Archive for December, 2009

Eventually consistent world-view

Till sometime back, we used to build systems that were consistent at all times. When the user takes an action, all the data will be updated at all places synchronously. If any of the step fails, the entire transaction will be rolled back so that there was no inconsistency in the data.

That’s how it was till sometime back.

Then came a time when the data became geographically distributed, more data had to be manipulated per request, the data resided in multiple repositories and most importantly, the response time had to be reduced. This led to a new class of design where the data wasn’t always consistent. It was eventually consistent.

Eventual consistency of data meant that you could update part of the data now, and part of the data later and some part much later. The reason for doing this was simple, people demanded more real-timeliness; more than was possible by keeping data always consistent. In the new scheme of things, the application design will try to keep data always consistent for a specific user while at the aggregate level, it may not be. And more importantly, even for a user, a glitch once in a while has become OK.

The users today have become more tolerant to once-in-a-while glitches while the responsiveness rules.

Now, let’s look at media. Once upon a time, the journalists used to work very hard to come up with a consistent world-view that they could present to their readers. They’d verify the information from multiple sources to ensure that there were no holes in the story. Of course, it was a time-consuming process. It required work that had to be done before the news was broken.

But the very nature of news required speed in breaking the news. This speed requirement conflicted with the operating model of corroborating the information from multiple sources or verifying things to ensure that whatever was reported was always consistent with what actually happened. The competition forced media to take a route where the news would be broken as soon as it arrives and further verification would be done a little later.

That’s where things became interesting. Now, there was a shift in the model. The responsiveness of a media setup became more important than accuracy. You could be wrong once-in-a-while but you had to be first. Earlier, a witness would tell a journalist and a journalist would in turn verify and publish. But now, since the journalist would just publish and verification might happen later, the witness could just short-circuit the whole process and directly publish.

The first wave of this transition happened with blogs and twitter now rules the scene. It’s all because of responsiveness. It’s true that people can post false information also. But then the right information also trickles along. People may be misled for a while but they are fine with that. They eventually get to know the truth. The world-view with Twitter is eventually consistent. And that’s all that is required.

Media may be in the denial mode for now but they should understand it very well. They were the ones who invented eventual consistency of world-view to increase responsiveness. Or rather, the world-view of people has always been eventually-consistent, the current media setup was the first one to leverage it for increasing their responsiveness.

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