Where can I find some documentation of Solrj? Does it have a wiki page or something?
It does not yet have good external documentation. We will definatly have something before solr 1.3, but for now, looking at the source and test is the best option.
Am I using this method improperly or is there a problem with the ping?
I just looked into this... you are using it correctly, there is an error in the code. Solrj ping was written for a PingRequestHandler that is not included in the trunk code. The ping in trunk is a .jsp file and does not respond to standard request parameters (wt=xml).
To fix this, I think the best thing is to add a PingRequestHandler that does the same thing as ping.jsp.
I don't have time now to fix it, but I'll open a JIRA issue so it is not lost.
ryan