Interpretation of cloud computing and three models

Cloud computing SPI diagram

PAAs and IaaS are derived from the SaaS concept. PAAs and IaaS can provide services directly through Soa/webservices to platform users, or as a support platform for SaaS mode, indirectly to end users.
　　
1.SaaS: Services provided to customers are applications that operators run on cloud computing infrastructures, and users can access them on a variety of devices, such as browsers, through thin client interfaces. Consumers do not need to manage or control any cloud infrastructure, including networks, servers, operating systems, storage, and so on;
　　
2.PaaS: The service provided to consumers is to use the development language and tools provided by the customer (e.g. Java,python. NET, etc.) developed or acquired by the application deployed to the vendor's cloud infrastructure. Customers do not need to manage or control the underlying cloud infrastructure, including networks, servers, operating systems, storage, and so on, but customers can control which applications are deployed, or they may control the configuration of the managed environment where the application is running;
　　
3.IaaS: The service provided to consumers is the use of all facilities, including processing, storage, network and other basic computing resources, users can deploy and run arbitrary software, including operating systems and applications. Consumers do not manage or control any cloud computing infrastructure, but they can control the choice of operating systems, storage space, deployment applications, and the control of restricted network components such as firewalls, load balancers, etc.