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Manifest(o)s, offline reading, and EPUB+WEB

From: Dave Cramer <dauwhe@gmail.com>
Date: Mon, 22 Jun 2015 14:54:32 -0400
Message-ID: <CADxXqOyvphxVzRVF7tT07A12ShBv8ZFS48sn5MN+oMdvJcTJDw@mail.gmail.com>
To: W3C Digital Publishing IG <public-digipub-ig@w3.org>
We've recently spent a lot of time discussing how to make a book [1]
readable both offline and online. As usual, this is an issue that has come
up in the larger web world. and there is a solution already supported by
every major browser. I'm speaking of AppCache [2], of course.

At first glance, AppCache seems well-suited for books. An application
manifest file (text-only) lists the resources used by the book, including
CSS, images, scripts, fonts, etc.:

CACHE MANIFEST
#v3 2015-06-05
css/mobydick.css
metadata.json
manifest.json
title-page.html
copyright.html
introduction.html
epigraph.html
c001.html
c002.html


When you first visit a page, the files listed in the manifest are
downloaded. The next time you visit the page, you'll get the cached
version. This is a problem for the regular web, but could be an advantage
for us. If you change the manifest file on the server, you will trigger an
update of the cache.

So my question is, why does everyone hate [3,sorry about the language]
this? The cache manifest itself would be helpful for EPUB+WEB, as it gives
us the list of files everyone seems to want, but far simpler than EPUB's
<manifest> element.

* * *

To be fair, the word "manifest" is probably less overloaded than the word
"template." Nevertheless, the "Manifest for a web application"
specification [4] appears to be unrelated to the application manifest used
by AppCache. Manifests for web applications are JSON files that provide
metadata for a web app. They could provide a location and syntax for book
metadata, and identify a starting point for the book:

{
  "name": "Moby-Dick",
  "short_name": "Moby-Dick",
  "icons": [{
        "src": "icons/moby-dick-icon.webp",
        "sizes": "64x64",
        "type": "image/webp"
      }],
  "start_url": "title-page.html",
  "display": "minimal-ui",
}

Together, these two manifests seem to meet several of EPUB+WEB's
requirements. I'm interested in further exploring these ideas to see if
they can be adopted or modified to meet our needs.

Dave


[1] Feel free to think "publication" every time I write "book" :)
[2] https://html.spec.whatwg.org/multipage/browsers.html#offline
[3] http://alistapart.com/article/application-cache-is-a-douchebag
[4] https://w3c.github.io/manifest/
Received on Monday, 22 June 2015 18:54:59 UTC

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