I wan't to build a bot that gather its answers and questions from a rest API.
Bot: How are you?
User: I'm fine, how are you?
Bot: I'm fine, also.
So the questions from the bot (even the first one) is gathered via REST API from an external service. Also the answer of the user is sent to this service and the Bots answer "I'm fine, also" is the result of a REST request.
I've first implemented it without using dialog feature at all. Works great, but without a dialog it's impossible to finish a dialog.
Looking around for some example I could only find some with WaterfallDialog. WatefallDialogs are build with steps - and I don't know the number of steps.
Is it possible to build such a dialog or isn't botframework not designed for such things?
In bot framework V4, the dialog/conversation flow you pick for conversations is optional, and you don't need to use them (https://learn.microsoft.com/en-us/azure/bot-service/bot-service-design-conversation-flow?view=azure-bot-service-4.0). All you NEED to do is implement bot state (https://learn.microsoft.com/en-us/azure/bot-service/bot-builder-howto-v4-state?view=azure-bot-service-4.0), so you can store either conversation data (or user data - depends on what state you need.)
I implemented conversational flow using a single activity handler and an FSM (https://en.wikipedia.org/wiki/Finite-state_machine) - I use recognizers for common dialogs (help) but for the most part, my transition handler does regex comparisons to extract keywords and then hit the next state. So, if you can graph out your FSM, and list out all your dialog options, you can build a dialog that appears conversational and natural.
I can't share code at this time, but hopefully you don't need it.