Add Uniform Type Identifiers for MusicXML files

[mdgood]

Martin Dawe suggested it would be useful for MusicXML compressed (.mxl) and uncompressed (.xml) files to have Uniform Type Identifiers for use on iOS and Mac systems:

We are updating NotateMe (our new iOS/Android handwritten notation app) to open MusicXML files sent directly from other apps running on a device (using 'Open In').

On iOS, this requires NotateMe to register its support of the MusicXML file type with a Uniform Type Identifier (UTI), and it seems official UTI types do not exist for MusicXML and compressed MusicXML (although I suppose we could use the XML UTI 'public.xml' for non-compressed files).

The UTI that Neuratron developed uses the com.recordare.musicxml naming based on the current MusicXML MIME types. We may want to update both the UTI and the MIME types to reflect the move to the W3C, so this issue is related to the MIME type issue #51.

See the MusicXML forum discussion at http://forums.makemusic.com/viewtopic.php?f=12&t=2510.

[mdgood]

For MusicXML 3.1, I suggest we update to using W3C-based name. We can also be more specific about the conformance of compressed and uncompressed files. I'd like to specify this in a way that could work both as a community group and potentially in the future as a working group. I suggest updating Martin's proposal referenced above to:

<key>UTImportedTypeDeclarations</key>
<array>
    <!-- Uncompressed MusicXML -->
    <dict>
        <key>UTTypeIdentifier</key>
        <string>org.w3c.music-notation.musicxml.uncompressed</string>
        <key>UTTypeReferenceURL</key>
        <string>http://www.musicxml.org/</string>
        <key>UTTypeDescription</key>
        <string>MusicXML File</string>
        <key>UTTypeTagSpecification</key>
        <dict>
            <key>public.filename-extension</key>
            <array>
                <string>xml</string>
            </array>
            <key>public.mime-type</key>
            <array>
                <string>application/vnd.recordare.musicxml+xml</string>
            </array>
        </dict>
        <key>UTTypeConformsTo</key>
        <array>
            <string>public.xml</string>
        </array>
    </dict>
    <!-- Compressed MusicXML -->
    <dict>
        <key>UTTypeIdentifier</key>
        <string>org.w3c.music-notation.musicxml</string>
        <key>UTTypeReferenceURL</key>
        <string>http://www.musicxml.org/</string>
        <key>UTTypeDescription</key>
        <string>MusicXML File</string>
        <key>UTTypeTagSpecification</key>
        <dict>
            <key>public.filename-extension</key>
            <array>
                <string>mxl</string>
            </array>
            <key>public.mime-type</key>
            <array>
                <string>application/vnd.recordare.musicxml</string>
            </array>
        </dict>
        <key>UTTypeConformsTo</key>
        <array>
            <string>public.zip-archive</string>
        </array>
    </dict>
</array>
<!-- end UTImportedTypeDeclarations -->

The MIME types would change if we decide to update them as part of issue #51.

I left the URL as www.musicxml.org because I don't know a more stable URL to use. The community group URL would change if we move to a working group. The GitHub URL that holds the spec might change if the W3C moves to a different source code management technology in the future.

I don't know how many applications outside of Neuratron are already using Martin's earlier UTI proposal for MusicXML 3.0. If there is a lot of usage already perhaps it may make sense to leave the older names in place. We might wind up doing that for issue #51 if the benefit of changing the media types does not seem to be worth the cost.

Comments and suggestions are most appreciated!

[mdgood]

I suggest that we document these UTIs in the container.dtd file, where the media types are already documented.

[mdgood]

The group consensus at the Musikmesse meeting was to go ahead with this proposal, using the W3C names and application/musicxml and application/musicxml+xml media types.

[mdgood]

After reviewing RFC-6839, it seems best to have the compressed MusicXML file use the application/musicxml+zip media type.

Also, in conjunction with issue #191, the uncompressed filename extension will be updated from xml to musicxml.

[mdgood]

Pull request #206 addresses this issue.

[mdgood]

As mentioned in issue #51, we will not be able to move the media type to the standards tree at this time. We will need to update the UTI definition to the media types in the vnd tree as originally proposed.

[mdgood]

Pull request #211 reverts back to the current media types. The UTTypeIdentifier names also revert back to Martin Dawe's initial proposal, so as to be consistent with the existing media type names.

[mdgood]

If we decide to go back to the .xml suffix for uncompressed MusicXML files as discussed in issue #191, that will be reflected in the UTI definition as well.

[mdgood]

We are staying with the .musicxml extension for uncompressed MusicXML files, so there is nothing to change here.