Patent ID: 7051064

Claim:
A transmitting apparatus for transmitting a hierarchical structure of a directory of a first system for hierarchically managing locations of contents data, comprising: managing means for managing the hierarchical structure of the directory composed of a container entry and a leaf entry, a container entry containing information in the immediately lower hierarchical level thereof, a leaf entry being disposed in the immediately lower hierarchical level of a container entry, a leaf entry not containing information in the immediately lower hierarchical level thereof, said managing means operatively configured to rebuild a hierarchical structure with only differential information that is required at least in the directory structure; detecting means for detecting a change in the hierarchical structure of the directory managed by said managing means and obtaining first difference information and second difference information, the first difference information being the difference of container entries corresponding to the detected result, the second difference information being the difference of leaf entries corresponding to the detected result; and transmitting means for transmitting the first difference information and the second difference information to a second system; and for transmitting third difference information representing an overall structure of the directory to a second system for reproducing on the second system the hierarchical structure of the directory, the third difference information being transmitted at intervals of a predetermined time period.