An architectural style defines as a family of such systems in terms of a (1) of structural organization. More specifically, an architectural style defines a vocabulary of (2) and connector types, and a set of (3) on how they can be combined. For many styles there may also exist one or more (4) that specify how to determine a system's overall properties from the properties of its parts. Many of architectural styles have been developed over the years. The best-known examples of (5) architectures are programs written in the Unix shell.
空白（2）处应选择（）
A.metadata
B.components
C.models
D.entities
参考答案：B
解析：一种架构风格以一种结构化组织模式定义一组这样的系统。具体来说，一种架构风格定义了一个构件及连接器类型的词汇表，以及一组关于它们如何能够被关联的约束。对于许多风格来说，可能也存在一个或多个语义模型，从系统部件的特性来确定系统的整体特性。许多架构风格已经发展了很多年，众所周知的管道一过滤器架构的例子就是用UNIXshell编写的程序。