This is derived from the WP-API (which enables Access to your WordPress site's data through an easy-to-use HTTP REST API). I've stripped out that functionality and added just the ability to upload, validate and process CSV files. This is part of an Admin Console plugin I developed for validating and loading specificic CSVs into the underlying wordpress DB - into another DB Schema.
The WP-API is well documented in the original repo (please check it out). I was creating an Admin Console plugin to allow processing of batch and remittance reports (CSV files). This had to run alongside and already running Wordpress Site and I knew I needed some sort of RESTful API. I found this and decided to use it.
I cracked open the code and read their Extending the APi. I had very little trouble navigating the code and implementing what I wanted.
I wanted to enable uploaing CSVs, Validation, Processing, compressing, moving and deleting. This repo contains contains that.
I ran into difuculty with regards to nonces and authentication. I haven't spent a year working with WordPress, thus i'm not familiar with all the inner workings and subdelties. the API should run within a wordpress app with an anuthenticated Admin account. They describe in their documentation three methods of authentication. Basic authenication worked after installing the correct plugin--in development I used curl for testing. The description of the use of nonces was short and not useful thus I simply hacked it out. This API is secure via obfiscation.