The title is "Zur Feier" by Willy Geßler, as GUEST Lin pointed out, and so it appears at ingeb.org (The name of this site seems to derive from the name Ingeborg, b.t.w. The MIDI file given there uses the MIDI sounds of the instruments described).

No one in the other threads claims to know exactly the original, which must have existed since the composer's name is known.