How to get Alexa to tell Sonos to access my Local Music

I expected that it would be implemented to the high standards that Sonos has provided in the past. I did not expect Sonos to be brought low by Amazon.

Like everyone else Sonos was wrong footed by Alexa/Amazon, and chose to catch up by combining with Amazon instead of competing via an in house developed solution. Probably the right thing to do in the short term because they lack the scale needed to quickly do so, that which Amazon/Apple/Google have. Long term? I doubt anyone can predict.

Having tied a leg to Alexa it now must not be easy to march to the beat of a different drummer, at least in the short term. That said, it is only the first step of starting music play from the local library that isn't possible: all others including asking Alexa what is playing, are.

While I would have no issue with Sonos having a copy of my index in the cloud, I'm not sure it's necessary?
Currently you can issue a voice command to Alexa (at that point it doesn't even know if Amazon Unlimited has the song?) and Alexa with translate that into a command and will play the song if it has it or will tell you it can't find the song and won't play it.
Why can't that just work with your local index (and considering you would know the contents of your own library, maybe with even more success?)?
Issue the command to Alexa and it tells Sonos what to play. If it finds it cool. If not it fails.

The other reason why this isn't possible at this time is that Amazon may have put in a hopefully short term veto to this to see if they pick up Amazon Music subscriptions from us.

Yes, they 'MAY' have done that but that is supposition.
I'm querying the assertion that the index would need to be held in the cloud or that it's technically sophisticated to allow control of the local index and am trying to understand why.

So the integration is fairly useless i would say. Pull your finger sonos. If i can access my libraries from my iphone why not alexa??

Because all Alexa processing is done in the cloud, and unlike streaming services, there is no index of your local music available in the cloud, nor any existing way for Alexa to query local music. Sonos and Amazon would have to allow for storing a local index in the Amazon cloud, or develop a sophisticated back and forth between Sonos and Alexa to enable Alexa to query Sonos about its index, all while maintaining a short response time when requesting music. Not at all easy, nor (I imagine) a priority for Amazon at this time.

Sonos does index your music files from your library, and I imagine the 'cloud' is where this index is kept, and possibly a local copy too, this index must now be shared with Amazon, or at least Alexa has access to this index.

I created my own mix, with my name as the artist and Alexa still knows what song/artist is playing from my music library when asked, and obviously, I'm not listed as an artist on Amazon music or any other music service.

So Alexa clearly can and does query local music, at least an index of it.

This is encouraging on the one hand, as I imagine it wouldn't be too much work to allow local music to be a source that Alexa can play from, but also worrying, as allowing people to listen to their own locally stored music would negate the need for paying to stream music from Amazon etc, so not really in their interest to do so.

I just hope that this isn't a sign of things to come with Sonos, and that local music playback won't be phased out any time.

I just hope that this isn't a sign of things to come with Sonos, and that local music playback won't be phased out any time.
About a year ago, Sonos announced that over 80% - or was it more - of listening to Sonos was via streamed services, so draw your conclusions from that. This was when they declared a shift of focus to these and to voice control based integration with home automation.

Now I don't see local music being phased out; the Alexa adds that have been done to it are a sign of that, but logically developments there will not have the highest priority, one would think.

Sonos does index your music files from your library, and I imagine the 'cloud' is where this index is kept, and possibly a local copy too, this index must now be shared with Amazon, or at least Alexa has access to this index.

I created my own mix, with my name as the artist and Alexa still knows what song/artist is playing from my music library when asked, and obviously, I'm not listed as an artist on Amazon music or any other music service.

So Alexa clearly can and does query local music, at least an index of it.

This is encouraging on the one hand, as I imagine it wouldn't be too much work to allow local music to be a source that Alexa can play from, but also worrying, as allowing people to listen to their own locally stored music would negate the need for paying to stream music from Amazon etc, so not really in their interest to do so.

I just hope that this isn't a sign of things to come with Sonos, and that local music playback won't be phased out any time.

Sorry, but you couldn't be more wrong. The index is kept on the Sonos players and only the Sonos players, not in any cloud.

As to local music being phased out, Sonos has no need to phase it out, it is happening naturally. When Sonos last published the numbers a few years ago, streaming online was 92% of all usage on Sonos. Local music was a mere 8%, and I'm sure it is lower by now.

Well I just disconnected my router form the internet, but left wifi connected and all devices still connected via wifi, and then played a locally stored music track using the sonos controller app.

I then asked Alexa "what's playing" but it just responded by saying it could not connect to the public internet.

I then reconnected the line to the router to enable internet access again and then asked Alexa what was playing, oddly it responded by saying the title/track that was playing before I disconnected the internet connection.

I'm not exactly sure what this proves, if anything! but what it does show is that unless playback of a locally stored music track is first initiated before the internet is disabled, then Alexa then has no idea what is playing locally, even after the connection is re-established during playback.

I just asked Alexa to stop, and then resume and then it correctly identified what was playing.

https://en.community.sonos.com/music-services-and-sources-228994/where-is-my-music-library-actually-stored-is-it-on-my-hardware-or-with-sonos-6329819