For an example of finding objects by external link, see JAXRSearchByExternalLink.java in the directory<INSTALL>/registry/samples/search-external-link/src, which searches for objects that have a specified external link. The http.proxyHost and http.proxyPort properties are specified in the run target in the build.xml file.
To obtain results from this example, first run the publish-object example described in Adding Classifications: Example.