passing a document inside a json structure to an appian web api

Hi

I'm trying to implement an Appian Web API (POST method) that is exposed to an external system.
This API capture data like passing a document inside a json structure to an appian.
My question is how to impletement passing a document inside a JSON structure to an appian web API?
Is it possible to implement it in appian web API?If not is there any other way I can implement it?

Please share any relevant documentation or sample code reference.


Thank you