Page GUID as a discussion identifier
Page GUID is used as an identifier for discussions. In this case the page can be easily moved within site tree or mirrored, page name and URL can be changed. Disqus still can display corresponding discussion on a page using the same GUID and shortname.
Note that the same discussion is displayed for the specific CMS page even if you display different information depending on query string parameters. For example, it means that using Disqus comments on Relate website is sort of limited right now, but there is a plan to support this kind of scenario and Relate templates in the next version.
Discussion page URL
The system resolves the full external URL for each page that contain discussion. This URL is based on the site URL specified in EPiServer CMS Admin mode. Page URLs are available in several places in Disqus, like suggested links or URLs in comment notifications. Using full external URL we make sure that all visitors see links in the same format.
The title and the URL of the page become available in the number of places in Disqus as soon as comments were displayed on that page. Usually CMS editor is the first person who views the page before publishing. Page URL definitely should not be exposed on the public site until the page is published.
That’s why actual comments are displayed only on published pages in the view mode.
One shared dummy discussion is used to provide some kind of comments preview in Edit mode and on all unpublished pages. This discussion is named “Preview” and the site URL is used as URL for this discussion.
Issue indications on Edit UI
Only first comments block on the page is used to display discussion. All other occurrences are not rendered in view mode. However these “dead” blocks are indicated in Edit mode to provide some hints for editors.
Similar indication is used for comment blocks when Disqus is disabled on a website or shortname is not defined.