I don't work for websolr, but I do quite a bit of work with Apache Solr. I'd imagine Java integration is supported through the native Java client, http://wiki.apache.org/solr/Solrj, which is maintained by the Solr team. There are also a number of Solr client libraries for Python, Ruby, PHP, etc. All searches against a Solr index take place over HTTP through an RPC interface, so building an API for a specific language relatively straightforward.