Thank you, Jeroen, for pointing to the discussion around metadata discovery and harvesting.
As you know, the discussion at the OSGeo geodata discovery group is still alive: https://geodata.osgeo.org/servlets/BrowseList?listName=geodata ; see also some notes from a FOSS4G meeting http://tinyurl.com/kajzk.
The comparison you mentioned can be found here together with a list of open source libraries, validation tools etc. http://www.gis.hsr.ch/wiki/OAI-PMH . Please note that OAI-PMH is a lightweight harvesting protocol which sits on top of catalogs. OGSs CSW (or WFS profiles) to me serve different purposes, doing distributed queries (if looking for alternatives to CSW look at SRU/SRW and OpenSearch protocols which are lightweight implementations of Z39.50!). With OAI-PMH no filter and no ISO 19115/9/ebRIM/profile implementations is required for (meta) data providers. Indexing, filtering and other innovative functions is done at the other part of the protocol partners inside search services like GeoNetwork.
The most important thing now is to find a common model for metadata exchange as indicated here http://tinyurl.com/kfkyv .
Any comments are welcome! Hopefully we can freeze this model by end of September and release OAI-PMH implementations by December. I will implement it in my tools (see http://www.gis.hsr.ch/gmdb/oai_pmh_data_provider/) and I’m aware of about two or three other Open Source projects which consider adopting it.
– Stefan