对象标识的语义及构成

Semantics and Implementation of Object Identity

1.引言在面向对象模型中,对象标识是一个重要概念,文[3,9]均将其做为O-O模型的必备特征。在NF^2关系模型中,也有人引入了对象标识(元组标识和关系标识)。现在人们之所以重视对象标识,是因为在描述嵌套结构的复杂事物、处理数据共享、描述历史数据和版本特征等方面,对象标识具有重要作用。文[10]强调了由系统管理、独立于内容、独立于结构、独立于地址的强标识;文[15]指出了对对象标识的错误理解。

Based on the three database schema in ANSI/X3/SPARC, the full object identity, including, objective object identity, conceptual object identity, internal object identity, is introduced. The objective object identity is a special primary key, the internal object identity corresponds to the object identity oid in usual object-oriented systems. The object equality based on the full object identity is also discussed. The fall object identity can be used not only to identify the objects in user interface, but also to manage the objects in computer systems, makes object identity further perfect. And it is also available in combining object-oriented model with value-oriented model.