Mon, 23 May 2022
RSS HACKS WITH XSLT

In my spare time I've been further tinkering (hopefully for the better) 
with my humble Shinobi Website[0] script. The most recent update in 
`patch-1` came with a solid amount of QoL improvements. If you're 
interested, I wrote about it on the official Shinobi blog[1].

The next feature I wanted to tackle was designing a custom layout for 
the XML files directly in the browser. I was greatly inspired to create 
something similar to Len Falken's main directory listing[2], since that 
blog was one of the original inspirations for Shinobi. I'm not able to 
copy what's there though, since our feed builds are quite a bit 
different.

I then proceeded to fall down the XSLT rabbit hole.


IT NEVER WORKS THE FIRST TIME, DOES IT?
---------------------------------------

Since the shinobi script generates valid RSS code by default, I didn't 
want to mess around _too_ much via XSLT and risk breaking validation. I 
also wanted to keep the "plain text" look-and-feel for consistency with 
the rest of the site, even though the XSLT template would render into 
standard HTML. Minor CSS styling and placing the content directly 
inside <pre> tags solved these issues.

My first attempt was to use the available `sort` parameter (in XSL 
version 1.1+) targeting the `dc:date` type linked to the <pubDate> 
element:

```xsl
<xsl:sort select="pubDate" data-type="dc:date" order="descending"/>
  <!-- each individual post's content here -->
```

This did not work as intended. RSS 2.0 requires that the <pubDate> 
content is set to comply with the RFC-822 date-time[3], which shinobi 
handles perfectly fine. The issue came from the XSL `sort` parameter 
not honoring this setting across all dates. My best guess is that it 
struggles to properly organize posts from their "month" parameter, so 
it sets the posts in order of date in what I refer to as "monthly 
sections".

If anyone knows why this failed to consistently order the posts via 
<pubDate>, please let me know using the comment link below. I'm far 
from an XSLT expert and might have overlooked something painfully 
obvious!


RSS HACK: CATEGORIES
--------------------

After spending far too much time reading over documentation, official 
manual pages and Stack Overflow comments I gave up on the `dc:date` 
sort. I realized I could sort the posts much easier if they were 
converted into a format similar to ISO 8601. But <pubDate> is required 
to be in RFC-822, so I couldn't alter that in the final XML file.

Then I remembered the <category> tag which shinobi does not utilize by 
default.

First I needed to convert the RFC-822 formatted date (found on the 
first line of all blog post text files) and render it inside a 
<category> tag. This was simple enough:

```shell
$(date -j -f "%a, %d %b %Y" "$(head -n 1 $file)" +"%Y/%m/%d/%u")
```

In a nutshell, this converts the RFC-822 date into the format 
"2022/05/24/2". Simple numbers that can be sorted much easier by XSL. 
Now all that was needed was setting to `sort` parameter properly:

```xsl
<xsl:sort select="category" order="descending"/>
```

Everything worked perfectly and the RSS was still valid!


PATCH-2 PENDING
---------------

I've ported these changes over to this blog to perform some "in the 
wild" testing. You can see the custom feed list in your supported 
browser by visiting:

https://tdarb.org/feeds/posts.xml

As for the shinobi project itself, I have not merged these updates into 
the main master branch (at the time of publishing this article). They 
can be found sitting on patch-2[4]. My plan is to get this merged ASAP 
once a little more real-world testing is finished and I can include a 
better "setup/install" section for newcomers.


SHINOBI UPDATES
---------------

If you're interested in more updates and details about the shinobi 
project itself, feel free to sub to that specific feed below. This post 
was more focused on hacking RSS parameters that happened to involve 
shinobi, but in the future all updates specific to the project will be 
posted there:

https://shinobi.website/feed.xml


COMMENTS
--------

https://lists.sr.ht/~tdarb/comments/%3C9DFCAEC4-816D-44F9-8DAC-93193F99F
CA3%40tdarb.org%3E


Thanks for reading,
-- Brad


LINKS
-----

[0]: https://shinobi.website/
[1]: https://shinobi.website/posts/patch-1.txt
[2]: http://len.falken.directory/
[3]: https://validator.w3.org/feed/docs/error/InvalidRFC2822Date.html
[4]: https://git.sr.ht/~tdarb/shinobi-script/tree/patch-2


* * *

Subscribe via RSS:
Posts > tdarb.org/feeds/posts.xml
Notes > tdarb.org/feeds/notes.xml

Help pay for hosting costs: 
https://www.nearlyfreespeech.net/contribute/tdarb.org (code: tdarb)

Maintained with love for the web. Member of https://1mb.club & 
https://xhtml.club

~ End of the page ~