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Mon, 20 Mar 2006

Blosxom sucks
Several people were upset at my recent discussion of Blosxom. Specifically, I said that it sucked. Strange to say, I meant this primarily as a compliment. I am going to explain myself here.

Before I start, I want to set your expectations appropriately. Bill James tells a story about how he answered the question "What is Sparky Anderson's strongest point as a [baseball team] manager?" with "His won-lost record". James was surprised to discover that when people read this with the preconceived idea that he disliked Anderson's management, they took "his record" as a disparagement, when he meant it as a compliment.

I hope that doesn't happen here. This article is a long compliment to Blosxom. It contains no disparagement of Blosxom whatsoever. I have technical criticisms of Blosxom; I left them out of this article to avoid confusion. So if I seem at any point to be saying something negative about Blosxom, please read it again, because that's not the way I meant it.

As I said in the original article, I made some effort to seek out the smallest, simplest, lightest-weight blogging software I could. I found Blosxom. It far surpassed my expectations. The manual is about three pages long. It was completely trivial to set up. Before I started looking, I hypothesized that someone must have written blog software where all you do is drop a text file in a directory somewhere and it magically shows up on the blog. That was exactly what Blosxom turned out to be. When I said it was a smashing success, I was not being sarcastic. It was a smashing success.

The success doesn't end there. As I anticipated, I wasn't satisfied for long with Blosxom's basic feature set. Its plugin interface let me add several features without tinkering with the base code. Most of these have to do with generating a staging area where I could view posts before they were generally available to the rest of the world. The first of these simply suppressed all articles whose filenames contained test. This required about six lines of code, and took about fifteen minutes to implement, most of which was time spent reading the plugin manual. My instance of Blosxom is now running nine plugins, of which I wrote eight; the ninth generates the atom-format syndication file.

The success of Blosxom continued. As I anticipated, I eventually reached a point at which the plugin interface was insufficient for what I wanted, and I had to start hacking on the base code. The base code is under 300 lines. Hacking on something that small is easy and rewarding.

I fully expect that the success of Blosxom will continue. Back in January, when I set it up, I foresaw that I would start with the basic features, that later I would need to write some plugins, and still later I would need to start hacking on the core. I also foresaw that the next stage would be that I would need to throw the whole thing away and rewrite it from scratch to work the way I wanted to. I'm almost at that final stage. And when I get there, I won't have to throw away my plugins. Blosxom is so small and simple that I'll be able to write a Blosxom-compatible replacement for Blosxom. Even in death, the glory of Blosxom will live on.

So what did I mean by saying that Blosxom sucks? I will explain.

Following Richard Gabriel, I think there are essentially two ways to do a software design:

  1. You can try to do the Right Thing, where the Right Thing is very complex, subtle, and feature-complete.
  2. You can take the "Worse-is-Better" approach, and try to cover most of the main features, more or less, while keeping the implementation as simple as possible.
Doing the Right Thing is very difficult. If you get it right, the resulting system is still complex and subtle. It takes a long time to learn to use it, and when users do learn to use it, it continues to surprise and baffle them because it is so complex and subtle. The Right Thing may contain implementation errors, and if it does the user is unlikely to be able to repair them without great effort.

Worse, because the Right Thing is very difficult to achieve, and very complex and subtle, it is rarely achieved. Instead, you get a complex and subtle system that is complexly and subtly screwed up. Often, the designer shoots for something complex, subtle, and correct, and instead ends up with a big pile of crap. I could cite examples here, but I think I've offended enough people for one day.

In contrast, with the "Worse-is-Better" approach, you do not try to do the Right Thing. You try to do the Good Enough Thing. You bang out something short and simple that seems like it might do the job, run it up the flagpole, and see if it flies. If not, you bang on it some more.

Whereas the Right Thing approach is hard to get correct, the Worse-is-Better approach is impossible to get correct. But it is very often a win, because it is much easier to achieve "good enough" than it is to achieve the Right Thing. You expend less effort in doing so, and the resulting system is often simple and easy to manage.

If you screw up with the Worse-is-Better approach, the end user might be able to fix the problem, because the system you have built is small and simple. It is hard to screw it up so badly that you end with nothing but a pile of crap. But even if you do, it will be a much smaller pile of crap than if you had tried to construct the Right Thing. I would very much prefer to clean up a small pile of crap than a big one.

Richard Gabriel isn't sure whether Worse-is-Better is better or worse than The Right Thing. As a philosophical question, I'm not sure either. But when I write software, I nearly always go for Worse is Better, for the usual reasons, which you might infer from the preceding discussion. And when I go looking for other people's software, I look for Worse is Better, because so very few people can carry out the Right Thing, and when they try, they usually end up with a big pile of crap.

When I went looking for blog software back in January, I was conscious that I was looking for the Worse-is-Better software to an even greater degree than usual. In addition to all the reasons I have given above, I was acutely conscious of the fact that I didn't really know what I wanted the software to do. And if you don't know what you want, the Right Thing is the Wrong Thing, because you are not going to understand why it is the Right Thing. You need some experience to see the point of all the complexity and subtlety of the Right Thing, and that was experience I knew I did not have. If you are as ignorant as I was, your best bet is to get some experience with the simplest possible thing, and re-evaluate your requirements later on.

When I found Blosxom, I was delighted, because it seemed clear to me that it was Worse-is-Better through and through. And my experience has confirmed that. Blosxom is a triumph of Worse-is-Better. I think it could serve as a textbook example.

Here is an example of a way in which Blosxom subscribes to the Worse-is-Better philosophy. A program that handles plugins seems to need some way to let the plugins negotiate amongst themselves about which ones will run and in what order. Consider Blosxom's filter callback. What if one plugin wants to force Blosxom to run its filter callback before the other plugins'? What if one plugin wants to stop all the subsequent plugins from applying their filters? What if one plugin filters out an article, but a later plugin wants to rescue it from the trash heap? All these are interesting and complex questions. The Apache module interface is an interesting and complex answer to some of these questions, an attempt to do The Right Thing. (A largely successful attempt, I should add.)

Faced with these interesting and complex questions, Blosxom sticks its head in the sand, and I say that without any intent to disparage Blosxom. The Blosxom answer is:

  • Plugins run in alphabetic order.
  • Each one gets its crack at a data structure that contains the articles.
  • When all the plugins have run, Blosxom displays whatever's left in the data structure.
End of explanation; total time elapsed, three seconds. So OK, a plugin named "AARDVARK" can filter out all the articles and nobody else gets a chance to look at them. So what? That is a feature, not a bug. It's simple. It's flexible enough: If you don't like that "AARDVARK" runs first, rename it to "zyzzyva"; Problem solved. An alternative design would be to have a plugin registry file that lists the order in which the plugins will be run. In the right system, that could be the Right Thing. In a system as simple as Blosxom, it would have been the wrong thing, not Worse-is-Better, but just Worse. The author knew just exactly how much design was required to solve the problem, and then he stopped.

So Blosxom is a masterpiece of Worse-is-Better. I am a Worse-is-Better kind of guy anyway, and Worse-is-Better was exactly what I was looking for in this case, so I was very pleased with Blosxom, and I still am. I got more and better Worse-is-Better for my software dollar than usual.

When I stuck a "BLOSXOM SUX" icon on my blog pages, I was trying to express (in 80×15 pixels) my evaluation of Blosxom as a tremendously successful Worse-is-Better design. Because it might be the Wrong Thing instead of the Right Thing, but it was the Right Wrong Thing, and I'd sure rather have the Right Wrong Thing than the Wrong Right Thing.

And when I said that "Blosxom really sucks... in the best possible way", that's what I meant. In a world full of bloated, grossly over-featurized software that still doesn't do quite what you want, Blosxom is a spectacular counterexample. It's a slim, compact piece of software that doesn't do quite what you want---but because it is slim and compact, you can scratch your head over it for couple of minutes, take out the hammer and tongs, and get it adjusted the way you want.

Thanks, Rael. I think you did a hell of a job. I am truly sorry that was not clear from my earlier article.


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