A locking mechanism for securing a jumper tube to a shunt tube in a well screen assembly for use in gravel packing features a jumper tube having a telescoping connector that extends to engage the shunt tube and a locking mechanism that extends the connector the proper distance and then locks the connector into place by engaging lugs that are connected to the jumper tube. First, a data slice signal is generated according to the RF signal read by the optical pickup head of the optical disk drive, and the data slice values, reflecting the central levels of the RF signal, of the data slice signal at the beginnings of the header area and data area are preset. A device context is determined with the context service module using context information that is provided by multiple different context providers.