| 摘要: |
| 面向对象数据库的许多应用环境需要频繁的模式演以化,但模式演化以后,基于先前模式的应用程序因此而不得不修改或重编,这就造成了巨大的软件浪费.提出了基于路径无关语言的等价模式演化方案来解决这个问题.首先,路径无关语言是一种面向对象数据库的编程语言,它能使程序脱离对细节数据模式的导航,对模式演化具有较强的适应性.而等价模式演化是一种新的模式演化方案,它能保证用路径无关语言编写的应用程序在模式演化以后无须修改而完全重用.此外,在实现等价模式演化的系统中,为了减少演化开销以及不增加用户的额外编程负担,提出了虚拟关系机制和对象演化技术. |
| 关键词: 可适应性软件的设计与发展 模式演化 面向对象数据库 软件重用 虚拟关系 |
| DOI： |
| 分类号: |
| 基金项目:国家863高科技发展计划资助项目(863-306-ZD02-02-9) |
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| An Equivalent Schema Evolution Policy Based on Path-Independence Language |
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DONG Chuan liang,LU Jia heng,YANG Hong,DONG Wen wei
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| Abstract: |
| The schema in object-oriented database (OODB) often experiences considerable changes during the development for typical application areas. After the update, the existing application programs based on the formerly schema have to be modified or rewritten, which makes a great deal of application programs obsolete. This paper addresses the problem by providing equivalent schema evolution (ESE) mechanism based on path independence (PI) program. Path-Independence program is employed as OODB's specification formalism for enhancing the adaptability of database program against the schema evolution. Equivalent schema evolution can make the existing path-independence language reuse without any modification after the schema has been updated. In addition, a solution approach of remaining the equivalent schema evolution mechanism is described in this paper as a effective working system, which as its essential feature the system to support virtual relation mechanism and object-evolving technology. |
| Key words: adaptive software specification and development schema evolution object -oriented database software reuse virtual relation |
