Fabrice,
If you search the support form for "xmlhttp" and "serverxmlhttp" you will see some examples of accessing the API via Visual Foxpro, and others have asked about toolkits like node.js. The full list of entry points (URL resources) to consume via the API can be found here:
http://<your DW server>/DocuWare/Platform/Home/UriTemplatesDocumentation
(online DW documentation appears to not be loading this morning. Grrrr.)
At some point I wish DocuWare would post more generic examples (such as curl), or a Postman package with examples. As far as I know, though, no such pieces of documentation exist at this time. You just need to become familiar with how pythom does GETs and PUTs and POSTs and you should be off to the races.
Thanks,
Joe Kaufman