A blog about software – researching it, developing it, and contemplating its future.

Archive for January 2008

Inside Stories and Posted Mortems

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Yikes, just missed my two-week window. Too much happening, too busy… get used to it, folks, it’s here for the duration, e.g. until this summer, after we’ve sold our house. Enough of that! Onwards!

Research papers are one of my biggest Internet weaknesses. Another one is post-mortems. If we learn from others’ mistakes, then post-mortems are solid education… they’re experience reports in their most tangible form.

For some reason, it seems there have been a whole slew of interesting ones on the net recently. Here they are:

  • Lambda the Ultimate cited this analysis of why Symbolics failed, as footnoted by Daniel Weinreb. Short story: too much technology, too little business focus. Still, interesting to get the inside view.
  • Even better are Daniel Weinreb’s posts about the history and impact of Object Design and Objectstore. Orthogonal persistence once seemed like a Really Good Idea to me, until we tried it at Electric Communities in the mid-nineties and couldn’t make it work. Even so, it looks like there are some valid use cases that Objectstore exploited about as well as possible. Did you know Amazon evidently relies on Objectstore caching for their entire inventory database?
  • Switching gears almost completely, from civilized discussion to rabid flaming, Zed’s infamous rant on leaving the Ruby community deserves mention. (WARNING: SOME NOT-SAFE-FOR-STRAITLACED-WORKPLACES CONTENT!) I have to admit I have a weakness for, shall we say, colorful language. The BileBlog (WARNING: DITTO!) was entertaining for a long time, though recently it’s gone dark… maybe Hani decided the career impact wasn’t worth the flameful fun. I’ve been tempted to go balls out and get explicit here, but the more I consider it, the less necessary it seems. Wait, that was all a huge digression away from the facts, which are that Zed’s rant is entertaining but I have no idea how accurate it is, and his comic self-promotion makes it hard to tell when he’s being serious and when he’s not, which hinders his message. He kind of wants to have his cake (“I’m so awesome, truly”) and eat it too (“Can’t you tell I’m mostly joking?”), which doesn’t do him any favors.
  • Meanwhile, the poor beleaguered Open Source Applications Foundation recently announced that Mitch Kapor is washing his hands of it all. No more funding on his nickel, almost two-thirds of staff laid off, and Katie Parlante left to try to turn it all into real revenue somehow. After six and a half years of Python hacking, they still barely have a usable application. Scott Rosenberg already told the whole epic story, but this seems like almost the last gasp. Open source projects can perish without clear architectural and requirements leadership, and OSAF will forever be the paradigmatic example. (I largely agree with, again, Dan Weinreb’s take on it all. I wonder if a good dose of RPython would help out Chandler at all?)
  • Finally, this isn’t new news (totally the opposite!), but I’ve got my own personal post-mortem skeleton in the closet, namely my involvement with the legendary Xanadu project. I’m quoted in the Wired post-mortem article. Some of what I said there was classic “this kid is young and bitter” uncensored vitriol. I’m glad that the brilliant people I worked with there understood that, because I want to work with some of them again some day! But overall, there is a lot of truth in that article, and it’s just a great read regardless. (Warning: that link is to the printer-friendly version, and Wired, under their new Conde Nast overlords, has lost their web-fu and has broken image links everywhere. Doesn’t matter; the text is all that counts in this instance.)

I’ve made some whopper mistakes in my career — some quite recently — and it’s too bad it will be a long time, if ever, before I get to tell the tales. (The downsides of modern tight-lipped corpocracy….) Still, we (hopefully) live and we (hopefully) learn. The more post-mortems, the better!


Written by robjellinghaus

2008/01/23 at 05:55

Posted in Uncategorized

GWT2007 Video, Brain Teasers, and Semantic Metatheory

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It’s almost terrifying how busy things are right now in robjsoftwareland. Moving with two young kids is just not the best idea from any kind of sane logistical perspective. Trust me on this. PLEASE. My life is a continual rolling boil of domestic packing and repacking and remodeling and general chaos, and it will continue for months to come.

But I cannot and will not go dark on this blog. So, a quick update:

1) The video from GWT2007 got posted! If my previous posts about my RPC talk made you curious, you can now see for yourself. I’m amused at the Sartre reference that snuck into the video 🙂 I think it came out quite well overall (with the caveat, as before, that an unexpectedly large portion of the audience were newbies who didn’t get the most out of it). The other talks are also online — now I’ll get to see the ones I missed! I’d also recommend Billy Hoffman’s talk on security (warning: one short NSFW item in there!).

2) I’m currently putting all research papers and language-y thinking on hold for a few months. Instead I’m getting back to basics. All my side reading/hacking time is going into plowing through these two books: Introduction to Algorithms and Artificial Intelligence: A Modern Approach. I’ve generally in the past spent most of my time reading current research, because books get out of date so quickly. Well, not these two! They come pretty darn close to being timeless.

One quick brain teaser from the algorithms book: Everyone knows how to write a recursive algorithm to print an inorder traversal of a binary tree. Almost everyone knows how to convert it to an iterative algorithm using an explicit stack, too. But the book mentions that — if your binary tree contains parent links as well as child links, and if you can test pointers for equality — you can actually write an iterative algorithm to do an inorder traversal without keeping an explicit stack… in other words, an iterative algorithm that uses constant space (rather than space proportional to the depth of the tree). It took me about twenty minutes to figure it out. How about you?

3) One of the more interesting posts recently on good old Lambda the Ultimate was this post by Paul Snively asking whether syntactic or semantic theory is the way of the future. Most approaches to programming language theory historically have been largely syntactic, but there are a number of recent papers that take a purely semantic view.

While I’m still learning this field myself (and haven’t spent nearly enough time on the basics — Pierce’s syntactically-oriented Types and Programming Languages is on my reading list, but so far I’ve only dabbled), it seems to me that semantic approaches have an intentional stance that might make them fundamentally more general. For example, this paper on semantic verification of a simple compiler makes the point that a typed assembly language program can only go wrong if it tries to treat a given memory location as being of an unsafe type, but that there might be possible values in that memory location which can be safely interpreted as other types without inconsistency.

This approach reminds me of the Logic of File Systems paper, in which file systems are modeled in terms of their beliefs about the contents of memory versus disk. It’s a fascinating philosophical view, to think of programs as enacted, operational beliefs and to consistency check them on that basis. A program only goes wrong if its beliefs are inconsistent with the contents of the machine, as opposed to being inconsistent with its own source text (represented as base terms of the program). It’s going to be fascinating to see how far the semantic approach can be pushed.

That’s it for early January — see you in about two weeks!

Written by robjellinghaus

2008/01/05 at 04:47

Posted in Uncategorized