Access external database in AX R3

Hi all,
We have a customer that is upgrading from Axapta 4.0 to Dynamics AX 2012 R3. One of their custom solution requires communication with an external SQL database, both reading and writing data.

Today this is accomplished in Axapta with the System.Data.SqlClient namespace. The database and AOS are on the same network.

Without going into too much details about the requirement, my question is if anybody has some ideas of better ways, or if possible to use AIF in some sense for accessing external database in Dynamics AX R3.

Let the brainstorming begin.