DBMS_XMLSCHEMA commands concurrent executing

Question

Java class methods execute statements 'DBMS_XMLSCHEMA.registerSchema' and 'DBMS_XMLSCHEMA.deleteSchema' on Oracle 9i through JDBC using Jboss 4.0.0.
Several users may request these service simulaneously and the following happens: one or both actions fail; after that records not associated with any registered schema can be found in 'user_xml_schemas' table or node for a schema url exists in the tree (Oracle treat this as the schema is registered) but no correspondent records can be found in 'user_xml_tables' and sometimes in 'user_xml_schemas'; then we cannot register any schema until we stop server and start it again. The methods, which are responsible for DBMS_XMLSCHEMA statements executing, first look up data source by JNDI-name, then call getConnection() of DataSource instance, then try to execute DBMS_XMLSCHEMA statement, e.g."BEGIN DBMS_XMLSCHEMA.registerSchema('some_url', 'some_valid_xsd_as_String'); END;", then close connection.
How can I avoid the situation described above? Or can I somehow prohibit executing any DBMS_XMLSCHEMA commands until a job is done (by Oracle means)?

Answer 1

Sofia,
One possibility:
If you write an Oracle procedure/package and store it in the database, you could call this procedure/package instead of the dbms_xmlschema package. Then test for other sessions active from the user account with a select from the v$session view where username = the username your using. If there is an active session you could terminate the incoming session. If no active session you could then call the dbms_xmlschema package from your package passing it the correct information and execute immediate the registerschema.