A new feature added today to Accelerated Mobile Pages (AMP) integration in Google Search making it easier for users to access, copy, and share the canonical URL of an AMP document that directly lead to publishing sites rather than to Google's copy of the content.
To start with, an AMP documents have three different URLs: original publisher's URL in AMP format, AMP Cache URL, and a Google AMP Viewer URL, that displays the document in an AMP viewer for example, when rendered on the search result page. However, this system has created confusion amog publishers and users finding it difficult to reach the content directly on a publishing site.
"An original publisher URL http://www.example.com/amp/doc.html, when a document is served Google AMP Cache, a URL is rewritten like; https://www-example-com.cdn.ampproject.org/c/www.example.com/amp/doc.html, and when it's displayed using Google AMP Viewer, the URL becomes: https://www.google.com/amp/www.example.com/amp.doc.html."
Google explains having these three URLs of different origins for essentially same content helps in "caching and pre-rendering" that contributes to AMP's spped. In the end, all Google URLs reflect the original source, because, a Google AMP URL, when shared outside of Google, redirect back to publishers site.
"When users scroll down the page to read a document, AMP viewer header bar hides, freeing up precious screen real-estate. And, when a Google AMP viewer URL is visited, where it's not available, the URL redirect to canonical page for the document," Google explained.
To make the system more transparent, Google adds an "anchor button" in the AMP Viewer header on Google Search, thus making it easier to access, copy and share canonical URL of a document "using the native share functionality of a browser by long-tapping on the link that is displayed." Next to the anchor button, the three dots called as "overflow" icon brings up help information about how AMP is displayed.
That said, Google Android app, will begin to share original URL, when a user tap on the share button, in the coming weeks. And for Google search app on iOS, this functionality is already available.
Google also said that they're working on to leverage to use web platform APIs such as Web Share API that would "allow AMP viewers to invoke the platform's native sharing flow with the original URL rather than the AMP viewer URL."