Web service differences between REST and RPC

Question

I have a web service that accepts JSON parameters and have specific URLs for methods, e.g.:

http://IP:PORT/API/getAllData?p={JSON}

This is

Answer 1

I would argue thusly:

Does my entity hold/own the data? Then RPC: here is a copy of some of my data, manipulate the data copy I send to you and return to me a copy of your result.

Does the called entity hold/own the data? Then REST: either (1) show me a copy of some of your data or (2) manipulate some of your data.

Ultimately it is about which "side" of the action owns/holds the data. And yes, you can use REST verbiage to talk to an RPC-based system, but you will still be doing RPC activity when doing so.

Example 1: I have an object that is communicating to a relational database store (or any other type of data store) via a DAO. Makes sense to use REST style for that interaction between my object and the data access object which can exist as an API. My entity does not own/hold the data, the relational database (or non-relational data store) does.

Example 2: I need to do a lot of complex math. I don't want to load a bunch of math methods into my object, I just want to pass some values to something else that can do all kinds of math, and get a result. Then RPC style makes sense, because the math object/entity will expose to my object a whole bunch of operations. Note that these methods might all be exposed as individual APIs and I might call any of them with GET. I can even claim this is RESTful because I am calling via HTTP GET but really under the covers it is RPC. My entity owns/holds the data, the remote entity is just performing manipulations on the copies of the data that I sent to it.