How to access a web service behind a NAT?

Question

We have a product we are deploying to some small businesses. It is basically a RESTful API over SSL using Tomcat. This is installed on the server in the small business and i

Answer 1

If you want to have a RESTful integration to the client server, a tunnel to the central server that works as a proxy, seems the best approach.

But if this is not a hard requirement, you can let the central server handle the RESTfull stuff and integrate the central server and client server with other middleware. Good candidates would be RMI or JMS. For example, a RMI connection initiated by the client allows the server to do RMI calls to the client.