Javascript is strongly discouraged in OPS 2.0 (Bookworm disallows it altogether), so I don’t think that’s a great loss. Allowing it at all is just asking for malware.

Personally, I have zero interest in a standalone ePub reader that is disconnected from the net as a whole, so I don’t have a horse in this particular race.

That’s what Digital Editions is.

Not correct.

Adobe’s AIR uses Webkit for rendering HTML and CSS. Digital Editions for rendering HTML and CSS uses some browser engine which is neither Webkit nor Gecko, but which supports Adobe’s XML language used for laying out pages. This engine also comes without support for Javascript, so – no prospect for any scripting inside pages.

Though, of course, approach of Digital Editions is quite similar to approach of Adobe’s AIR: both embed HTML and CSS rendering engine into Flash wrapper.

Yet another solution would be to develop EPub reader on top of Adobe AIR platform.

That’s what Digital Editions is.

Titanium, although only in preview releases as yet, seems to be more promissing than Adobe’s AIR since it

1) does not demand specific runtime preinstalled,
2) fully open source,
3) supports many languages, e.g Python, Ruby.

Titanium apps can also read ZIP files using modules of third party programming languages be it Ruby, Python or PHP.

I agree that Flash and Silverlight are undesirable for many reasons, but they’re portable (like JS) and can read ZIP files (unlike JS).

OpenBerg Reader can read ZIP files. ZIP files can also be read by the new versions of Opera browser (not officially released as yet; should be downloaded from Opera Labs).

I’m just as not-fond of browser plugins, though.

Of course, it would be better to have Epub reader not as a browser plugin but as some standalone program. A possible solution here would be release of stripped Firefox browser (renamed, of course) with Epub reader extension preinstalled. Another possible solution would be to develop Epub reader on top of Mozilla’s XULRunner platform. That would solve extension downloading and installation hassles.

Yet another solution would be to develop EPub reader on top of Adobe AIR platform. AIR supports ActionScript 3 which can read ZIP files. Such reader would be not standalone since it would require AIR runtime environment.

I’ve got something in the pipeline that is pure JavaScript, although it won’t solve every one of these issues and I’m not sure yet when it will be ready for prime time.

Javascript isn’t a kind of self-sufficient platform. Javascript would need some environment to be run and HTML and CSS would need some rendering engine. How would pass together these parts of Epub reader in your solution?

I’m just as not-fond of browser plugins, though. Inspired by these comments I’ve got something in the pipeline that is pure JavaScript, although it won’t solve every one of these issues and I’m not sure yet when it will be ready for prime time.

Provide a lightweight, open-source widget that can render an ebook in a browser, similar to the BookGlutton reader. Authors could use this to distribute long-form works easily.

I think this is a fantastic idea. Before I developed Bookworm I looked around for a JavaScript ZIP library but went the server-side route instead. I suspect such a widget would have to be in Flash or Silverlight, though, unfortunately.

I think that relying on Flash or Silverlight would be wrong for such a project. Neither Flash nor Silverlight can render HTML and CSS; but poor rendering of HTML and CSS is one of the main drawbacks of current Epub readers such as FBReader or Stanza.

A reader as an extension for some cross-platform browser seems to be much better solution. There are already two such projects: OpenBerg Reader extension for Firefox and EPub Reader extension for Opera. Unfortunately, the first seems to be dead (no version for Forefox 3 released) and the second immature and not being actively developed.

If someone would revive OpenBerg project or would push Opera’s Ebook Reader project until into maturity – that would be really fantastic!