tables, essentially arrays
Sorry, but to be brutally honest this statement alone suggests a fundamental lack of understanding of a what a database truly does. Normalization, primary and foreign keys, indexing, transactions, column/row locking, query optimization, inner/outer joins, referential integrity, manage data spread across multiple-servers, security, and a whole lot more. A database is a lot more than a 'bunch of arrays'.
It would seem a lot easier to just develop a database (not that hard of a project), and use a common HTTP interface for data transfer
I recommend then, to give it a try. There are API's that do this with several different underlying databases, but one must take into consideration not only in transferring secure data but also protecting from insecure transactions