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Bernard commented on my thoughts on schema evolution.

I do not see why schema evolution is harder to handle in Prevayler than it is with a relational database. Changing relations is always a problem whatever the storage strategy you use.

Hmm, let’s see. Maybe I was very using traditional thinking. My thoughts were that it is easier to transform bare data as it is less to transform. You take the old data and insert it into the new code, which is all you need because you don’t want the old implementation anyway.

We’re right now trying out Prevayler as a persistence layer for our products. It is basically the coolest think I’ve seen since I became an OO-afficionado. I did start out with Smalltalk, and it sort of set the tone for what I believe in.

I need to check out if Jon has mentioned this on his blog. Nope, he hasn’t so I’ll be first then.

Here we go: What Prevayler basically does is store your object graph in memory, recording every transaction as a serialized Command. Every 24 hrs a snapshot of the full object graph is written to disk and the log is cleared. Crash recovery is performed by taking the latest snapshot and redo all the commands that is deserialized from the log.

Man bör lyssna på Kinks “I’m Not Like Everybody Else” åtminstone en gång i veckan.

… och man bör hålla med.

Jon and I had a pretty heated discussion today over serialized objects. The background is as follows:

Using Prevayler, you will have a file on your disk with your serialized object graph. This stores the state of your application, but, very important, also the implementation of that state. When deserializing the object graph, you do not retrieve properties that are set on “new” objects, you are retrieving the object itself. Like, duh.

Var på herrmiddag hos Henrik D igår, otroligt trevligt och makalöst god mat. Dock visar det sig dagen efter att man inte riktigt hänger med som man gjorde förr. Huvudvärken släppte lite lagom när jag var med Ellinor och babysimmade - 30-gradigt vatten är bra för kroppen.

Jag har passerat 33-årsstrecket och är nu riktigt 30-something. Känns förvänansvärt bra. Jag tror att mångas 30-årskriser är helt onödiga, det visar sig att det faktiskt är roligare att vara 35 än 25.

I’ve always been a fan of Netscape, but at the same time I never liked the Communicator idea - everything in one package. I don’t have a one piece stereo either, I’m just not that kind of guy. The Phoenix webbrowser is just right for me, it’s fast and lightweight and does not bring anything else down with it if something goes wrong. If Mozilla blows up it takes the mail session with it. If, using Windows, IE blows up everything is gone, reboot and grab a coffee.

I looked at the logs for freeroller and realized that 75% of client OS’s accessing it was Windows. This is of course a lower percentage than would be expected from a more generic set of computer users (I assume we’re all geeks here, right :-), but still, 75%.

I most certainly don’t want to start another Windozesuckslinuxisugly debate, but I was thinking that most sites accessed on freeroller have a strong connection to Java, and often business system Java - as opposed to embedded etc.

There has been a lot of talk about news aggregators. Personally I’m using Amphetadesk which does the trick and more. One must know the little secret to using it though. The basic setup works just fine, but the fun starts when you go for this addon which adds expand/collapse of news feeds, time since posting etc.