云计算历史

infrastructure. Green-screen terminals, in vogue back then, eventually evolved into personal computers. Networks went from a centralized, hierarchical design to a decentralized design. Decentralization moved the processing closer to the user meaning applications moved from thin client (processing on the server) to thick client (processing on the user/client side). Green screens were tightly coupled interfaces to the data-laden backend. Decentralization enabled developers to track process steps and state information on the server side while allowing client-side computers to do much more of the processing. The period was the birth of client-server architectures, which are central to today's modern technology-driven business. With much of the processing moving closer to the actual user, the connectivity of the user became the main limitation. Lack of connectivity led to the second age of computing. The 80s heralded the rise of the internet. Better connectivity between distributed computing systems quickly led to the development and near ubiquity of easy-to-use, visually attractive computing devices. Businesses moved quickly in exploiting this new Internet Protocol (IP)- based connectivity as local area networks expanded to globally inter-connected wide area networks. Users, however, became frustrated with poor application performance, network latency, and application timeouts. Developers were again forced to place more compute load closer to the user. Tightly coupled centralized applications did not have the functions, flexibility, or the responsiveness of a well-designed well-built decentralized application. Additionally, the late 80s gave way to a major shakeup in the telecommunications industry. The then monopolized local exchanges were mandated to separate into independent competing companies. The competition forced faster innovation, lower costs, and higher levels of reliability and service.

The following diagram depicts the various cloud computing phases: