- Xquery is based on knowing the structure of the data being searched. It doesn't work well for general-purpose searches.
- SDLIP is complex, doesn't have a query language
- DASL is linked to SQL, but pretty good
- Z39.50 is complex and fragile
OCLC's SRW server
Ralph LeVan at OCLC maintains a Java-based SRW/SRU server package. Out of the box, it can connect to OCLC's Pears database and the Lucene indexes created by DSpace.
SRWServletInfo reads the config files and sets up properities for all "known" databases.