JSS App Import API
In some situations, JSS applications must be developed disconnected from Sitecore using the code-first development workflow. Such applications must eventually be connected and deployed to Sitecore to be able to take advantage of Sitecore features.
The App Import API enables developers to import such applications into Sitecore, creating the item infrastructure necessary to run the application when connected.
App Import Service
The App Import Service is part of the suite of services and APIs provided by Sitecore Headless Services and it was created specifically to facilitate the importing of code-first, disconnected JSS apps into Sitecore.
The App Import Service provides an endpoint on the Sitecore Content Management (CM) instance, enabling developers to import an application created and defined structurally while disconnected from Sitecore.
It accepts deployments of JSS Manifest packages from the JSS applications.
The Import Service is automatically disabled on CD servers.
The App Import Service does not import the build artifacts of your JSS app. It only imports Sitecore items for the following reasons:
The production app artifacts must be deployed to the CM and the Content Delivery (CD) instance and the service can not orchestrate this process.
To reduce the attack surface by removing the possibility of modifying files through the deploy service.