noted on Thu, 15 Jan 2004
WSMD as RSS/WSMD as Atom
The RSS implementation of WSMD
When I started writing this series of posts, I already had the properties of a WSMD file already in my head. Initial research suggested to me that RSS would be the only candidate, because the structure was simple enough, and I already understood it. So it came as a surprise to me to work this out and then realize that Atom and XHTML are also good candidates. Nevertheless, I’d like to demonstrate how these principles could be implemented in RSS.
The RSS implementation is dirt easy. I chose to work with the 0.91 spec so as to use a ‘lowest common denominator’. I’m going to assume that you already know how to read RSS files.
Let’s copy a list from this post. The properties of a WSMD entry must be:
- a URI to the asset
- an indication of what it is (possibly by mime-type, or a consistent use of terms)
- a description of what it is
Well, we got two of the three RSS tags used in each <item> nailed already — <link /> and <description />. So that leaves the title tag to hold the indication of what it is. That feels wrong to me, somehow, because it’s a <title /> tag, not <an-indication-of-what-it-is /> tag. Still, I guess it could be argued that a title is supposed to be an indication of what something is.
I’ve created the RSS implementation of the WSMD file. You can find the one for the home page here. I seem to have lost these files. I’ll look into recreating them at some future date.
What’s really cool about this minimal implementation is that if you want to add more metadata than the minimum I defined, you need merely switch to a more modern revision of RSS — one that supports, say, the Dublin Core metadata set, and run with that.
The Atom implementation of WSMD
Before I started this project, I knew about Atom, and ‘I was there’ when Sam Ruby first opened up the issue that eventually led to the fine work that has been done, and continues to be done, today. However, like many others, I was quickly overwhelmed by the frenetic pace of development, and decided to sit out until they had something to show for their efforts.
I sat down one weekend to look at the Atom Syndication Feed specification for the first time, and realized that this format was very interesting because it provided a richer markup framework for describing what a site was. A lot of this information wasn’t required, based on the model, but to provide it arguably leads to a higher-quality (and potentially more useful) description file.
Again, assuming you know how to mark up an Atom feed, consider the following:
Each entry in an Atom feed describes one asset of a web site. As in RSS, the <link />/<id /> tags point to the representation itself, the <summary /> tag will contain a human-readable description of the asset, and the title would contain the indication of what the resource is.
But the Atom syntax specs requires additional information in the feed. For example, each entry neds an <issued /> tag to indicate when the entry was, well, issued. Feeds also require at the top of the document such things as a title, a link to connect the feed to (in this case, it would be the home page of a site), a <modified /> tag to indicate the last modified date... you get the idea. There’s more information required to make up an Atom feed, much more than I think is required to describe a web site, but nevertheless, value is being added by filling in that data.
I have not at this time provided an atom version for your consumption, because in terms of structure, it is so similar to RSS that I believe nothing new could be learned by studying it in Atom.
Now let’s examine the XHTML version of a WSMD.