I read the announcement post on Signed Exchanges (SXG) but don’t fully understand how they work. I’ve had AMP Real URL enabled for a long time but SXG appears to work differently. This paragraph is useful but yet lacks some detail:
The search engine also preloads the signed exchange for your content in the background in the meantime, effectively pre-filling the cache in the client’s browser. This exchange was delivered from the search engine, so no signal has gone to the origin yet. Thus, the search intent of the user isn’t leaked to the origin. Since the exchange is signed and validated against your certificate, the browser trusts the contents and can display the content with attribution to the original URL. Now, when the user clicks on the link to view the contents, it magically loads instantaneously from the local cache.
- Is this pre-fetched content just HTML or other resources – CSS, JS, Images?
- When the person clicks the link and the page “loads instantaneously from the local cache”, is there no server involved? With AMP (and AMP Real URL) I believe the pages are loaded from Google’s server. If there is a server involved with SXG, is it Google’s server or the Origin server?
- The announcement says during pre-fetching, “the search intent of the user isn’t leaked to the origin”. But when the person does click the link, is the origin aware the page has been displayed in the browser?
- Upon clicking, if the page loads from Google’s server (or from Local Cache with no server), after it has loaded with the origin hostname/URL in the address bar, if the person Refreshes the page (F5, Ctrl-R etc), is the page re-loaded from Google’s server / Local Cache or is it loaded from the Origin server?
Any insight on this is appreciated.