12 entries tagged rss

RSS 0.91 experiments

I have created an experimental RSS feed (‘channel’) for this site. In principle this can be used by people with RSS aggregators to mix my latest headlines in with other channels.

The documentation for RSS I am using is Dave Winer’s, because he is one of the few people to actually document it. Erm, except that I have taken the liberty of adding an XML namespace attribute (using the namespace mentioned in an article about RSS 1.0).

I am using the description field to hold (part of) the first paragraph, by way of a teaser; readers are expected to follow the link to read the thing in full. I was a little surprised to discover that RSS 0.91 has no provision for supplying a date for news items. For weblog-style channels, this seems like a major omission!

I also really dislike the RSS-0.91 de-facto convention of using escaped HTML text as the value of titles and descriptions. For one thing, why not just embed HTML as-is instead of under an extra layer of encoding? (That’s the whole point of XML namespaces, for example...) Worse, many people just grab the first 100, say, characters, regardless of whether decoding the result will be valid HTML or not! This means that you cannot safely use XSLT to transform RSS 0.91 to HTML, unless I am missing something... Anyway, in my feed I am making a point of stripping out all mark-up before adding to the RSS file. People who want to see it formatted will have to follow the link!

Two silly suggestions for RSS 2.0

I’ve been thinking about the various RSS branches and the RSS-2.0 process and send this to Mark Pilgrim and Dave Winer. Since then I have been sort out a draft recommendation. It’s tricker than I thought...

Version numbers in namespaces considered harmful

The various flavours of RSS offer a variety of namespace requirements:

URL RSS version
http://my.netscape.com/rdf/simple/0.9/ 0.9
(default) 0.91, 0.92, 0.94
http://purl.org/rss/1.0/
http://purl.org/rss/1.0/modules/rss091# 		1.0
http://backend.userland.com/rss2 2.0

In my opinion, it is a grave mistake to include a version number in a namespace URI. The function of a namespace is to prevent accidental collisions between names defined by different people (or organizations) when two XML vocabularies are combined in one document. The version number of the format can be specified separately (as indeed all the RSS versions do, as an attribute of their root element). If the 0.9 spec had only used http://netscape.com/1999/rss as its namespace (following the lead of http://www.w3.org/1999/xhtml) then all the versions could have used the same namespace.

Why do I care, you ask? Because if you use actual XML tools like XSLT to manipulate RSS feeds, then the fact that there are three or four namespaces in use for essentially the same elements makes the whole thing more complicated. Where I might have had 

<xsl:template match="/rss:rss/rss:channel">...

I better be prepared for more complicated expressions like 

<xsl:template match="/*/*[lname()=channel]">...

(to allow for any root element, and to ignore the namespace of the channel element). This clutters the XSLT file and makes it harder to maintain—and probably also less efficient. Sigh.

This is not unique to RSS, by the way—I had all sorts of hassle with early ve4sions of SVG tools which were caught out by the ever-changing SVG namespace URL. They finally settled on the quite-sane http://www.w3.org/2000/svg.

Namespaces annoyances in RSS

In an earlier note I listed four namespaces used in RSS and RSS for the same element names. One of these has now been unmade: the RSS specification never explicitly mentioned the namespace, but the sample file included an xmlns attribute. While I was away in Canada, this was removed to ensure backward compatibility with RSS 0.91. This makes sense (there exist examples of applications that genuinely are broken by this), but is kind of icky.

There is still the old RSS 0.9 format—which did use its own namespace—but given that even RSS 1.0 did not preserve that, I think we can assume it is dead too. I assume that the programs that were broken by the fleeting addition of the RSS-2.0 namespace are also incapable of parsing RSS-1.0 data?

I just tried printing a copy of the RSS 2.0 spec., but because he chose to use a fixed-width table for the text, it is clipped all down the right-hand side of the page, making it useless. Goddammit!

Update (2002-10-14): I have removed the namespace declaration from my experimental RSS feed.

XSS—Extremely Simple Syndication

Proposal for Extremely Simple Syndication (XSS), a profile (a restricted subset) of RSS 2.0, proposed by Tim Appnel (tima) [pointer from Mark Pilgrim]. This is the same acronym as I timidly suggested for the successor to RSS 0.92. I had started on something I was going to call XSS myself, but tima’s is headed in the same direction, so I should probably just withdraw my inchoate drafts to prevent any confusion...

I had started drafting a proposal myself, but in the end I don’t have time to do it properly (my evenings at home should be spent on the CAPTION web-site...). Oh, well. Excuses, excuses.

On the subject of things I don’t have time to do: Lars Marius Garshol points to a treatment of RSS data in AsTMa=. (AsTMa= is a linear notation for Topic Maps). I would like to do a proper treatment of interoperable syndication data in topic-map format, but, again, no time...

Dave Whiner asks that people not use variations on the white-on-orange XML icon (used to link to RSS data). So I have changed the link on my pages to use the ‘standard’ image.

RSS valid, again (ahem)

My RSS 0.9x feed failed to validate after my last entry—because I included an HTML 4 character entity in the title. (I used &mdash; to create an em-dash.) This is OK for HTML, but forbidden in RSS. I have fixed the script that generates the file so it converts these entities in to the corresponding Unicode character. Sorry for any inconvenience.

LifeJournal syndication

Jo Charman has created a LiveJournal ‘syndication account’ for me. As a result you can see my RSS feed, converted in to a LiveJournal journal. She says that if you have a paid-for LiveJournal account, you can add pdc to your friends roster. And people can comment on the LiveJournal pointers to my posts. Woohoo.

Updated (4 March 2007). Updated URL. Corrected the spelling of Jo’s first name.

RSS changes

Up until today my RSS feed has had one link per day, even though there might be extra (supplementary) articles on that day. If you look at the HTML page, the first article of the day gets the big heading with the date and suchlike, and the subsequent articlettes get smaller headings. Up until now the smaller articles were omitted from the RSS.

I have now tweaked the program that generates it so that these smaller headings also get links in the RSS data. At the moment they link to their parent item; this will change once I add HTML anchors to the headings so that they can link direct to those. Sorry for any inconvenience.

RSS feed broken today, sorry

Last night I hacked the code that generates the archive web pages for my weblog (or whatever it is this site is) so that the headings of the supplementary articles also have link anchors. In the process I broke my RSS feed slightly—it got confused by the id tags. (while remaining technically valid according to the RSS validator). This has now been fixed, so that (a) all articles have an HTML link target and (b) all articles are linked to from the RSS feed.

Small objects of desire

I’have had a Palm 3 for some time (creaky old 2-MB model). I used to say that when I upgraded it, I wanted that to be next upgrade for my phone, as well. That product now exists in the form of the Handspring Treo, a compact palmtop with a phone built in, and Jo has one. Sadly Handspring don’t consider Grafitti an asset in a device aimed at non-Palm-users, so the 180g has already been air-brushed out of history in favour of its keyboard-sporting cousin. The problem is the Treo does cost rather a lot more than, say, Adrian’s entry-level Sony Clié, which is similarly compact and has a high-res screen. I really don’t know which I would prefer as the successor to my clunky old Palm 3.

Actually the fact is I don’t need to replace my disfunctional old Palm 3; I frankly don’t use very much, not the way Jo and Jeremy use theirs. Its main failing is not its memory size but its size—justa little bit bigger than pocket sized (unlike both the Clié and the Treo). I have admitedly upgraded my Alcatel Max DB phone (the same model that caused mpt so much confusion) for its smaller successor the 311, but that is still one of Virgin’s cheapest handsets and I only rarely use the thing. I have absolutely no need to upgrade either of them. Annoyingly.