In this paper, we employ genetic algorithms to solve the migration problem (MP). We propose a new encoding scheme to represent trees, which is composed of two parts: the pre-ordered traversal sequence of tree vertices...In this paper, we employ genetic algorithms to solve the migration problem (MP). We propose a new encoding scheme to represent trees, which is composed of two parts: the pre-ordered traversal sequence of tree vertices and the children number sequence of corresponding tree vertices. The proposed encoding scheme has the advantages of simplicity for encoding and decoding, ease for GA operations, and better equilibrium between exploration and exploitation. It is also adaptive in that, with few restrictions on the length of code, it can be freely lengthened or shortened according to the characteristics of the problem space. Furthermore, the encoding scheme is highly applicable to the degree-constrained minimum spanning tree problem because it also contains the degree information of each node. The simulation results demonstrate the higher performance of our algorithm, with fast convergence to the optima or sub-optima on various problem sizes. Comparing with the binary string encoding of vertices, when the problem size is large, our algorithm runs remarkably faster with comparable search capability. Key words distributed information retrieval - mobile agents - migration problem - genetic algorithms CLC number TP 301. 6 Foundation item: Supported by the National Natural Science Foundation of China (90104005), the Natural Science Foundation of Hubei Province and the Hong Kong Polytechnic University under the grant G-YD63Biography: He Yan-xiang (1952-), male, Professor, research direction: distributed and parallel processing, multi-agent systems, data mining and e-business.展开更多
Mobile agents are able to migrate among machines to achieve their tasks. This feature is attractive to design, implement, and maintain distributed systems because we can implement both client-side and server-side prog...Mobile agents are able to migrate among machines to achieve their tasks. This feature is attractive to design, implement, and maintain distributed systems because we can implement both client-side and server-side programming in one mobile agent. However, it involves the increase of data traffic for mobile agent migrations. In this paper, we propose program code caching to reduce the data traffic caused by mobile agent migrations. A mobile agent consists of many program codes that define a task executed in each machine they migrate; thus, the mobile agent migration involves the transfer of their program codes. Therefore, our method reduces the number of the transfer of program codes by using program code cache. We have implemented our method on a mobile agent framework called Maglog and conducted experiments on a meeting scheduling system.展开更多
针对移动边缘计算中用户移动性导致服务器间负载分布不均,用户服务质量(Quality of Service,QoS)下降的问题,提出了一种移动性感知下的分布式任务迁移方案。首先,以优化网络中性能最差的用户QoS为目标,建立了一个长期极大极小化公平性问...针对移动边缘计算中用户移动性导致服务器间负载分布不均,用户服务质量(Quality of Service,QoS)下降的问题,提出了一种移动性感知下的分布式任务迁移方案。首先,以优化网络中性能最差的用户QoS为目标,建立了一个长期极大极小化公平性问题(Max Min Fairness,MMF),利用李雅普诺夫(Lyapunov)优化将原问题转化解耦。然后,将其建模为去中心化部分可观测马尔可夫决策过程(Decentralized Partially Observable Markov Decision Process,Dec-POMDP),提出一种基于多智能体柔性演员-评论家(Soft Actor-Critic,SAC)的分布式任务迁移算法,将奖励函数解耦为节点奖励和用户个体奖励,分别基于节点负载均衡度和用户QoS施加奖励。仿真结果表明,相比于现有任务迁移方案,所提算法能够在保证用户QoS的前提下降低任务迁移率,保证系统负载均衡。展开更多
Mobility is inherent in Internet,traditional message passing,RPC,or Remote Evaluation,can not meet more and more various mobility requirements. Mobile Agent implements computation migration,including data,code and con...Mobility is inherent in Internet,traditional message passing,RPC,or Remote Evaluation,can not meet more and more various mobility requirements. Mobile Agent implements computation migration,including data,code and control,is a good way to suit Internet. Migration mechanism is the key technology of mobile Agent. We discuss it from the perspective of both system programmer and application programmer and introduce migration mechanisms of some famous Java based mobile Agent system.At last,present the structured migration mechanism of self-designed mobile Agent system Mogent.展开更多
文摘In this paper, we employ genetic algorithms to solve the migration problem (MP). We propose a new encoding scheme to represent trees, which is composed of two parts: the pre-ordered traversal sequence of tree vertices and the children number sequence of corresponding tree vertices. The proposed encoding scheme has the advantages of simplicity for encoding and decoding, ease for GA operations, and better equilibrium between exploration and exploitation. It is also adaptive in that, with few restrictions on the length of code, it can be freely lengthened or shortened according to the characteristics of the problem space. Furthermore, the encoding scheme is highly applicable to the degree-constrained minimum spanning tree problem because it also contains the degree information of each node. The simulation results demonstrate the higher performance of our algorithm, with fast convergence to the optima or sub-optima on various problem sizes. Comparing with the binary string encoding of vertices, when the problem size is large, our algorithm runs remarkably faster with comparable search capability. Key words distributed information retrieval - mobile agents - migration problem - genetic algorithms CLC number TP 301. 6 Foundation item: Supported by the National Natural Science Foundation of China (90104005), the Natural Science Foundation of Hubei Province and the Hong Kong Polytechnic University under the grant G-YD63Biography: He Yan-xiang (1952-), male, Professor, research direction: distributed and parallel processing, multi-agent systems, data mining and e-business.
文摘Mobile agents are able to migrate among machines to achieve their tasks. This feature is attractive to design, implement, and maintain distributed systems because we can implement both client-side and server-side programming in one mobile agent. However, it involves the increase of data traffic for mobile agent migrations. In this paper, we propose program code caching to reduce the data traffic caused by mobile agent migrations. A mobile agent consists of many program codes that define a task executed in each machine they migrate; thus, the mobile agent migration involves the transfer of their program codes. Therefore, our method reduces the number of the transfer of program codes by using program code cache. We have implemented our method on a mobile agent framework called Maglog and conducted experiments on a meeting scheduling system.
文摘Mobility is inherent in Internet,traditional message passing,RPC,or Remote Evaluation,can not meet more and more various mobility requirements. Mobile Agent implements computation migration,including data,code and control,is a good way to suit Internet. Migration mechanism is the key technology of mobile Agent. We discuss it from the perspective of both system programmer and application programmer and introduce migration mechanisms of some famous Java based mobile Agent system.At last,present the structured migration mechanism of self-designed mobile Agent system Mogent.
