Improved API to read metadata and lineage for library items

From my external application, I want to call a Spotfire Library API (preferrably REST) to read metadata for library items and their dependencies.

This can be seen as an enhancement to the current LibraryService API (SOAP), but more detailed metadata is needed for each specific library item type (analysis file/dxp, data connection, data connection data source, information link data source etc.).

Today, I struggle by mixing various techniques and APIs (LibraryService (SOAP) for lineage and basic metadata, Automation Services custom task (C#) for detailed analysis file metadata etc), which is cumbersome and have limitations. It would be nice to have everything (lineage and all relevant metadata) accessible in one API, easily consumable from a web application.