Problem
By default, Oracle XE will set its web-based DBMS to use 8080 port, which conflicts with default port of some web servers e.g. JBoss, Tomcat.
Solution
begin
dbms_xdb.sethttpport('18080'); -- Change to port 18080
end;
select dbms_xdb.gethttpport from dual; -- View the port
You need a SYSTEM (or DBA) user account to change the port.