Since it appears that development of the resolver code is stagnant due to response from my previous message containing patches, I'm not sure if it still worth the effort to submit others.
However, for a project I'm working on, I've made a couple of other modifications that may be of interest to others: (1) Bug-fix to honor xml.catalog.verbosity system property. I noticed that if one does not use CatalogManager.properties, this system property is never checked. (2) Proper setting of systemID of InputSource of SAX parsing when parsing XML catalog files. W/o this fix, if a catalog file has references to external entities using relative SYSTEM identifiers, they are resolved relative to the current working directory versus the location of the catalog file being parsed. In my case, I was dealing with catalog files that included <!DOCTYPE catalog SYSTEM "..."> declarations using relative paths to catalog.dtd. Things would bomb out during parsing since the SAX parser could not find the file specified due to invalid base URI context. If there is interest, I can post patches. --ewh