The synchronization and replication is also an essential technology of mobile database . comparing trade distributed database environment , mobile computing environment has characteristics of high frequency disconnection , network condition diversity , network communications dissymmetry and so on 移动计算环境与传统的分布式计算环境相比有频繁的断接性、网络条件的多样性以及网络通信的非对称性等特点,这些特点使得传统的分布式数据库技术不能有效支持移动计算环境。
As a more flexible and complex mobile computing environment , mobile database comes into existence . nowadays how to construct a mobile database based on traditional distributed database technologies , which can adapt the wireless environment , has been a new direction to database researches the thesis particularly studies the status of mobile database , the thesis firstly discusses architectures , characteristics , some key technologies . and the thesis presents a data consistency maintenance solution based on bi - asynchronism data replication technology ( b - adr ) , which well maintains data consistency in mobile database environment 论文对移动数据库技术的发展现状进行了广泛论证,深入研究了移动计算环境下的分布式系统,移动数据库的典型系统模型,讨论了移动数据库系统体系结构、特点及其应用前景,移动数据库的关键技术,并针对数据复制创造性的提出了一种基于双向异步复制的数据一致性解决方案( b - adr ) ,较好的解决了移动数据库领域的数据一致性问题。
Since one of the goals of the scenario is to illustrate the different database environments and their impact on the application code , we will try to do a side - by - side demonstration of the two applications one using db2 native xml , and the other an open source rdbms like mysql with limited or no xml capabilities 因为该情景的一个目的是说明不同的数据库环境以及它们对应用程序代码的影响,所以我们将对两个应用程序进行同时说明,一个应用程序使用db2原生xml ,另一个应用程序使用类似mysql的开放源码rdms ,具有有限的xml功能或没有任何xml功能。
Secondly , based on reference model and data - flow model of traditional cad systems , a cooperative information model of collaborative cad systems for the aircraft cooperative design system was put forward . the information model includes various correlative data and knowledge for the plan , development , implement and realization of the aircraft project . according to the demands of the information model we setup distributed database environment for the cooperative system 通过分析传统cad系统的参考模型和数据流模型,结合协同开发环境的需要建立了协同cad设计系统的信息模型,并为从项目计划、项目开发、项目实施到完成的产品开发全过程中涉及的各种信息和知识,如人员信息、项目信息、通讯信息、设计信息等建立信息模型。