To implement a conformant Blu-ray player, you need to implement something called BDJ, or Blu-ray Disc Java. This means that Blu-ray menu systems and special features are implemented as Java ME Xlets.

The specification requires that players provide local storage and network access to the content, alongside a standard UI toolkit and BDJ process management routines. This is intended to be used for optional content, like subtitles in obscure languages and advertising.

This is a physical media format that requires an implementation of Java ME and network access. Let that sink in.