What is the {directory service} with the {MAX(port)} whose {instance of} is {directory service}  ?
What benefit with the biggest harbour may be a directory?
What service with the largest port is a directory?
SELECT ?o WHERE { ?o rdf:type ontology:directory_service . ?o property:port ?e . ?o rdf:type ontology:directory_service }
select ?ent where {
?ent <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q756230>.

?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?ent .
?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1641>.
?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj1.

?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?ent .
?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P31> .
?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q756230> .

}
ORDER BY DESC(?obj1)
LIMIT 5
select ?ent where { ?ent wdt:P31 wd:Q756230 . ?ent wdt:P1641 ?obj . ?ent wdt:P31 wd:Q756230 } ORDER BY DESC(?obj)LIMIT 5 
Lightweight Directory Access Protocol