructure is the service--iaas
IaaS uses virtualization technology to package computing platforms such as servers with storage and network resources, and provides them to users through API interfaces. Users do not have to rent the computer room, do not maintain their own servers and switches, only need to purchase IaaS services to be able to access these resources.
Above IaaS, platform is service--paas
PaaS built on IaaS, in addition to the infrastructure also provides the operating environment of business software, personal sites often used by the "virtual host" is actually a PaaS category, personal webmaster only to the site source code uploaded to the "virtual host" address, "virtual host" will automatically run these code generation corresponding Web page. In addition to creating the environment in which the software itself runs, PaaS usually has the appropriate storage interface, which can be invoked directly via FTP, and the user does not need to initialize the raw disk from scratch.
At the top, software is the service--saas
SaaS is the most mature and well-known type of cloud computing service, and software as a service itself is a very popular concept before cloud computing really gets hotter. The goal of SaaS is to put all business-running background environments into the cloud, providing services directly to end users through a thin client-typically a Web browser. End users request services to the cloud on demand, without maintaining any infrastructure or software running environment locally. SaaS differs from PaaS in that it is not the developer of the software that uses SaaS, but the end user of the software.