This is a step by step document for implementing Multi-Origin Capability in SAP Fiori Apps.
What is Multi-Origin feature in SAP Fiori Apps?
Multi-Origin is feature in the Fiori Apps through which if a Gateway Service has multiple system aliases defined in gateway configuration, then at run time the gateway service goes to each of the backend system, based on the user’s roles in the backend system and executes the Gateway Service. If you have such a scenario for e.g for a given Fiori Transactional App that you need to show and approve work items from multiple SAP backend systems based on the end user’s roles then this document can be used to help enable that functionality if it is missing. If multiple system aliases are assigned to a Gateway service, then the service will be called in at least the system identified as the default system alias. The Fiori Application’s UI needs certain additional steps to enable Multi-Origin capability.
Please see this link from where you can download the document