I felt the context was adequately explained at the start of the second paragraph:
I was talking to a friend the other day about content distribution networks online.
By this I mean a graph of interactions between people publishing the content and people consuming the content.
Which (with my prior context) I read as someone publishes the content and then maybe you need to do some cache invalidation somewhere, reheat the current page - maybe you need to reheat some archive pages, the homepage, etc
Something along the lines of
> By this I mean a graph [assumed 'buzzword'] of interactions [that happen] between [as in time] people publishing the content [POST] and people consuming the content [GET]
I mean even the images being used sorta look like something you might end up with if you were to diagram a CDN