I’ve been working on some feed support in MSDN’s new online platform (a beta of which is running http://msdn2.microsoft.com) and I had to decide what content-type to use when outputting a RSS feed. I knew this was a contentious issue in the past, but I thought it might have been resolved so I did some browsing of specs and discussions and ended up with the following links:
- A discussion on Sam Ruby’s blog around content-type (the comments are the interesting part)
- This post by Dave Winer
I’m sure I could find more, but it appears this was never really resolved… using application/xml seems the most ‘proper’, but the concern is that some browsers don’t know how to handle it … so the other choice is text/xml (specifically text/xml; charset=utf-8 or else the charset will default to US-ASCII). Hmm… which to choose? Even our own sites have multiple implementations:
- The main MSDN feed is application/xml
- while the [MSDN Magazine’s](http://msdn.microsoft.com/msdnmag/rss/rss.aspx?Sub=Service Station) (which is dynamically generated using ASP.NET) is output as text/xml; charset=utf-8
Interestingly enough, I found one feed that used application/rss+xml (Sam’s RSS 2.0 feed) which I think is probably not the best choice since that content type was never officially registered, and it was the only feed I hit that IE didn’t understand (and therefore tried to just download).
I think I will go with “application/xml” which has the best features in my opinion.
- It clearly indicates that this is not just text, so it should avoid issues with proxies messing with the characters,
- it leaves the character set data in the xml declaration, avoiding a possible conflict if I specify one in the http headers that is different than what the feed specifies,
- it displays correctly in IE and Firefox, and
- it is consistent with what we are doing today with the MSDN main feed.
Now, what about those in-page links we have?
<link rel="alternate" type="application/rss+xml" title="blah" href="rss.xml" /> …. perhaps they should be just “application/xml” as well?
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