US Patent 7358856 Two-phase commit synchronizing seal state

A conveyance tracking system provides two-phase transaction commit processing for synchronizing seal state information between a seal device attached to a conveyance and a host for tracking conveyances. The system uses a reader device for synchronization and communication between the seal device and host system regarding various operations, such as a lock operation, an unlock operation, and a clear tamper operation. In the first phase of the two-phase commit, the seal device prepares for the operation and the host executes the operation. In the second phase, the seal device fulfills the irreversible operation, ensuring that the seal state of the seal device and host are in sync.