Efficient and effective routing of content-based queries is an
emerging problem in peer-to-peer networks, and can be seen as an
extension of the traditional ``resource selection'' problem.
Although some approaches have been proposed, finding the best
architecture (defined by the network topology, the underlying
selection method, and its integration into peer-to-peer networks) is
still an open problem. In this talk, we regard different building
blocks of such architectures, among them the decision-theoretic
framework, CORI, hierarchical networks, distributed hash tables and
HyperCubes. The evaluation on a large test-bed shows that the
decision-theoretic framework can be applied effectively and
cost-efficiently onto peer-to-peer networks.