Extensibility in Syndication formats

[Dare Obasanjo <kpako@xxxxxxxxx>]

--- Dan Brickley <danbri@xxxxxx> wrote:
>
> I'm comparing with RSS 1.0's
> RDF/XML-based
> extensibility framework; the other flavours don't
> really have one,
> except for RSS 2.0's "use namespaces and you're on
> your own".

I am suspicious of any claims that RDF buys you more
extensibility than using XML and namespaces in
practice. See
http://www.25hoursaday.com/weblog/PermaLink.aspx?guid=5b31837c-49cc-4d1d-9f14-fd25df8b54f2
for details. But let's go on... 
 
> The pre-IETF 
> Atom community decided some time ago that they
> didn't find RDF/XML 
> an attractive proposition, which I guess means we're
> going the route of 
> defining an extensibility model that is somehow
> better than RSS 1.0's.
> 
> Hmm so what were the key benefits of RDF
> extensibility in RSS 1.0? 
> 
>  - (fairly) predictable XML notation; RSS 1.0
> defined a profile of the 
>    RDF/XML syntax, so that namespace-extended feeds
> all shared a 
>    basic structure. (rather than allowing all RDF's
> syntactic
>    variations).

How is this practically useful? The fact that an
extension will show up as single elements with simple
content or as elements with attributes and complex
contents doesn't bring my application any closer to
understanding them when encountered in the wild. 

>  - Supported free combination of independently
> developed descriptive 
>    vocabulary (manifested as RDF/XML-based
> namespaces). RSS 1.0 feeds 
>    can carry extra markup describing things in the
> world beyond
>    syndication, such as people, places, movies, bank
> accounts. Element 
>    names in the markup correspond to classes
> (categories) and properties 
>    (fields, relations etc) defined by any RDF
> vocabulary that proves 
>    useful.

I see this in RSS 2.0 as well. 

>  - The external vocabularies a feed draws upon do
> not need to be defined 
>    with RSS 1.0 (or Atom or newsfeed syndication) in
> mind. Or be tightly 
>    coordinated amongst themselves. There is a
> tightly-defined model and 
>    simple-minded (additive) model for explaining how
> these independent 
>    namespaces interact when deployed together.

I see this in RSS 2.0 as well. 

> What were the problems / drawbacks with RSS 1.0's
> RDF extensibility?
> 
>  - explaining the XML-level constraints on markup
> structures amounted 
>    to the need to present a mini-tutorial on RDF's
> syntax rules, since 
>    RSS 1.0 used RDF's standard XML encoding.  This
> involves unenviable 
>    tasks like explaing RDF's "striped" XML style
> (see 
>    http://www.w3.org/2001/10/stripes/ ), and trying
> to summarise the 
>    rules for when you use "rdf:about=" versus
> "rdf:resource="
>    attributes.
> 
>  - when RSS 1.0 shipped (4 years ago) there weren't
> many RDF
>    vocabularies, software libraries were less
> mature, and the RDF
>    specs hadn't gone through the RDFCore cleanup
> (which finished Feb'04).
>    Sites like http://www.schemaweb.info/ show that
> there are a 
>    growing number of vocabularies, but many are
> still a bit drafty.
> 
>  - RSS 1.0 was perhaps a little too minimalist,
> forcing people to use 
>    extensions for things that a broader
> syndication-oriented vocab 
>    could have included in a more generous core.
> 
>  - The only widely used extension for carrying
> hypertext content in 
>    RSS 1.0 was 'content:encoded', which somewhat
> opts-out of 
>    the XML world. RDF in 2000 was a bit vague on how
> to deal with 
>    namespaces, xml:base, xml:lang  andther
> canonicalisation issues 
>    relating to "literal XML" content. (addressed in
> Feb'04 specs)
> 
>  - the blogging use case (which dominated RSS
> deployment and evangelism)
>    didn't have as much to gain from a powerful
> extensibility framework
>    as those apps which sometimes get called
> 'synthetic feeds'.

So far you have listed a bunch of drawbacks of the RDF
based approach used by RSS 1.0 and none of the
benefits that haven't been seen using just XML and
namespaces in RSS 2.0. 

=====
THINGS TO DO IF I BECOME AN EVIL OVERLORD #25
No matter how well it would perform, I will never construct any sort of machinery which is completely indestructible except for one small and virtually inaccessible vulnerable spot.


		
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