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Category: How To

Tapestry Quickstart

As preparation for a recent interview, I decided to attempt to download, install and run an example Tapestry web application. I set aside a couple of hours to get this going. I expected to have to download an installation bundle, extract it, run an installer, install some dependencies, install and configure a webserver, start some services, write some code, debug, swear a bit then give up and just read an online tutorial.

As it happens, all you need is Maven 2. Running two goals with no particular config will download Tapestry and all dependencies, build and deploy a sample webapp and then run it in a webserver (which it will install too!).

Spring-WS SAAJ problem in JBoss

I recently used Spring-WS in an application that we wanted to deploy under JBoss 4.0.1sp1 / JDK 1.5 and JBoss 5.1.0GA / JDK 1.6. I had a good few problems getting the dependencies just right but the biggest problem was with SAAJ.

If you’re running JBoss 4.0.1sp1 and JDK 1.5, you’ll need to package a SAAJ implementation with your app. Easy enough. However, if you’re running JBoss 5.1.0GA and JDK1.6, you don’t want to include a SAAJ implementation as it’s included in the JDK 1.6 release. Also easy enough? Er no.

Maven 1 to Maven 2

I’ve been using Maven 1 for close on to five years now.  I’ve been meaning to upgrade to Maven 2 for pretty much all of that time but never quite got round to it. A combination of my starting work on a new project and finding some nasty bugs in Maven 1  has finally nudged me towards Maven 2.

Surprisingly, in my team of around a dozen developers, we’ve had only minimal exposure to Maven 2. Everyone has stuck loyally to the now completely obsolete and unsupported Maven 1. I think everyone hopes someone else will do the hard work first.

As we have dozens of build projects in our repo I can’t migrate them all at once. I’m just doing my project and its immediate dependencies. Unfortunately, this causes problems for the old Maven 1 projects as Maven 2 repos are not compatible with Maven 1. So during the transition period I must ensure that both old style Maven 1 projects and new style Maven 2 projects have access to their dependencies from one or other of the repos.

Resizing a virtual hard disk

No matter what size hard disk you have, sooner or later you’ll find it’s too small. This is just as true for virtual hard disks as it is for physical ones. One of the benefits of virtialization is that you can change your ‘hardware’ setup on a whim. Want an extra gigabyte of memory? No problem, just assign it in your virtual machine config. So long as your host machine has capacity and the guest O/S supports it, this is easy to do.

Frustratingly though, none of the main VM software vendors (VMWare, Microsoft Virtual PC / Server and Sun VirtualBox) offer a way to resize a disk from the standard user interface. It is possible, but it takes a little fiddling to get it to work.

Memory usage

A year or two back I was working on a web application which was expected to have moderate use – around 50 concurrent users. The product was generally getting thumbs up from our QA guys. It did everything we expected it to do. Then we had a go at testing under load.


We found that if we had only a few users hammering the system for any length of time, the memory usage became unacceptable. Simple maths showed that the problem was to do with the number of open sessions. Each session required 20-30MB of memory from the app server. This is a piddly small amount when we have a handful of test users. It went completely unnoticed against the background noise of a typical server’s memory use. However, once just a hundred sessions have been opened (not necessarily at the same time) we’re chewing gigabytes at a time.

JUnit testing Hibernate and Spring

Here’s a nice recipe for unit testing Spring configured Hibernate. It allows me to neatly test my Spring configured DAOs and reuse a lot of the Hibernate Session and Transaction configuration beans from my production code. This saves having to rewrite it for my tests and also makes the tests more realistic. I’d rather test my production code rather than use mocks as far as possible.

Installing WordPress

This is post number four and I’m going off topic already. This post is a technical note on how to install WordPress on a desktop PC.

After installing WordPress on my hosting service (hosted on Easily if you’re interested) I wanted a copy on my home PC as an offline backup and to generally fiddle with. As I’m likely to zap my PC soon (Vista is dead, long live Windows 7) , I’m keeping a note of how I did this.