When I use ETags, I'll generate the ETag value once (on startup), then cache and serve that value. When the resource changes, regenerate the ETag value. Obviou

When I use ETags, I'll generate the ETag value once (on startup), then cache and serve that value. When the resource changes, regenerate the ETag value. Obviously doesn't work if you're using ETags on dynamic resources, but works well for non-dynamic, but unpredictably frequently changing resources.