How to correctly organize a request to the data of a third-party system?

Question

API

Now there is a bunch of SD - Mobile application for an employee (application executor).
SD is bulky and clumsy from HP. Somehow, an API is attached to it, which is now working.
Now there is a problem of write-off of goods and materials on applications. It is planned that the contractor will receive goods and materials in the warehouse from the storekeeper who works in another system (1C). In SD, there is no such thing as a spare part or goods and materials from the word at all, and it is not possible to stick it there.
The entry point for the application is strictly one - this is SD (party policy / security guards and all that).
Question - how best to update the data on goods and materials for an employee in the application?
sort of like option 2
- set up some kind of integration from 1s -> to SD by event (let's say issuing goods and services)
- hack the API in 1C and pull from the SD API 1C

Answer 1

hack the API in 1C and pull from the SD API 1C

Such an option is possible. If the SD can make HTTP requests, then you can use HTTP services or WEB services.