File-Update Synchronization

File-Update Synchronization

In its simplest form, file-update synchronization is a means of ensuring that all users have the latest copy of a file. File-update synchronization services can manage files by monitoring the date and time stamps on files to determine which files were saved most recently. By tracking the users who access the file, along with the date and time stamps, the service can update all the copies of the file with the most recent version.

File-update synchronization, however, can be considerably more involved. In a modern computing environment, it is not always feasible for all users to access all files in real time. A salesman, for example, might carry a notebook computer on which to enter orders. Dialing the central LAN every time an order was to be entered would be impractical, so the salesman would enter orders offline (while disconnected from the network) and store them in the laptop. That evening, he would call the central LAN, log in, and transmit all the day’s orders at once.

During this process, files on the LAN must be updated to reflect new data in the salesman’s portable computer. In addition, the salesman’s PC might need to be updated, for example, with order confirmations or new pricing information. The process of bringing the local and remote files into agreement is also known as file-update synchronization.

File-update synchronization becomes considerably more challenging when additional users are sharing data files simultaneously. Complex mechanisms must be in place to ensure that users do not accidentally overwrite each other’s data. In some cases, the system simply flags files that have multiple, conflicting updates and require a human to reconcile the differences. In Windows 95 and NT 4.0, the My Briefcase program provides this service.