Create rfc.md

Author: oblomov-dev

docs/advanced/rfc.md

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+# RFC Connector
+
+The abap2UI5 RFC Connector allows you to trigger abap2UI5 apps remotely via RFC between two ABAP systems. This is particularly useful in distributed system landscapes or when working with legacy systems that cannot directly host UI5 frontend logic.
+
+#### When to use
+The RFC Connector enables several useful scenarios:
+- Frontend/Backend Split: abap2UI5 apps are implemented in the backend, but users only have access to the frontend server
+- Legacy Systems (e.g. ECC): abap2UI5 can be downported and installed on older systems and then triggered from a newer system via RFC
+- Multi-System Landscapes: abap2UI5 apps distributed across multiple systems can be accessed centrally from a single entry point
+
+
+#### Architecture
+
+The system that calls the app (the frontend system) includes the UI5 library and bootstraps the UI. The system where the app is implemented (the backend system) does not need to host the UI5 runtime.
+
+<img width="600" alt="1719296908473" src="https://github.com/user-attachments/assets/6f885f04-2b70-4cb3-83d0-123473b72262" />
+
+
+#### Installation
+
+_Prerequisite: Set up a destination in SM59 that the source system can be called via RFC. abap2UI5 need to be installed in both systems._
+
+Steps:
+1. Install the [abap2UI5 RFC Connector](https://github.com/abap2UI5-addons/rfc-connector) via abapGit on both system
+2. Replace in the HTTP handler the destination `NONE` with your Source System Destination
+3. Call in your browser the endpoint `.../sap/bc/2ui5_rfc`
+
+#### UI5 Bootstrapping
+The backend system that holds the abap2UI5 apps does not need to include the UI5 libraries. These are automatically bootstrapped from the calling system:
+
+<img width="600" alt="1719296975220" src="https://github.com/user-attachments/assets/8e7dd3dd-abd3-413f-8ec6-8a7a2be7a7ec" />
+
+
+#### Multi-System Launchpad
+You can also use this approach to build a centralized Fiori Launchpad that includes both:
+- Apps installed on-stack (on the current system)
+- Apps executed remotely via RFC from other systems
+
+<img width="700" alt="1719297067700" src="https://github.com/user-attachments/assets/a010440d-bd82-46f9-b597-c3ad2273dbde" />