[Gnumed-devel] Reason for backend complexity

[Horst Herb]

The main reason why we had to split the monolithic backend up:
- some countries provide centralized demographic information. It would 
be inefficient and unreliable to try to copy such a centrally well 
maintained demographic database. We should rather allow to tap into it 
via distributed services.
- some countries provide centralized pharmaceutical information
- some countries provide centralized immunisation databases
- some conutries centralize certain pathology results
etc.

Sometimes, this happens on a smaller scale like within a hospital where 
hey already have successfully implemented some of these services, they 
are running smoothly, and they find no reason to pull it apart again. 
GNUMed will shine in such an environment because it will be far easier 
to integrate into such existing solutions than other software.

Thus we try to find out which "services" are relatively independent from 
 others, and isolate them into particular "virtual" databases. That 
way, it will be magnitudes easier to write simple wrappers for external 
sources and use them.

The main obstacle is tha Postgres in itself does not support 
cross-database queries, and we have to take care of referential 
integrity between external sources ourselves.

Horst