Filters for XML-based Service Discovery in Pervasive Computing

Pervasive computing refers to an emerging trend towards numerous casually accessible devices connected to an increasingly ubiquitous network infrastructure. An important challenge in this context is discovering the appropriate data and services. In this paper, we assume that services and data are described using hierarchically structured metadata. There is no centralized index for the services; instead, appropriately distributed filters are used to route queries to the appropriate nodes. We propose two new types of filter that extend Bloom filters for hierarchical documents. Two alternative ways are considered for building overlay networks of nodes: one based on network proximity and one based on content similarity. Content similarity is derived from the similarity among filters. Our experimental results show that networks based on content similarity outperform those formed based on network proximity for finding all matching documents.