Together with NetworkedPlanet's Graham Moore I had the honour of delivering the opening keynote of this year's Springer published Topic Maps Research and Applications conference in Leipzig. We spoke on various aspects of distributed, cross-implementation, cross-platform topic map based registries.

Topic map engines are highly efficient tools for the structuring of and access to information - provided that it is either centrally stored or, at least, does not leave the confines of particular implementations. In practice, metadata is often stored in heterogeneous, distributed registries across the web. In order to scale topic maps to a resource oriented world, we either need to aggregate data from local sources in one registry (publish-subscribe model) or treat those sources as nodes in a virtual semantic peer-to-peer network.

We have looked at one exemplary network of registries, the nascent pan-European eGovernment Resource Network (eGRN) that even now in its prototypical stage consists of two separate nodes running on different platforms and are powered by different implementations. They exchange their data through ATOM-based feeds which carry topic map fragments as payloads, making, as a side effect, every topic a first-class citizen in an eGovernment Resource Oriented Architecture (ROA).