I'm perfectly happy with REST and have several APIs for other things already in production using REST::Application and REST::Client. So, if there isn't already something on CPAN to do this that is very likely to be the way I would go.

The question was more intended to be that the general problem (irrespective of JSON or REST or whatever) of requesting a list of records since some timestamp, ordered by timestamp, has probably already been solved. So let's just use that instead of re-inventing the wheel.

Of course, if it turns out that there isn't an implementation on CPAN I might as well publish the one I write.

While typing this, one thought has occurred which is that there might be an RSS implementation which could be made to do this. I will have another dig.