Almost all external requests made by the client (SciCat Frontend) are done so via NGRX effects within the state management components.
Loopback within the backend provies a generated SDK that is used by the frontend to define all requests to the API. The SDK folder should not be edited because it will just overwrite it when a new one is generated.
The SDK is updated by running the following in the backend source code root:
./node_modules/.bin/lb-sdk server/server.js ../frontend/src/app/shared/sdk
and this is necessary when making any changes to endpoints in the backend.
NGRX is Redux for Angular and is heavily used in the client to manage state.