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Oracle XML DB

Check if XML DB is installed

If XML DB is installed, there is a user named XDB (whose status should not be INVALID) and a view named resource_view: 
select status from dba_users where username = 'XDB';
select * from resource_view;

Configuration resource: xdbconfig.xml

xdbconfig.xml is an XML resource used to configure XML DB. This resource is stored in XML DB repository.
The content of the file for the current session can be read with dbms_xdb_config.cfg_get and updated with dbms_xdb_config.cfg_update.
With respect to the embedded PL/SQL gateway, however, the configuration should be made with dbms_epg, not by directly modifying xdbconfig.xml.
The structure of xdbconfig.xml conforms to the XSD http://xmlns.oracle.com/xdb/xdbconfig.xsd

Trace requests

The event 31098 traces requests to the protocol server: 
alter system set event='31098 trace name context forever, level 2' scope = spfile;
alter system set event='31098 trace name context off'              scope = spfile;

TODO

$ lsnrctl status | grep XDB
Service "O21DB1XDB" has 1 instance(s).

See also

Built in type: xmlType.
SQL*Plus: xquery 
select
   *
from
   dba_registry
where
   comp_name = 'Oracle XML Database';

select * from path_view;
dbms_xdb_admin, dbms_xdb_config and dbms_xdb_repos.
dbms_xmlstore
dbms_xmlgen, dbms_xmlquery
XML

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