What exactly should <guid> contain?
Right now in my feeds I put there an URL to specific content. This should be unique identifier from my point of view, but is it right?
if you read the spec for the format of the feed you're using it'll probably explain better, but in short Marty-UK is right
for RSS at least (i'd have to check for Atom thou) <guid> is a sub-element of an <item>, preferably one <guid> for each <item>
the idea is to be a globally unique identifier, and thus the most important thing is that they never change
if you have "archives" which use permanent URLs then you can use the permanent URL as the GUID by specifying <guid isPermaLink="true">%URL to archive page here%</guid>
if you don't have archives, or for any other reason can't use a permanent URL, you can use and string as the GUID, but again, it must not change
to use a non-url guid, use... <guid isPermaLink="false">%string goes here%</guid>
considering they've got to be globally unique, but never changing, it might be an idea to use part of your domain name, or your own name prehaps
for example i use <guid isPermaLink="false">carre_##</guid> where ## is a number, which is handy to know how many items/entries i've posted, but it can be anything, and doesn't even need to use the same format for each item, they can be different lengths, and/or totally random strings, as long as they don't change, and are correctly labeled as permanent URLs or not
run your feed thru the FEED validator
to check that it's valid too (there's also a verson hosted by the W3C: W3C Feed validator
, it's the same code, (available from sourceforge.net) just incase the feedfalidator.org site is down (which happens sometimes)
something else that's handy is <pubDate>ISO date/time</pubDate> elements (the feed validtor will tell you if the format you use is correct, ISO dates have specific formats), so that feed readers know when an item was published (rather than a bunch of them all having the same date/time)
but like i said, read the specs, as they'll tell you exactly how things should be done...
RSS 2.0 Spec
- Atom Spec
for anyone who's interested in hosting a feed, for a blog, or news (or anything else) i strongly recommend the Atom format, it's much better than RSS, which is quite outdated these days, Atom is modern and solves many of the problems with RSS