Dictionary or interface?

Hey there!

I'm a co-editor of the Web MIDI API spec and I'm having a bit of a problem
with how to define something.

In the spec, we have a MIDIMessage interface [1], that can be either
machine-generated (coming in from a device) or created by the user using
MIDIAccess::createMIDIMessage [2]. What I'd like to do is get rid of the
whole createMIDIMessage and make the MIDIMessage a dictionary so that
developers could just pass an object that looks like a MIDIMessage to
methods that take one as an input. However, the MIDIEvent interface [3]
contains a collection of MIDIMessages, so I'm not sure how that would work
if MIDIMessage is a dictionary.

Any ideas? Thanks for the help.

Cheers,
Jussi Kalliokoski

[1]
https://dvcs.w3.org/hg/audio/raw-file/tip/midi/specification.html#idl-def-MIDIMessage
[2]
https://dvcs.w3.org/hg/audio/raw-file/tip/midi/specification.html#widl-MIDIAccess-createMIDIMessage-MIDIMessage-short-status-short-channel-DOMHighResTimeStamp-timestamp-Uint8Array-data
[3]
https://dvcs.w3.org/hg/audio/raw-file/tip/midi/specification.html#idl-def-MIDIEvent