public DbMapping (Application app, String typename, SystemProperties props) {  this.app = app; this.typename = typename;
public DbMapping () {
    public DbMapping (Application app, String typename, SystemProperties props) {	this.app = app;	this.typename = typename;	prop2db = new Hashtable ();	db2prop = new Hashtable ();	parent = null;	subnodes = null;	properties = null;	idField = "id";	this.props = props;	update ();	app.putDbMapping (typename, this);    }