Webservice can be a website of course. On sql prompt (sqlplus / as sysdba)

begin
  dbms_network_acl_admin.create_acl (
  acl => 'webservice.xml',
  description => 'permissions to access webservice',
  principal => 'SCOTT',
  is_grant => TRUE,
  privilege => 'connect');
  commit;

  dbms_network_acl_admin.add_privilege(
  acl       => '/sys/acls/webservice.xml',
  principal => 'SCOTT',
  is_grant  => TRUE,
  privilege => 'resolve');
  commit;

  dbms_network_acl_admin.assign_acl(acl  => '/sys/acls/webservice.xml', host => 'asterix');
  dbms_network_acl_admin.assign_acl(acl  => '/sys/acls/webservice.xml', host => 'asterix.bretagne.fr');
  commit;
end;
/