Load balancing issues in super-peer-based publish/subscribe digital libraries

The authors presented a hyper-graph partitioning based approach to the problem of load-balancing in large-scale P2P-based digital libraries. In such libraries, in addition to publishing digital content, peer-clients may subscribe their intent to be notified whenever digital content matching appropriate meta-data keywords is published in the library (a.k.a. continuous queries or selective dissemination of information), as well as perform more traditional point queries. The digital content, as well as the continuous queries, are partitioned among a number of blocks, and each super-peer server in the network is responsible for handling only one of these partitioned blocks. Preliminary results showing that the hyper-graph partitioning approach scales well with the number of published documents or continuous queries, and with the size of the network were presented. The results show that partitioning-based load balancing of the super-peers leads to significant improvements of the average response time for point or continuous queries, and much reduced storage requirements of the library metadata.