A Mobile Unit Synchronization Algorithm - A Partial Database Synchronization Scheme between a Centralized Server and Mobile Units

Abstract: This report covers the development of a new synchronization module for the Jetas QualitySystems AB. The developers at the company did not appreciate the existing module, based onMicrosoft Synchronization Framework and thus this project was launched. The project firstconducted a literature study to try to find a previously developed model that could be adapted tothe Jetas system. This, unfortunately, was unsuccessful and the project continued with the designof a conceptual model for a synchronization module based on the Jetas systems characteristics.

This model was implemented and enhanced iteratively and functionality added according to theprioritizations done in the requirements specification. The synchronization algorithm itself is anoptimistic timestamp based method. It utilizes the synchronization primitives that are alreadypresent in the Jetas database and used by other parts of the system as well. The selection ofwhich data to synchronize, so as to only do incremental updates each synchronization, is done bykeeping track of the timestamps of the last time a synchronization was performed by that PDAwhile each database row has a timestamp of when it was last changed. Conflict detection isperformed by comparing the timestamps of uploaded and server version of the DataRow inquestion.

The module developed was tested in an office environment, but in this environment it showed aslight improvement in performance even while database indexes are optimized for the previoussynchronization module and several optimizations can be done before this prototype is finalizedfor a production environment. In addition to this, the new synchronization module can easily beextended to implement new functionality, such as multiple users per PDA.