---+++Discussion Data Space
<verbatim>
PREFIX sioc: <http://rdfs.org/sioc/ns#>
PREFIX sioct: <http://rdfs.org/sioc/types#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?forum_name, ?post, ?mbox
WHERE 
  {
    ?forum a sioct:MessageBoard .
    ?forum sioc:id ?forum_name.
    ?forum sioc:container_of ?post.
    optional{ ?post foaf:maker ?maker }.
    optional{ ?maker foaf:mbox ?mbox } .
  }
</verbatim>

---+++++Sample Data (Live Query Results)
   * View Query Results [[http://demo.openlinksw.com/sparql?default-graph-uri=&should-sponge=&query=PREFIX+sioc%3A+%3Chttp%3A%2F%2Frdfs.org%2Fsioc%2Fns%23%3E%0D%0APREFIX+sioct%3A+%3Chttp%3A%2F%2Frdfs.org%2Fsioc%2Ftypes%23%3E%0D%0APREFIX+foaf%3A+%3Chttp%3A%2F%2Fxmlns.com%2Ffoaf%2F0.1%2F%3E%0D%0ASELECT+%3Fforum_name%2C+%3Fpost%2C+%3Fmbox%0D%0AWHERE+%0D%0A++%7B%0D%0A++++%3Fforum+a+sioct%3AMessageBoard+.%0D%0A++++%3Fforum+sioc%3Aid+%3Fforum_name.%0D%0A++++%3Fforum+sioc%3Acontainer_of+%3Fpost.%0D%0A++++optional%7B+%3Fpost+foaf%3Amaker+%3Fmaker+%7D.%0D%0A++++optional%7B+%3Fmaker+foaf%3Ambox+%3Fmbox+%7D+.%0D%0A++%7D%0D%0A&format=text%2Fhtml&debug=on][(via SPARQL Protocol URL)]]
   * View Query Results [[http://demo.openlinksw.com/view/?format=application%2Frdf%2Bxml&maxrows=50&query=%0APREFIX%20sioc%3A%20%3Chttp%3A%2F%2Frdfs.org%2Fsioc%2Fns%23%3E%0APREFIX%20sioct%3A%20%3Chttp%3A%2F%2Frdfs.org%2Fsioc%2Ftypes%23%3E%0APREFIX%20foaf%3A%20%3Chttp%3A%2F%2Fxmlns.com%2Ffoaf%2F0.1%2F%3E%0ASELECT%20%3Fforum_name%2C%20%3Fpost%2C%20%3Fmbox%0AWHERE%20%0A%20%20%7B%0A%20%20%20%20%3Fforum%20a%20sioct%3AMessageBoard%20.%0A%20%20%20%20%3Fforum%20sioc%3Aid%20%3Fforum_name.%0A%20%20%20%20%3Fforum%20sioc%3Acontainer_of%20%3Fpost.%0A%20%20%20%20optional%7B%20%3Fpost%20foaf%3Amaker%20%3Fmaker%20%7D.%0A%20%20%20%20optional%7B%20%3Fmaker%20foaf%3Ambox%20%3Fmbox%20%7D%20.%0A%20%20%7D%0A&endpoint=/sparql&maxrows=50&default-graph-uri=][(via iSPARQL Results URL)]]
   * View Query Editor [[http://demo.openlinksw.com/isparql/?query=PREFIX%20sioc%3A%20%3Chttp%3A%2F%2Frdfs.org%2Fsioc%2Fns%23%3E%0APREFIX%20sioct%3A%20%3Chttp%3A%2F%2Frdfs.org%2Fsioc%2Ftypes%23%3E%0APREFIX%20foaf%3A%20%3Chttp%3A%2F%2Fxmlns.com%2Ffoaf%2F0.1%2F%3E%0ASELECT%20%3Fforum_name%2C%20%3Fpost%2C%20%3Fmbox%0AWHERE%20%0A%20%20%7B%0A%20%20%20%20%3Fforum%20a%20sioct%3AMessageBoard%20.%0A%20%20%20%20%3Fforum%20sioc%3Aid%20%3Fforum_name.%0A%20%20%20%20%3Fforum%20sioc%3Acontainer_of%20%3Fpost.%0A%20%20%20%20optional%7B%20%3Fpost%20foaf%3Amaker%20%3Fmaker%20%7D.%0A%20%20%20%20optional%7B%20%3Fmaker%20foaf%3Ambox%20%3Fmbox%20%7D%20.%0A%20%20%7D%0A&endpoint=/sparql&maxrows=50&default-graph-uri=][(via iSPARQL Visual Query Editor URL)]]