ikiwiki/doc/todo/fancypodcast/discussion.mdwn

# Round 1

ikiwiki's simple podcasting, while elegant and minimal, doesn't (as
mentioned in [[todo/blogging]]) produce full-featured feeds. In
fancy podcasts, episodes are accompanied by text content. The feeds
also have lots more metadata.

## Design

7. For each fancy podcast episode, write a blog post containing
   `\[[!meta enclosure="WikiLink/to/media.mp3"]]`. (Don't specify
   more than one enclosure -- but if you do, last one wins.)
7. When rendering to HTML (single-page or inlined), append a link
   to the media file.
7. When rendering to RSS/Atom, the text is the entry's content and
   the media file is its enclosure.
7. Don't break simple podcasts in pursuit of fancy podcasts.

## Implementation

### Completed

* Cover the existing simple podcast behavior with tests.
* Add an `enclosure` field to [[plugins/meta]] that expands the
  given [[ikiwiki/WikiLink]] to an absolute URL (feed enclosures
  pretty much need to be, and the reference feeds I've looked at
  all do this).
* Write failing tests for the desired single-page and inlined
  HTML behavior, then make them pass by adding enclosure stanzas
  to `{,inline}page.tmpl`.
* Write failing tests for the desired RSS/Atom behavior, then make
  them pass via changes to `{atom,rss}item.tmpl` and [[plugins/inline]].
* Match feature-for-feature with
  [tru_podcast](http://www.rainskit.com/blog/542/tru_podcast-a-podcasting-plugin-for-textpattern)
  (what [[schmonz]] will be migrating from).
* Enrich [feed metadata](http://cyber.law.harvard.edu/rss/rss.html)
  by catching up `rsspage.tmpl` to `atompage.tmpl`.
* Verify that [[plugins/more]] plays well with fancy podcasts.
* Verify that the feeds validate.
* Subscribe to a fancy feed in some common podcatchers and verify
  display details against a reference podcast.
* Verify smooth transitions for two common use cases (see testing
  details below).
* Code review: don't add enclosure divs unless we have enclosures.
* Code review: genericize download link for more use cases.
* Code review: don't confuse old readers with Atom names in RSS.
* Code review: instead of hacking back to `$link`, just provide it.
* Code review: show author in addition to feedname, if different.

### Code review

	+                               # XXX better way to compute relative to srcdir?
	+                               my $file = $absurl;
	+                               $file =~ s|^$config{url}/||;

I don't think ikiwiki offers a better way to do that, because there is
normally no reason to do that. Why does it need an url of this form here?
--[[Joey]] 

> In all the popular, production-quality podcast feeds I've looked
> at, enclosure URLs are always absolute (even when they could be
> expressed concisely as relative). [Apple's
> example](http://www.apple.com/itunes/podcasts/specs.html#example)
> does too. So I told \[[!meta]] to call `urlto()` with the third
> parameter true, which means the \[[!inline]] code here gets an
> absolute URL in `$pagestate{$p}{meta}{enclosure}`. To compute the
> enclosure's metadata, though, we of course need it as a local path.
> I didn't see a less
> [ongepotchket](http://www.jewish-languages.org/jewish-english-lexicon/words/1402)
> way at the time. If you have a better idea, I'm happy to hear it;
> if not, I'll add an explanatory comment. --[[schmonz]]

>> I would be more comfortable with this if two two different forms of url
>> you need were both generated by calling urlto. It'd be fine to call
>> it more than once. --[[Joey]]

>>> Heh, it was even easier than that! (Hooray for tests.) Done.
>>> --[[schmonz]]

	+<TMPL_IF HTML5><section id="inlineenclosure"><TMPL_ELSE><div id="inlineenclosure"></TMPL_IF>
	+<TMPL_IF ENCLOSURE>

Can't we avoid adding this div when there's no enclosure? --[[Joey]]

> Sure, I've moved the `<TMPL_IF ENCLOSURE>` check to outside the
> section-and-div block for `{,inline}page.tmpl`. --[[schmonz]]

	+<a href="<TMPL_VAR ENCLOSURE>">Download this episode</a>

"Download this episode" is pretty specific to particular use cases.
Can this be made more generic, perhaps just "Download"? --[[Joey]] 

> Yep, I got a little carried away. Done. --[[schmonz]]

	-<TMPL_IF AUTHOR>
	-       <title><TMPL_VAR AUTHOR ESCAPE=HTML>: <TMPL_VAR TITLE></title>
	-       <dcterms:creator><TMPL_VAR AUTHOR ESCAPE=HTML></dcterms:creator>

This change removes the author name from the title of the rss feed, which
does not seem necessary for fancy podcasts. And it is a change that
could negatively impact eg, Planet style aggregators using ikiwiki. --[[Joey]]

> While comparing how feeds render in podcatchers, I noticed that
> RSS and Atom were inconsistent in a couple ways, of which this was
> one. The way I noticed it: with RSS, valuable title space was being
> spent to display the author. I figured Atom's display was the one
> worth matching. You're right, of course, that planets using the
> default template and somehow relying on the current author-in-the-title
> rendering for RSS feeds (but not Atom feeds!) would be broken by
> this change. I'm having trouble imagining exactly what would break,
> though, since guids and timestamps are unaffected. Would it suffice
> to provide a note in the changelog warning people to be careful
> upgrading their planets, and to customize `rssitem.tmpl` if they
> really prefer the old behavior (or don't want to take any chances)?
> --[[schmonz]]

>> A specific example I know of is updo.debian.net, when used with
>> rss2email. Without the author name there, one cannot see who posted
>> an item. It's worth noting that planet.debian.org does the same thing
>> with its rss feed. (That's probably what I copied.) Atom feeds may
>> not have this problem, don't know. --[[Joey]]

>>> Okay, that's easy to reproduce. It looks like this _might_ be
>>> a simple matter of getting \[[!aggregate]] to populate author in
>>> `add_page()`. I'll see what I can figure out. --[[schmonz]]

>>>> Yep, that was mostly it. If the feed entry defines an author,
>>>> and the author is distinct from the feed name, we now show `NAME:
>>>> AUTHOR`, else just show `NAME` (same as always). In addition,
>>>> the W3 feed validator says `<dcterms:creator>` is invalid, so
>>>> I replaced it with `<dc:creator>`, and all of a sudden `r2e`
>>>> gives me better `From:` headers. With the latest on my branch,
>>>> when I generate the same planet as updo and run `r2e` over it,
>>>> the names I get in `From:` look like so:

*  `"updo: Junio C Hamano"`
*  `"updo: Greg Kroah-Hartman"`
*  `"updo: Eric Raymond: esr"` (article author != feed name, so we get both)
*  `"updo: Jannis Pohlman: Jannis Pohlmann"` (oops! I tweaked the real updo)

>>>> --[[schmonz]]

	+++ b/templates/rsspage.tmpl
	+	xmlns:atom="http://www.w3.org/2005/Atom"
	+<atom:link href="<TMPL_VAR FEEDURL>" rel="self" type="application/rss+xml" />

Why is it using atom namespace inside an rss feed? What are the chances
every crummy rss reader on earth is going to understand this? I'd put it at
about 0%; I doubt ikiwiki's own rss reader understands such a mashup.
--[[Joey]]

> The validator I used (<http://validator.w3.org/feed/>) told me to.
> Pretty sure it doesn't make anything work better in the podcatchers
> I tried. Hadn't considered that it might break some readers.
> Removed. --[[schmonz]]

	+<generator>ikiwiki</generator>

Does this added tag provide any benefits? --[[Joey]]

> Consistency with the Atom feed, and of course it trumpets ikiwiki
> to software and/or curious humans who inspect their feeds. The tag
> arrived only in RSS 2.0, but that's already the version we're
> claiming to be, and it's over a decade old. Seems much less risky
> than the atom namespace bits. --[[schmonz]]

>> Sounds ok then. --[[Joey]]