MobiLink Synchronization User's Guide
Synchronization Basics
The synchronization process
The MobiLink synchronization server incorporates changes uploaded from each MobiLink client into the consolidated database in one transaction. The MobiLink synchronization server commits these changes once it has completed inserting new rows, deleting old rows, making updates, and resolving any conflicts.
The MobiLink synchronization server prepares the download stream, including all deletes, inserts, and updates, using another transaction. By default, it does not commit this transaction until it receives a positive confirmation from the MobiLink client. If the client confirms a successful download, the MobiLink synchronization server commits the download transaction. If the application encounters problems or cannot reply, the MobiLink synchronization server instead rolls back the download transaction.
Do not commit or roll back transactions within a scriptCOMMIT or ROLLBACK statements within scripts alter the transactional nature of the synchronization steps. If you use them, you cannot guarantee the integrity of your data in the event of a failure. There should be no implicit or explicit commit or rollback in your synchronization scripts or the procedures or triggers that are called from your synchronization scripts. |
The primary role of the download transaction is to select rows in the consolidated database. If the download fails being sent to the remote, the remote will upload the same timestamp over again, and no data will be lost.
The MobiLink synchronization server uses two other transactions, one at the beginning of synchronization, and one at the end. These transactions allow you to record information regarding each synchronization and its duration. Thus, you can record statistics about attempted synchronizations, successful synchronizations, and the duration of synchronizations. Since data is committed at various points in the process, these transactions also let you commit data useful when analyzing failed synchronization attempts.
Similarly, the MobiLink client processes information in the download stream in one transaction . Rows are inserted, updated, and deleted to bring the remote database up to date with the consolidated data.