code: protected void initialize() throws Exception {
  		// create the operator
  		try {
  			this.driver.setup(this);
  		}
  		catch (Throwable t) {
  			throw new Exception("The driver setup for '" + this.getEnvironment().getTaskName() +
  				"' , caused an error: " + t.getMessage(), t);
  		}
  		
  		this.runtimeUdfContext = createRuntimeContext(getEnvironment().getTaskName());
  		
  		// instantiate the UDF
  		try {
  			final Class<? super S> userCodeFunctionType = this.driver.getStubType();
  			// if the class is null, the driver has no user code
  			if (userCodeFunctionType != null) {
  				this.stub = initStub(userCodeFunctionType);
  			}
  		} catch (Exception e) {
  			throw new RuntimeException("Initializing the UDF" +
  				e.getMessage() == null ? "." : ": " + e.getMessage(), e);
  		}
  	}
docs: --------------------------------------------------------------------------------------------