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I'm trying to port a web application to a native Android application using Cordova. It's fairly simple, primarily just sending Midi messages to a connected device. I know the WebMidi API is only supported on recent versions of Webkit on Android, and I have been testing on 5.1. I've managed to prove that the basics work by running the original web version on Chrome on the device, it works fine.

The problem when running in Cordova is the messages themselves are not sent for some reason, no error, just not getting there. I know the API is working, as a separate part of the application lists the connected devices and presents a dropdown list to choose from, this works fine, and recognises the connected Midi device. However, when I send messages they don't have the desired effect on the Midi device. They are SysEx messages, which I believe needs additional permissions, android.webkit.resource.MIDI_SYSEX, is it possible that this is enabled on Chrome but not on the Cordova application? I've tried adding this permission to the ./config.xml, and ./platform/android/AndroidManifest.xml but to no avail, it doesn't seem to have any effect, and doesn't even show as an additional permission when installed.

Based on various searches, I've also tried installing the Crosswalk plugin, but couldn't get that to work at all, not even the device listing.

Any thoughts welcome.

Paul Gregory
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The problem you're facing is that you won't even be prompted for midi sysex permission unless you meet certain criteria. You either have to be accessing your web midi code via a localhost, OR on an https URL. Sysex is potentially harmful, so they have used this as a minimum security requirement.

I had it working on android by opening a URL on my to my dev PC (using a self signed SSL cert on wamp). It gives the security prompt for sysex and then works as expected, so chrome on android works for sure. Crosswalk Cordova however, I'm not so sure.

I've tried running a little webserver in my cordova app (on Android), starting the webserver on 127.0.0.1:8080 and then connected to it using chrome (separately on the same device). Feels tantalizingly close, but I need it to run in my app!

My attempts to run an iFrame with the webserver's URL (http://127.0.0.1:8080) have failed. it's just not found. No security error, so doesn't seem to be to do with white-listing, although I need to look into that further to be sure.

It seems that the webserver plugin is running successfully, but is not visible from within the app.

You should have a play with this, and see if it gets you anywhere...

Or perhaps you'll find another one that is visible from within the app itself. The alternative approach is to use a socket server to connect to your computer, and have the midi devices connected to it. Not exactly portable though!

Tolli
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