The Online model for the Large Hadron Collider

The control of the high intensity beams of the CERN Large Hadron Collider is particular challenging and requires a good modelling of the machine. In recent years efforts were devoted to the design of a software infrastructure aimed at mimicking the behavior of the LHC. An online model of the machine, based on the accelerator design tool MADX, has been developed to support the commissioning and the operation of the LHC. This model is integrated into the Java-based LHC development framework and provides the full computing power of MADX, including the best knowledge of the machine aperture and magnetic models. In this paper, we present the status of the MADX online application and illustrate how it has been used during the LHC commissioning. Possible future implementations are also discussed.