Channel Definition Format / rel=offline

[alnico]

I was testing the channel definition format (CDF) -- an obsolete xml technology that IE4 once used. The tag used to mark up CDF is

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<link rel="offline" href="example.cdf" />

Can HTMLValidator change the error message from

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The "rel" attribute contains an unrecognized value "offline". Make sure this value is correct.

to

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The rel="offline" value is an obsolete Channel Definition Format tag. Consider not using it

Thanks!
Nicholas

[MikeGale]

I remember CDF quite well. (It was developed, if I remember correctly, by a team based in Ireland with Europeans from several countries on board. I remember a presentation on it by a Norwegian working on the project.) It never took off and I was disappointed by the way it was launched as a commercial thing, we'll sell you a position...

Thanks for reminding me about it.

RSS, which I think is pretty analogous, was played better (though worse specified) and is now really widespread.

I'm not planning on going back to it, but I wonder if any browser still supports it. Anyone here know?

If it still works in some places, there's room to use it for some specialised purposes, like content that is deliberately limited to display on only some user agents.

[Albert Wiersch]

Thanks! In the next update, this warning message will be displayed:

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The "offline" value for the "rel" attribute is used for the obsolete Channel Definition Format (CDF), support for which has been removed from IE 7+ due to very limited use. Consider not using it.

According to Wikipedia, support for it was removed from IE 7, so I would suspect no modern (current) browser supports it.

[MikeGale]

Thanks Albert.

That's interesting. It's good to know that something is buried.

[alnico]

Thanks Albert, that should be good.

Mike, I can't find any literature as to why CDF was abandoned. It was free from patents, and I can't see why it didn't catch on whilst RSS did. Do you have any information why CDF flopped?

Thanks!
Nicholas

[MikeGale]

Hi Nicholas,

Unfortunately can't really help there.

I saw it before it was released and pictured, in my mind, usage which was pretty much the way RSS is used today. (I haven't looked for any notes I might have, but this was earlier than April 1998, so it was ahead of RSS.)

When it was released it came out as a prepopulated list which had been sold off to the highest bidder. You could still, presumably, use it as you wished but the default was this commercialised list.

I was dumbfounded by what had happened to a good idea. Unexpected to say the least.

I had been aiming to use it for my own purposes but the way it was presented turned me off. I never bothered. Maybe others felt the same!

Maybe the missing ingredient was a FeedReader style user agent.