We have designed a scalable and expressive naming system called SENS, capable of retrieving information of computing and content resources distributed widely across the Internet through exact queries and multi-attribute range queries over resource names. Our system utilizes a descriptive naming scheme to name resources and a multi-dimensional resource ID space for message routing through an overlay network of name servers (NSs). The resource ID space is constructed on the overlay network based on CAN routing algorithm. Our novel mapping scheme between resource names and resource IDs preserves resource ID locality while still achieving good load balancing regarding resource information distribution. We also propose a multicast routing algorithm to deliver resource information and a broadcast routing algorithm to route query messages to corresponding NSs with small cost of message transmission. Our simulation results show that our system can achieve good routing performance and load balancing.

At present, vast numbers of information resources are available on the Internet. However, one emerging issue is how to search and exploit these information resources in an efficient and flexible manner with high scalability. In this study, we focused our attention on the design of a distributed hash table (DHT)-based search system that supports efficient scalable multi-attribute queries of information resources in a distributed manner. Our proposed system, named D-AVTree, is built on top of a ring-based DHT, which partitions a one-dimensional key space across nodes in the system. It utilizes a descriptive naming scheme, which names each resource using an attribute-value (AV) tree, and the resource names are mapped to d-bit keys in order to distribute the resource information to responsible nodes based on a DHT routing algorithm. Our mapping scheme maps each AV branch of a resource name to a d-bit key where AV branches that share a subsequence of AV pairs are mapped to a continuous portion of the key space. Therefore, our mapping scheme ensures that the number of resources distributed to a node is small and it facilitates efficient multi-attribute queries by querying only a small number of nodes. Further, the scheme has good compatibility with key-based load balancing algorithms for DHT-based networks. Our system can achieve both efficiency and a good degree of load balancing even when the distribution of AV pairs in the resource names is skewed. Our simulation results demonstrated the efficiency of our solution in terms of the distribution cost, query hit ratio, and the degree of load balancing compared with conventional approaches.

With the proliferation of various types of computing and networking resources in ubiquitous computing environments, an architecture allowing mobile users to flexibly access these resources is desirable. We have focused our attention on the access link resources of devices surrounding users. Our framework named Personal Mesh allows personal devices to seamlessly access the Internet via appropriate access links available in a personal area network. The Personal Mesh deals with two technical issues: access link selection management and a PAN mobility support mechanism. In this paper, we describe the design and implementation of Personal Mesh and show the effectiveness of our system by experiment.