I think this is acceptable.

I know this is NOT the case with GPL 2 and of course not with commercially compatible licensed such as LGPL, Apache, MIT, BSD and a myriad of other licenses as well.

Let’s assume there’s a server software like a database under GPL2. The protocol cannot be GPLed so if you write some driver to interface it without linking GPL licensed code you are free to choose whatever license you want for your driver. Another example is a data exchange happening through stdin/stdout: If you interface a GPL2 application in such a way then it is considered a public interface that cuts the GPL at that point.

Some people didn’t like that because this is a common way to circumvent the legal restrictions of GPL without breaking it (which is okay since they had a point). The big difference between AGPL and GPL is that AGPL claims any interface to be under AGPL restrictions such as network communication or stdin/out. Although you don’t link directly to a AGPLed codebase you are still forced to license your code under either AGPL or at least GPL.

I think that MongoDB’s core developers got confused with those licenses. What they claim MongoDB to be licensed under matches GPL2 but definitely not AGPL since the whole point of AGPL gets lost.

To get back to your example, theoretically, if you are interfacing an AGPLed server via HTTP, AGPL would spread through that channel as well, to those MongoDB drivers that are working with REST, to your own driver that you wrote because you felt the urge to and so on. Of course that’s highly unpractical and unrealistic, that’s just not the way any open system works. But that’s how AGPL has been intended to be; I’d like to call that some sort of broken design.

Martin: that is just ignent. That has never been how GPL software works. The rule has always been: what are you directly linking to? Or more to the point, if you did a monolithic compile, what code goes into your app. For some reason, people seem fond of not using the LGPL, but adding “Exceptions” to GPL code (see MySQL, Java, etc). But if passing data to/from a GPL application affected your code, the whole of the web would be “infected.”

“Note however that it is never required that applications using mongo be published. The copyleft applies only to the mongod and mongos database programs. This is why Mongo DB drivers are all licensed under an Apache license. Your application, even though it talks to the database, is a separate program and “work”.”
http://www.mongodb.org/display/DOCS/Licensing