code: private void beginTransaction() {
  
  		if (currentTransaction == null) {
  
  			try {
  				currentTransaction = StructrApp.getInstance(securityContext).tx(true, false, false);
  
  			} catch (FrameworkException fex) {
  
  				// transaction can fail here (theoretically...)
  				logger.warn("Unable to begin transaction.", fex);
  			}
  		}
  	}
docs: ----- private methods -----