"Large Web site Technology architecture"--seventh chapter: Extensible Architecture for Web sites

Extensibility: The ability of system functions to be continuously expanded and enhanced in the case of minimal impact to existing systems. Performance in system infrastructure stability does not require frequent changes, less reliance and coupling between applications, and an agile response to demand changes. It is a system architecture design level of open and close principle, architecture design to consider the future function expansion, when the system adds new features, there is no need to modify the existing system architecture and code.

Scalability: Refers to the system can increase and decrease the resources of the way to increase (reduce) their own computing ability to deal with things, in the site often refers to the use of cluster method to increase the number of servers, improve the overall system of the throughput capacity of things.

"Large Web site Technology architecture"--seventh chapter: Extensible Architecture for Web sites