Today, most “conversational agent” (aka chatbot) knowledgebases are either hand tooled, for instance by domain experts, or “crowd sourced” by recycling human responses. There are no ready made or turnkey engines available that allow for dynamically modifying the knowledgebase in realtime, for instance via backend API. The problem with “big data” is that it is by very definition too big to work properly in any conventional database system or hardware platform…. See my recent blog post Dissecting the Summarization Process for some of the nitty gritty involved in doing just this. Otherwise, read through my Quora answers and questions for a veritable primer at Marcus L Endicott.