Is that going to change anytime? Would be such a great tool for publishing content if you could either publish to your own site, or control visibility on adobe's server. What are the plans?
You asked about an EPUB. Is your question about that or Publish Online?
PUBLISH ONLINE. I understand the published doc resides on the Adobe server. My question is about security of that document. Ideally I would embed the document on my website on a page only accessed by site members. But can the publication can be found on the Adobe server by anyone who might be browsing around?
You can't just browse the Adobe server. You would have to have the long alphanumeric string which is the URL to a particular document. But nothing would prevent someone with access to that URL from giving it to someone else.
If the embed code is used on my site, does that code contain the adobe server URL, and is that something that could be found by a site visitor?
I'm not really a web person. Don't know what an embed code actually contains. Someone else hopefully will reply.
… If the embed code is used on my site, does that code contain the adobe server URL, and is that something that could be found by a site visitor?
it's up to you how you implement the link with your website.
I found one example where a simple a tag is used:
The link to the published online "ScriptUi for Dummies" brochure for ExtendScript scripters at the bottom of the page could be identified easily by a human reader if looking at the website in code view. When in Firefox simply press: cmd u
<a href="https://indd.adobe.com/view/a0207571-ff5b-4bbf-a540-07079bd21d75">click here</a>
This link is meant to be found.
How to prevent readability of the URL ?
A very weak "security" approach:
Use an URL shortener like TinyURL.
Or by using dynamic content where a script is loading content at runtime.
Don't ask for specific hints, that's not my realm of expertise.