Why is conflict free data synchronization so difficult?
There are lots of reasons why it is hard, but the biggest is that it is defect sensitive. Even one small defect (something that in other software could be a corner case) can corrupt your entire operation stream. To ensure that the core engine is bug free is definitely one of the hardest tasks of the beWeeVee team. Just to put it in context, the testing robot that implements the die-hard tests required to pass for every release takes 17 hours on a quad core computer.
