Jon Udell: Paul Holbrook improves RSS truncation

Jon's Radio : Jon Udell's Radio Blog

Updated: 8/6/2002; 12:30:29 AM.

Note: Jon's Radio has moved to InfoWorld

Thursday, April 11, 2002

Paul Holbrook improves RSS truncation

Paul Holbrook takes a different approach to RSS truncation. He presents the entire lead paragraph, like so:

on firstPara(description, adrpost) {
return (html.getOneTagValue(description,"P"))}

The description is stored in HTML, so getOneTagValue conveniently does exactly what I want.

Of course, if the first tag in my description isn't a P, this won't do what I want it to do. I'll work on that another time. [ Paul Holbrook's Radio Weblog ]

I'm trying it now...yup, that's the ticket. Thanks, Paul!

7:50:36 PM

Now the RSS truncation is officially supported. I wish all collaboration were this easy. Explaining the new callback that makes my non-kosher hack into a kosher callback, Dave writes:

Actually Jon did a kosher thing. By documenting his hack and explaining the motivation clearly, and doing it slowly, he made sure that I understood what he was doing and why. I also could see that it wasn't a casual thing for him, he gave it a lot of thought. So now I can do a cow-path-pave for Jon and anyone else who may want more control over the descriptions in their RSS output feeds. [ Description Filter Callbacks ]

Thanks Dave! This posting is the first test...works! Cool.
5:08:05 PM

Shortening RSS descriptions to lead sentences

I'm really enjoying my ability to scan a lot of sources in my Radio news aggregator. What slows me down, though, are the channels with long or irregularly-formatted descriptions. One of the worst offenders is the Privacy Digest. I want to scan that channel, but the cluttered format of its descriptions makes it really hard to do so.

By contrast, take a look at Eric Snowdeal's feed. Although it's mildly disconcerting that the truncation doesn't respect word or sentence boundaries, the effect -- especially in the aggregator -- is to make this feed much more easily scannable.

For my own reading convenience, I may wind up pulling feeds out of Radio's aggregator database and reformatting them. But on the flip side, I've been feeling kind of antisocial about dumping these longish essays into an RSS feed that I myself wouldn't want to read.

So for now, I've changed this line in system.verbs.builtins.radio.weblog.writeRssFile:

add ("<description>" + adritemcache^.text + "</description>")

to this:

local (s = adritemcache^.text);
s = string.replaceAll( s, "<"   , "<" );
s = string.replaceAll( s, ">"   , ">" );
s = string.replaceAll( s, """ , '"' );
s = string.replaceAll( s, "'" , "'" );
s = string.replaceAll( s, "&nbsp;" , " " );
regex.subst("<[^>]+>", "", @s);
add ("<description>" + string.firstSentence(s) + "</description>")

Radio's string.firstSentence seems like just the ticket. A lead sentence is supposed to be special. Knowing that it's all a reader of your RSS feed might see (after the title) makes it even more so.

Of course, it's completely non-kosher to hack into a system script that can be overwritten by UserLand at any time, as happened most recently a few days ago:

4/7/02; 9:55:21 AM by DW {
Do the macro processing or descriptions unconditionally, and in-line instead of calling radio.string.processMacros, which was only processing the descriptions if it contained "<%". This broke shortcuts. Prior art is the Manila-Blogger Bridge Tool, which unconditionally processes macros.}

Nevertheless, you've got to love the openness of a system that makes it possible, and easy, to do this non-kosher thing.

2:16:56 AM