Too Busy For Words - the PaulWay Blog

Thu 27th Jan, 2011

Saying sorry and moving on

Today's keynote speech at LCA is from Eric Allman, the person who wrote 'sendmail', the main mail transfer agent that moves mail on the internet. There are many things in sendmail that have caused problems in the past, and its configuration syntax is known to cause brave men to wet themselves in fear. So I wanted to see how, or if, Eric would address these things in his talk.

Not only did he do this but he acknowledged the mistakes he had made. He talked about what he would do differently. He talked about the decisions he'd made that were forced by machine limitations, complete lack of standardisation of email address formats, and various other constraints. It's easy in hindsight to criticise some of these decisions but when you're starting out on a new system the horizon is wide open and you don't realise and sometimes can't even determine the scope of the consequences of your decisions.

Interestingly he pointed out the Postel principle - "be strict in what you emit and liberal in what you receive" as perhaps one of these mistakes. In his defence he said that there were many often completely incompatible email address formats and exchange methods, and professors get incredibly' irate when they find out that their grant application wasn't received. But it allows badly-written and incompletely-compatible systems to live and thrive, and I think we've seen this with HTML and other things - by Netscape allowing badly-written HTML to be rendered vaguely correctly it allowed IE to prosper.

But the thing I really appreciate is someone who will say "yeah, in hindsight that was a bad move". We all have reasons at the time, but there are a lot of bad decisions that are perpetuated - especially by large companies - because no-one is willing to admit that they made a mistake. It takes a lot of guts to stand up in front of eight hundred people who've all at one time or another struggled with sendmail and say "Yeah, M4, I don't think that was such a great idea". And yet it means we can now say "OK, well, let's get on with it anyway" and stop trying to blame sendmail for all our email problems.

His "takeaway" ideas were also really great and I think it validates Eric's experience as a programmer and system architect. The thing I would amplify from these was documentation: if you don't have documentation of your project, you'll never get any users.

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