You can specify multiple digests for an asset, so a non-versioned one can be updated sans downtime: 1. Provider informs clients that a new version with digest

You can specify multiple digests for an asset, so a non-versioned one can be updated sans downtime: 1. Provider informs clients that a new version with digest X will be deployed. 2. Clients add the new digest in addition to the current digest. 3. Provider switches to new asset version. 4. Clients remove old digest (optional). Versioned assets are obviously better unless you're in a really weird situation, but SRI doesn't particularly require them.