I need some help with making a REST POST call from my Photon to a web server. The web server requires basic authentication, and the payload of the REST call has to be application/xml.
Does anyone have any example code I could look at to work out the syntax for my REST request?
Checkout this thread: HTTPClient Help (How to "assemble" URI)?
Covers your use case.
REST simply refers to how an API is designed, the actual POST request you are making are a subset of this, and being REST(ful) does not directly say anything about the syntax other than the URL.
For a list of parts in REST see wikipedia : https://en.wikipedia.org/wiki/Representational_state_transfer#Applied_to_web_services
Note that normally you dont send repeating POST requests, you send PUT to update an existing item.
Basic auth is a header, and if you need to set the content-type, thats a header too.
The link @LukeUSMC shared contains some information on their syntax.