DOD and VA have had problems integrating their health care IT systems. Now they've focused on a "Joint Legacy Viewer", which uses the principle of "write locally, read globally".
As is often the case, I think back to the 1990's (old geezers live in the past, you know) and the idea of integrating the USDA farmer service agencies, at least in their IT. At that time our (my) focus was always creating one database to serve the agencies. In retrospect that was wrong.
In 1992 we were demoing a mocked-up viewer of ASCS data. Maybe we should have tried to build on that, rather than going for the big top-down solution.