1. Computer Science
In Mori Laboratory, we research on what kind of system should be in the future and its realization, in terms of concept, architecture and technology. Our basic technology is called Autonomous Decentralized System(ADS) technology. This technology spreads over computer and network fields. ADS is based on the concept of analogizing living things, and was suggested in 1977. The living body is built of numerous cells, each growning up independently, maintaining by body metabolism, and going on living. Depending on concept of perceiving the system that it is consisted by autonomous controllability and autonomous coordinability, ADS technology achieves fault tolerance, on-line maintenance and on-line expansion of the computer system.
(1) Autonomous Decentralized Database System (ADDS)
ADDS is a distributed database system based on the concept of ADS. Usually, transactions for database systems require qualities of ACID, where C stands for consistency. Here, consistency indicates the quality for avoiding changes while committing transactions.
In ADDS, the system alleviates the strictness of consistency by allowing each database to update the data up to certain amount, without synchronizing with the other database systems. The amount that each database can freely update is named AV (Available Volume). Each database system is able to freely update the AV, and the amount changes caused by the update is used for background coordination with mobile agents for synchronization with the other database systems.
The introduction of AV enables increase in response time for distributed database system, as well as allowing heterogeneity transparency for database that adopts different policies. Like ADDS, ADS enables systems to adapt heterogeneity requests. The characteristic of satisfying heterogeneity transparency and adaptability is called assuarance.
(2) Faded Information Field (FIF)
The importance of the software technology called agent, which travels around networks to obtain information with data of its user's preference and situation instead of the user, is becoming recognized. FIF utilize such a technology to allow massive information distribution. In FIF, as a node parts from the SP (Service Provider), the node's information capacity decreases, but on the other hand, the number of nodes increase. The user of the system first launch a pull mobile agent, which climbs up the mountain of FIF, obtains reqiured information, then returns back to the user. When information provided by the SP is updated, a push mobile agent from the SP is launched, which descends the FIF mountain. As the agent descends, it reduces the size of carrying data. Thus, the upper nodes of FIF consist more information than the lower nodes.
As services provided by SPs and user's requests become more and more varied, it is necessary to construct a system that dynamically adapts to the changes in the environment. In Mori laboratory, such a system is called community architecture. In community architecture, groups of subsystems named community are created, which flexibly re-construct as the envronment changes. Also, with in the community, information, functions and resources are shared. Community architecture is studied as the information infrastructure system technology for the coming ubiquitous society.
(4) Assurance System
The assurance system is the system that is adaptable for different requirements, when connecting two individual systems that have differnet requirement levels. Each system can have its autonomy of different requirement levels, whereas the system have to achieve their individual objectives without violating mutuality and the systems assurance. For example, Real Time System and Non-Real Time System, Mission Critical System and Consumer-Oriented System, Control System and Information System, etc.