I know several of this blog’s readers use subversion (I tend(ed?) to recommend subversion recently). I hope this post may save you a couple of frustrating hours hunting for a vague data corruption problem.

Yesterday I wanted to add some images to my website, from a computer I don’t normaly work on. Therefore I made a fresh checkout. Before completing the checkout, subversion exited with:

svn: Checksum mismatch on rep '1v6': 

and the two checksums that might be off. I finally found the solution for subversion checksum mismatch in the subversion users mailing list.

Several other workarounds suggested removing the offending directory and trying update, but that didn’t work (not even on a working copy). If you follow the instructions , you may be left wondering how to find the checksum in the representations.dump file as I was. I tried searching for the checksum, but that didn’t go so well.

The ‘1v6’ from my error message indicates a node number or something. There’s only one in the file. And, as instructions” say, you really do need 16 repeats of \00, like so:

1v6
 ((fulltext 1 2 (md5 16 \00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00)) 3 1v6)

I tried replacing it with the same amount of slashes as were there in the first place, but that didn’t work.

For future reference, I had this problem with svn, version 1.2.0 (r14790) on windows and reproduced it on debian linux, and still had the problem with version 1.2.3 (r15833).

I like subversion for all its’ features, but in moments like this, I guess I’d prefer a version control system that uses the filesystem as-is. Probably my repository has been corrupted since revision 2 (out of 130 revisions…) as svn dump stopped when dumping this revision. Apparently, I’m using this repository write-only, and subversion doesn’t see anything wrong when one one only perfomrs commits.

In case you wonder, the file in question was fine, it was only the checksum in the database that was corrupted…

I’m running around this week, so just a quick update on events I’m involved in.

XP Days London have accepted Temperature Reading. That means I’ll go on tour again in November, to XP days Benelux, then Germany and finally London .

The Software Practice Advancement Conference has accepted These are just some of my favourite tools and Balancing Act – Simple tools for Feedback, Courage and Communication

I’m co-sponsoring the next agile seminar , which will be held in Nieuwegein on October 26th. We’re having an interactive session on the Toyota way and a talk on agile outsourcing, and of course… drinks.

On October 27, 28 and 31 Rob Westgeest and yours truly are organising the fourth eXperience Agile training here in Eindhoven. We have a few places left, contact me if you’d like to participate.

I’m trying to freewrite, creating an environment where I can’t be disturbed. I used my alarm clock from the kitchen – the alarm chicken. Only, just before I got started, I was disturbed by its’ noise, since it is a mechanical clock that keeps ticking.

Last weekend, and Monday and Tuesday I spent at European Consultants’ camp in Berdorf, Luxembourg.

The freewriting workshop hosted by Laurent Bossavit was one of the highlights in four days filled with highlights. I’m not sure any written description can do justice to the friendly, familiar, sometimes puzzling often hilarious and challenging company I found myself in.

During the freewriting workshops for instance, I spent seven minutes on a task (or constraint) set by someone else. I had to write a fantasy story. After laughs about the multiple meanings of fantasy, I set myself to writing a story about a hobbit.

This was the first time since (I had to in) high school that I wrote a fiction story. I found it actually quite fun. Besides having to continue writing leads to funny sentences sometimes, as appeared in the story.

While writing the first sentence I found I had to have a name for my hobbit, but couldn’t find one, so instead I decided to make the hobbit so drunk he couldn’t remember his name.

I hope that showed something about how freewriting can help to free creative juices.

One more thing I find with freewriting is that even with a few simple, generative rules you can play.

One of the rules said that you have to write without stopping. How to play with that one? Simple: write slower, so you have time to think more.

Actually, I had to write slower, because I got cramped, which seems to be a common experience when you don’t practice freewriting much.

The chicken has just rang, I now notice I was so absorbed in writing that I didn’t notice the ticking anymore.

Laurent will also host a lightning writing workshop at xp days Benelux which I heartily recommend if you want to write more often and with more fun.

(asides from a few minor edits, this blog entry was freewritten in ten minutes plus a bit, with pen and paper, with a few minor spelling edits afterwards).

Nat Pryce wrote me about the previous entry:

I just read your blog post about the review processes for XP Day Benelux and London. I just want to assure you that all submissions will get feedback. If the review process doesn’t provide feedback to some sessions the programme committee members will write three (or more) reviews for those sessions before deciding the final programme and informing the presenters of acceptance or not.

I’m glad to hear that all sessions will get feedback. In the past, feedback on session descriptions has helped me improve both the session itself and its description. See e.g. the differences in the way we described Balancing Act the first edition written more from an organisers perspective and the second edition more compact and focused on tangible outcomes for the attendees.

How and when to involve the program committee in the review process was/is a puzzle for xp days benelux. This year some of us waited for the other reviewers to get started, and then the committee reviewed the remaining sessions. For next year, we’re toying with the idea on starting first, to encourage other reviewers to also start early.

After a fairly open review process and animated discussion in the program committee, the XP Day Belenux 2005 Program is now online.

The only ‘regret’ I’m having about the program, is that I’m not going to have time to attend many sessions, since I’m co-hosting three fun-filled active sessions myself :-) :

• Gummibears
• Drawing Carousel
• Balancing Act

I’m proud of our more open review process this year, where we invited every session organiser to participate in the review process. We did the reviews on a wiki, so that everyone who bothered to review could see how others were working on reviewing sessions.

We were also happy to have plenty of sessions to fill two days instead of one. I’m hoping the program has a bit more air, and the participants have more time to meet each other (e.g. during the conference dinner on Thursday night).

XP Day London is taking this a step further, they are experimenting with a voting system (everyone who sends in a session gets five votes) and have made reviewing obligatory if you want to have a session accepted. I applaud their courage and am curious to find out how this worked for the program committee.

Sending in and reviewing was fun anyway. The program is not finished yet, reviews have closed yesterday. So far it looks like Balancing Act and The Agility of Domain Specificic Languages seem to stand a good chance of being accepted, since they each attracted five votes. Temperature Reading got three votes so far.

As a session organiser, I see one drawback in the voting approach – the Gummibears session description didn’t attract votes in London. It also didn’t attract any feedback, so it’s difficult to learn something for a possible next description.

Some sessions seem to have attracted feedback without votes, possibly because they are more controversial, or don’t fit well with the theme of the conference.

Anyway, exploring what works and what not in sessions, their descriptions and creating a conference program remains fascinating. I hope to write soon about how Rob Westgeest and I use mini-retrospectives to incrementally improve the eXperience Agile course.

Keith Ray wrote about Scott Berkun’s essays . I am particularly drawn to why smart people defend bad ideas . It describes some common ways of bad idea defenses, and some countermeasures. And it’s fun to read.

I don’t believe there is anything wrong with having bad ideas. I know I’ve had plenty. If you try to have only good ideas, you’ll be blocked. Generating many good and bad ideas, and deferring determination of their goodness or badness is key to techniques like brainstorming, working in iterations and pair programming.

I believe the key is in defending bad ideas. I know I’ve done that too… Once you find out, through ruminating or feedback from the real world that an idea might be bad, you need to reconsider, or generate new ones. At least you have to be open to the possibility that an idea might be bad.

I’ve also been on the receiving end of other people defending bad ideas. I guess it’s a bit more obvious if you receive the “defense”. Actually the “defending” often feels more like an attack in disguise. It often goes through manipulation. Scott describes several manipulations, some of which I’ve encountered often. I may have used them as well, but I’m not really aware of that – manipulation works best if the one who manipulates isn’t aware of it…

[..] Worse, if they got away with it when they were young (say, because they were smarter than their parents, their friends, and their parent’s friends) they’ve probably built an ego around being right, and will therefore defend their perfect record of invented righteousness to the death. Smart people often fall into the trap of preferring to be right even if it’s based in delusion, or results in them, or their loved ones, becoming miserable.

So, the next time you’re attacked by someone defending a bad idea, have pity on them. It probably hurts them much more than it hurts you.

The next time you feel miserable defending an idea, think again… It may be a real bad idea to defend this one…

While reading getting things done I came across this quote, which aptly summarizes the workshop experience:

It is easier to act yourself into a better way of feeling, than to feel yourself into a better way of action. - O.H. Mowrer