Patent ID: 7636728

Claim:
A method for generating from a server a difference (DIFF) catalog file for catalog files, said method comprising: generating a first catalog file listing media files without contents of the media files; generating a second catalog file, said second catalog file being an updated replacement of the first catalog file including a modified portion of the first catalog file, said modified portion indicating a difference between the content of the first catalog file and the second catalog file, said first catalog file and said second catalog file each including an array with reference identifiers identifying only one occurrence of words used in identifying the media files; receiving a request from a client device for identifying one or more of the media files; determining whether the client device has previously stored the first catalog file; determining that the client device has not previously stored the first catalog file, transmitting the generated second catalog file to the client device; determining that the client device has previously stored the first catalog file, comparing the generated second catalog file with the generated first catalog file to identify at least the modified portion in the second catalog file; identifying a location of the modified portion in the content of the second catalog file; assigning a reference marker to the identified location with respect to the second catalog file; generating the DIFF file indicating the modified portion and indicating the reference marker; and transmitting the generated DIFF file to the client device to be stored on the client device, wherein the client device executes the generated DIFF file and the first catalog file to generate an identical version of the generated second catalog file such that the second catalog file is stored on the client as a replacement of the first catalog file on the client device.