[Alug] Sending information between databases

(This isn't a pure linux question, but I hope you can help) What is a good system for sending information between databases, with minimal human interaction? Situation is that someone has a database in one location, another person has another copy. The list of tables/fields between the 2 databases is not exactly the same, but have several tables in common. The two databases could be synched with a lot of human work, but is there a method to do this automatically - perhaps sending XML between the two? Anyone got experience in doing this sort of stuff? Ashley