题目详情

本题作答（_问题1_）： System quality attributes have been of interest to the software community at least since the 1970s. There are a variety of published taxonomies and definitions, and many of them have their own research and practitioner communities. From an （ 问题1） perspective, there are three problems with previous discussions of system quality attributes: The definitions provided for an attribute are not operational. It is （ 问题2） to say that a system will be modifiable. Every system is modifiable with respect to one set of changes and not modifiable with respect to another. The other attributes are similar. A focus of discussion is often on which quality a particular aspect belongs to. Is a system failure an aspect of availability, an aspect of security, or an aspect of usability? All three attribute communities would claim ownership of a system failure. Each attribute community has developed its own （ 问题3）. The （ 问题4）community has "events" arriving at a system, the security community has "attacks" arriving at a system, the availability community has "failures" of a system, and the usability community has "user input." All of these may actually refer to the same occurrence, but are described using different terms. A solution to the first two of these problems (nonoperational definitions and overlapping attribute concerns) is to use quality attribute（ 问题5）as a means of characterizing quality attributes. A solution to the third problem is to provide a brief discussion of each attribute-concentrating on its underlying concerns-to illustrate the concepts that are fundamental to that attribute community.