一种基于Java应用构件动态重定位模型

提高分布应用性能和各种资源利用率的关键途径是尽可能地减少处理机间的通信量和让处理机忙于有用的工作．在因特网环境下，现有提高分布应用性能和各种资源利用率的工作存在一定的不足，如不能在邻居局域网范围内进行负载平衡．提出了基于局域网簇和“通讯录”的应用构件动态重定位模型．在该模型中，一方面对局域网簇内负载进行平衡，另一方面针对构件远程调用决策重新定位构件或复制构件副本以提高分布应用的性能．另外，构件动态重定位模型必须满足构件迁移前后一致性，给出了一种基于通讯录的构件通信算法，解决了该一致性问题并且具有较高的效率．实验结果表明该模型是可行和有效的．

Dynamic Relocation Model and Algorithm for Application Components Based on Java

The distributed application based on the Internet has been paid more and more attention to in recent years. As a global infrastructure of information storing, communicating and processing, the Internet boasts of network resources beyond measure and equips us with the capability of powerful and flexible network computing. However, it has also brought about several challenges. In technology, some problems arise such as how to reduce the network overload, to provide a flexible and adaptable distributed computing paradigm and so on. As to applications, there are problems such as active and interactive information distribution, parallel processing, load balancing and application performance. The key ways to improve distributed application performance and efficient use of all kinds of resources are minimizing the amount of inter-processor communication and making processors busy doing useful work. There still remains some deficiency in the existing work for improving distributed application performance and efficient use of all kinds of resources in the Internet. A dynamic relocation model for application component based on LAN-Cluster, whose network distance between two neighboring LANs is below a given threshold, and the address-book is proposed in this paper. In the model, on one hand, load balancing among LAN-Cluster instead of individual LAN can be carried out, extending the scope of load balancing, on the other hand, migration and replication decision of remote application components can be made by itself as an alternative to application programs or programmers by means of the address-book mechanism, better solving the problem about conflict between reduction of communication and distribution of computing load among distributed sites. In this way, higher distributed application performance can be achieved. In addition, component migration consistency is another important problem to be solved because of application component migration at run time in large-scale distributed application based on the Internet. But no existing research work provides an effective solution to the problem. This paper proposes an efficient algorithm for component communication. In this algorithm, address-book, "Home site" and direct communication mechanisms are used to guarantee component migration consistency and achieve higher communication efficiency. Our experimental results show that the model for dynamic relocation of component is feasible and efficient.