[searchisko-dev] Providers, rivers, POST /content/{type}/{contentId}

I'm very confused by what all the things in $subject are. When do you use one over the other? Are they all used to put data into the dcp? I think I'm missing the big picture of how everything fits together in order to make any sort of useful discussion about where I need to go to accomplish what I want to do when talking about adding the meta data about quickstarts into the dcp.