September 05, 2007 By Christopher Bucchere

Web 2.0 and Cascading SLAs


twitter-down-againHerein lies a great example of one of the downsides of Web 2.0. It's something I call "cascading SLAs."

I was checking feedhaus today and I noticed that the flickr badge (the cool lil' widget that displays a little collage of photos) was down for the count. I thought perhaps I had broken something on the dev server, but a quick health check revealed that everything was okay with feedhaus.

So, I decided to check out flickr to see if there were any messages about known downtime, current server issues, etc. Lo and behold, flickr was also down! Hello? Anyone? Bueller?

This demonstrates one of the classic problems with mashups, a crucial component of Web 2.0: cascading SLAs (Service-Level Agreements), or, more precisely, a lack thereof.

Here at feedhaus, I have a responsibility to provide up-to-date news so that my users will be the "first to know." I can (although I probably won't) guarantee a level of service for feedhaus's ability to deliver content. But, as a multi-band content aggregator, I'm solely dependent on the sources of content -- namely flickr, YouTube and you-name-it syndicated feed from Now if my sources are CNN, Google, Fox, etc. I would expect pretty dependable service. But Digg? Twitter? Seeing what happened to Skype recently, I'm beginning to wonder if everyone, even the biggest -- and most distributed -- systems are subject to serious unplanned downtime.

So, what I'm getting at here is that my SLA, no matter how much I pay my attorneys to draft it, is only as good as the SLAs of the services that I use. Now, I'm not paying the sources for those services -- and, I might add, you're not paying me to use feedhaus -- so I have no SLAs for my underlying services, which makes my SLA worth less than the paper it's printed on. Do you see the problem? (I'm reminded of a certain scene from the 1989 classic comedy Major League. "See, it says right there; no calisthenics. What do you think of that?")

So, before you start drafting that SLA for the cool new mashup you just built between Google Maps and Facebook, think about the stability and sustainability of your sources. Or else your SLA might have the same fate as Roger Dorn's contract. . . .

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