Arhitecture for external .Net services to communicate with interna

[Lorents Nord-Varhaug]

What is needed, if possible, to set up an environment where we can place .Net
services on the external side of the firewall (reacahable for our internet
server), that can communicate and retrieve data throug .Net services on the
inernal side of the firewall?

Currently, the few solution our company have where external partners are
able to search data from internal databases, is solved by replicate the
needed content from an internal database, to an external server.

Now we keep getting an increasing number of request from our colegues of
establising solutions where we would like to have the option of requesting
data from internal databases, directly from our internet server.

In some situations, we need to makesoltuions where we know the external
users, like a customer might request wheter a specific product is in stock.
In such situations we might use certificates or requires our external users
to be able to identify themelves. But we also have requests for solutions
where we should be able to have anonymous users requesting data, which we
would like to retrieve directly from an internal database.

Any suggestion of where to look for articles/books etc., where we can get
som information of how to solve such requests?