Studies on Wide-Area Distributed Coordination Mechanisms

高度发达的信息社会的基础技术已经发展起来，包括最近的网络技术。然而，它们不足以在网络上完成我们的全部工作，因此开发考虑到目的的技术是很重要的。在这种情况下，实现数据共享的数据库技术是解决各种问题的最重要的技术。数据共享使我们能够利用共享数据进行通信，在系统和用户之间进行协同工作。如果工作是某种交易，问题就会很复杂。事务是原子过程，它具有将完全执行或根本不执行的属性。时间是合作工作的重要因素。实时处理是指将在一定时间内完成的过程。如果数据是共享的，则很难预测进程何时结束，因为进程必须等待其他进程使用的数据。此外，考虑到系统的安全性，每个用户可以使用不同的数据是很重要的。这个函数称为视图函数。这些难题是与elmagarmid教授（普渡大学）的分布式事务处理，liu教授（iii - inois- university）的实时处理和rundensteiner副教授（密歇根大学）的高级视图功能合作研究的。他们对这些问题进行了讨论，并帮助我们对科研合作者进行了指导和国外科研合作者的推荐。

Base technologies for highly-developed information society have been developed including recent network technologies. However, they are not sufficient to do our whole work on the network, so that it is important to develop technologies with consideration of the purpose.In such a case, database technology which realizes data sharing is the most important technology to solve various problems.Data sharing enables us to do cooperative work among systems and users utilizing communication through shareddata. Problems will be complex if the work is some kind of transaction.Transaction is the atomic process, that has the property that it will be executed perfectly or will not be executed at all.Time is the important factor of cooperative work. Real-time processing is the process which will be finished within a certain period. It is difficult to predict when processes are finished if data are shared, because processes have to wait data which are used by other processes. Furthermore, it is important that each user can use different data because of the system security. This function is called the view function. These difficult problems are studied in cooperation with Prof.Elmagarmid (Purdue Univ.) for distributed transaction processing, Prof.Liu (IIIinois-Univ.) for real-time processing, and Associate Prof.Rundensteiner(Michigan Univ.) for advanced view functions.They have discussed these problems and helped us with the guidance for research cooperators and the recommendation of foreign research cooperators.