Introduction and summary of cloud computing

Proposal of cloud computing

Data availability and integrity are fundamental to the use of cloud services. Cloud computing has developed rapidly in various application fields in recent years due to the characteristics of on-demand services, resource pool sharing, and charging by service. The development history of computers has gone through host systems and centralized computing, utility computing, personal computer and desktop computing, distributed computing, grid computing, and software as a service (SAAS ), the emergence of cloud computing and other stages. Judging from the evolution of the computing model, it is characterized by centralization, decentralization, and centralization. Today, computing models are showing a concentrated trend. Figure 2-1 shows the development of a computing model.

 

Cloud computing is a new computing model. Its main advantage is to respond to users' computing resources in real time, that is, to supply or recycle corresponding resources according to users' needs. You can apply for only a portion of resources when the application starts to run. When you need more resources, you can apply for more computing resources from the cloud service provider as needed. The formation of cloud computing corresponds to a combination of multiple technologies. This combination makes it a very simple concept of service a reality.

Cloud computing definition, characteristics and classification

There are different definitions of cloud computing. In January 2011, NIST (National Institute of Standards and Technology) published the following definition of cloud computing: cloud computing is a usage model for IT resources, it provides ubiquitous, convenient, and on-demand network access to shared computing resources (such as networks, servers, storage, applications, and services.

With the development of cloud computing, in order to have a judgment standard for cloud computing, the nine major features of cloud computing are summarized as follows:

(1) It capabilities are provided as services
(2) Network Access
(3) User self-service
(4) Provide open service access and management interfaces
(5) continuous service updates and incubation

(6) aggregate resources into a pool
(7) automated management and fast delivery
(8) elastic Scaling
(9) resource usage Measurement

Based on the deployment method and scope of the cloud computing service, the cloud can be divided into three categories: public cloud, private cloud and hybrid cloud. In the public cloud, users can lease Resources in the cloud, or lease infrastructure to provide services to other users, in order to ensure the security of communication and data sharing among users. Design a secure access control mechanism between cloud computing users [HL [81. Based on the cloud computing service type, the cloud can be divided into three layers: software as a service SaaS (software as a service SAAS), platform as a service (PAAs. infrastructure as a service (IAAS ). Generally, computing environments have software, operating system, and hardware layers. The three service models provided by cloud computing correspond to three levels of the general computing environment. These three service models are software as a service (SAAS), platform as a service (PAAs), and infrastructure as a service (IAAS ).

(I) SAAS is cloud application software, which encapsulates the application software and provides it to users. End users can use browsers to obtain required or customized cloud application services over the network.

(2) Paas is an important layer between infrastructure and applications. Paas integrates infrastructure resources to provide users with application development environments and deployment platforms, facilitates the interaction between applications and infrastructure.

(3) IAAs encapsulates infrastructure resources such as hardware devices into services for users to use. You can run any software on the infrastructure, and the service provider is only responsible for managing the infrastructure.

The relationship between the three is shown in 2-3.

 

Introduction and summary of cloud computing