Have you ever interrupted an HTTP download and then restarted it later
and had it pick up where it left off? That little bit of magic is the
result of RFC3229: Delta encoding in HTTP. This is useful for more than just resuming downloads. Jon Udell, for example, uses this trick to access a small part of an MP3 file and its also the secret sauce in mod_speedyfeed that I mentioned yesterday.
This article by Bob Wyman that outlines the particulars.
In an interesting adaptation, while RFC3229 has always been about byte
ranges, but the mod_speedyfeed module uses RFC3229 with item ranges.
The bottom line: is there really isn't anything about this that would
keep it from working with RSS 2.0 as well as Atom.
We're keeping our eyes on any server-side
innovations that will limit resource consumption here at InfoWorld, so
we've got our eyes on this one, as we have for a while. Back in March,
Another interesting technical aside — as our RSS requests have grown
quickly, we have noticed increased server loads at the top of the hour
as aggregators “wake up” to pull feeds. Not a huge problem for us right
now, but the surge has roughly the same characteristics as a
distributed DoS attack and could eventually present trouble for really
huge web sites unless aggregators become a bit smarter.
I followed that up four months later noting that RSS was starting to hurt, and the community quickly rushed in with loads of good advice
that we heeded. It's nice to see that folks out there are continuing to
work to make both clients *and* servers smarter when it comes to RSS.
If there's anything InfoWorld can do to help test things like
mod_speedyfeed (within reason, of course — we do have a business to
run here), we are glad to pitch in.
Bonus link: story in the Seattle Times yesterday, “Software programs called RSS readers creating a blog jam.”
After speaking with Kim Peterson (the reporter doing the story), I
realized how difficult it is to explain RSS-related issues for a
general readership, so I don't envy her job. I think she did a good job
considering that the RSS concept is still a mental stretch for the
average person. I also hadn't heard of Findory until I read her piece, so I'm going to check it out.
I'm quoted calling RSS serving the “next-wave scaling problem,” but with folks like Garrett Rooney coding Apache modules like mod_speedyfeed just to “blow off steam,” I think we might beat that scaling issue before it becomes a nastier problem. [Chad Dickerson]