Basic concepts of cloud computing

What is cloud computing

There are many ways to define cloud computing. At least 100 explanations can be found for what is cloud computing. Cloud computing is an increase, use, and delivery model of Internet-based services, often involving the provision of dynamically scalable and often virtualized resources over the Internet. The cloud is a metaphor for the internet and the Web. As a result, cloud computing can even allow you to experience the computing power of 10 trillion times per second, with such powerful computational power to simulate nuclear explosions, predict climate change and market trends. Users through the computer, notebook, mobile phone and other ways to access the data center, according to their own needs to operate.

At this stage, it is widely accepted that the National Institute of Standards and Technology defines: cloud computing is a pay-per-use model that provides available, convenient, on-demand network access and access to a configurable pool of computing resources (resources including networks, servers, storage, applications, services) that can be quickly delivered , with little or no management effort, or minimal interaction with service providers.

Liu Peng, a Chinese grid computing and cloud computing expert, gives the following definition: "Cloud computing distributes computing tasks across a vast pool of computer-based resources, enabling applications to gain compute power, storage space, and various software services as needed."

The narrow sense of cloud computing refers to the manufacturers of distributed computing and virtualization technology to build data centers or supercomputers, free or on-demand leasing to technology developers or enterprise customers to provide data storage, analysis and scientific computing services. Cloud computing in broad sense refers to the various types of services that vendors provide online software services, hardware leasing, data storage, calculation and analysis to different types of customers by establishing a cluster of network servers.

The popular understanding is that cloud computing "cloud" is the resources that exist on the server cluster on the Internet, which includes hardware resources (server, storage, CPU, etc.) and software resources (such as application software, integrated development environment, etc.), the local computer only need to send a demand information over the Internet, Thousands of computers at the far end will provide you with the resources you need and return the results to your local computer, so that the local computer has little to do, and all the processing is done in the computer cluster provided by the cloud computing provider.

Principles of cloud Computing

by distributing the calculations on a large number of distributed computers, rather than on the local computer or the remote server, the Enterprise data center will run more like the Internet. This enables enterprises to switch resources to the required applications and access the computers and storage systems as needed.

Three service models for cloud computing

Three service models for cloud computing,--iaas, PaaS, and SaaS, are recognized by the public.

(1), IaaS
IaaS (infrastructure-as-a-Service): Infrastructure as a service. Consumers can access services from a sophisticated computer infrastructure through the Internet.

(2), PaaS
PaaS (platform-as-a-Service): Platform as a service. PAAs actually refers to the software development platform as a service, in the SaaS mode to submit to the user. Therefore, PAAs is also an application of the SaaS model. However, the advent of PAAs can accelerate the development of SaaS, especially to speed up the development of SaaS applications.

(3), SaaS

SaaS (software-as-a-service): Software as a service. It is a mode of providing software over the Internet, and users do not need to purchase software, but instead rent web-based software to the provider to manage business activities. SaaS solutions have obvious advantages over traditional software, including lower upfront costs, ease of maintenance, rapid deployment, and more.

The core technology of cloud computing

Cloud Computing systems use a number of technologies, including programming models, data management technology, data storage technology, virtualization technology, cloud computing platform management technology is the most critical.

(1) Programming model
MapReduce is a Java, Python, C + + programming model developed by Google, a simplified distributed programming model and an efficient task scheduling model for parallel operations with large datasets (larger than 1TB). A rigorous programming model makes programming in a cloud computing environment simple.

(2) Mass data distribution storage technology

Cloud computing system consists of a large number of servers, while serving a large number of users, so the cloud computing system uses distributed storage to store data, with redundant storage to ensure the reliability of the data. The widely used data storage system in cloud computing systems is open source implementation HDFs for GFS developed by Google's GFS and Hadoop team.

(3) massive data management technology

Cloud computing requires the processing and analysis of distributed, massive amounts of data, so data management technologies must be able to manage large amounts of data efficiently. The data management technology in cloud computing system is mainly the BigTable data management technology of Google and the open source data management module HBase developed by the Hadoop team.

(4) Virtualization Technology
Virtualization technology enables software applications to be isolated from the underlying hardware, including splitting patterns that divide individual resources into multiple virtual resources, and aggregation patterns that combine multiple resources into a single virtual resource. Virtualization technology can be divided into storage virtualization, computational virtualization, network virtualization, and so on, which are classified into system-level virtualization, application-level virtualization, and desktop virtualization.

(5) Cloud computing platform management technology

The huge scale of cloud computing resources, the large number of servers and distribution in different locations, while running hundreds of applications, how to effectively manage these servers, to ensure uninterrupted service of the entire system is a great challenge. The platform management technology of cloud computing system can make a large number of servers work together, facilitate business deployment and opening, quickly discover and recover system failures, and realize the reliable operation of large-scale systems by means of automation and intelligence.

Basic concepts of cloud computing