3645490 - FLP@XSA _ some updates for reverse proxy system

Background Information on the subject: 

In on-premise WEBIDE SP08 patch 02 was to add support for running WebIDE in reverse proxy environment with external domain and fallback functionality.

Using SAP Web IDE on-premise with XS Advanced (XSA) behind a reverse proxy means developers access the system through a single external domain, while the proxy securely routes traffic to internal XSA hosts. 
The setup supports fallback across multiple hosts, so if one host fails, the proxy automatically redirects traffic to another, ensuring high availability.
Applications typically expose both an internal URL (used for routing inside the XSA landscape) and an external URL (used by clients); the client only needs to provide a short/partial URL, which the proxy then translates into the correct full internal URL.
This abstraction simplifies client access, hides internal network complexity, and ensures consistent and reliable application availability.

For more details, see:

• SAP Help: Using a Reverse Proxy with an External Domain
• SAP Help: Setting Up XS Advanced Runtime Behind a Reverse Proxy

Here’s a simple diagram:

• The client sends only a partial URL to the reverse proxy using the external domain.
• The reverse proxy expands and routes that request into the full internal URL, directing it to one of the available XSA hosts.
• If one host is unavailable, the proxy can seamlessly forward the request to the fallback host, ensuring continuous service.

This way, the client never needs to know or use the internal URLs—the complexity is handled entirely on the server side.

Problem:
In the reverse proxy environment, the FLP template application was unable to load the UI5 libraries, which caused the application to fail to start.

FLP@XSA 

FLP@XSA，reverse proxy system, Web IDE, WebIDE, SP08, Patch 02, environment, external domain, fallback , KBA , BC-XS-SRV-PTL , Hana XS Advanced Portal Services (for Fiori Launchpad) , Problem