Phone Line Repair and MaxDSL Speed

Last wednesday evening our phone line went dead along with our ADSL service. So the next day we called our provider and asked them to test to line and after a little nagging they got on to BT and had the line tested on Friday, they say there is a fault on the line and an engineer needs to be called. They said an engineer would be out to us on Wednesday of the following week. I was not impressed. Anyway it turns out that a BT engineer appears around lunch time on Sunday and after a while fixes the phone line. After he's left I reconnect the ADSL and find that it isn't working, thankfully he gave us his mobile and so we drop him a call. He says that it will probably need another engineer to look at it tomorrow as nobody who knows about the ADSL stuff is about on a Sunday. Monday morning I get up and discover that the ADSL is working, great. However looking on the router it is syncing at 3584 Kbps/640 Kbps. As I mentioned in previous post I was getting allot more (it settle down to around 5500Kbs/448Kbs), so although I now have working internet access again I have lost 2Mbps in the process. I suspect that there isn't anything I can do about this as the line works fine, just not as well as it used to.

Building Tomcat 5.5 from SVN problem

I was attempting to build Tomcat 5.5 from SVN using the instructions from tomcat pages, however I was getting an error of: /home/buckett/src/tomcat/build.xml:49: The following error occurred while executing this line: /home/buckett/src/tomcat/build/build.xml:791: The following error occurred while executing this line: /home/buckett/src/tomcat/container/webapps/docs/build.xml:88: java.lang.ClassNotFoundException: org.apache.tools.ant.taskdefs.optional.TraXLiaison after a little head scratching I discovered that I had installed ant as an Ubuntu package and I was missing the ant-optional package which provided this extra functionality. After intalling this additional package everything went smoothly.

Bodington Database Objects and User Importer

I am currently working on some new user import code for Oxfords installation of Bodington (WebLearn) which takes a feed of about 35000 users and creates accounts and groups for them. Due to the large number of users involved and the small number of changes that are made each day it is important to try and keep the import running fast. At the moment the bottleneck seems to be the database which eats up most of the CPU during the import, a quick look at a process listing shows PostgreSQL using 80% or the CPU and Java using 10%. Looking at the statement logging it seemed that for each user it was always updating the user in the database even if nothing had changed. Update statements are expensive for a database compared to select statements so cutting down the number of updates seemed an obvious way to improve the performance. Every object that is stored in the database by Bodington extends org.bodington.database.PersistentObject which provides the skeleton for database objects One feature of PersistentObject is that it keeps track of wether an object has unsaved changes or not. This is done through calling the setUnsaved() method which is done by most setters of the subclasseds. Eg: public void setName(String name) {   this.name = name;   setUnsaved(); } Now this means that even if the name is set to the same value the object is flagged as being unsaved. One option would have been to have add checking to the userimporter so that it only updateded the name of a user if it was different to the current value: if (!user.getName().equals(newName))   user.setName(newName); However there is no reason why other sections of Bodington shouldn't make use of this checking and it is also a database issue so I moved this code into the setter and ended up with: public void setName( String name ) {   if (name == null)     throw new IllegalArgumentException("Name cannot be null");   if (name.equals(this.name)     return;   this.name = name;   setUnsaved(); } The checking to see that if name == null is because the database has a NOT NULL constraint and this also prevents a NullPointerException from being thrown if setName(null) is called. I added this checking to org.bodington.server.realm.Users and org.bodington.server.realm.Aliases and a quick test of updating 1000 users gave the results:

• Always Saving: 1minute 3 seconds.
• Saving Changes: 30 seconds.

which isn't a bad improvement in performance. One side note is that PersistentObject.save() always saves the object and I could have changed it so that it only saved changed objects but I'm not sure that all the setters of the subclasses call setUnsaved() so I am doing my checking in the importer. The group mapping has come wholesale from some old user import code with a few changes and just needs a little tweaking and it should be nearly ready for some proper testing.

Glassfish and Invalid URL Pattern

I was attempting to deploy WebLearn to the Glassfish application server and was gettting the error "Invalid URL Pattern" for /site/* which is used in various places in our web.xml configuration file. It turns out Glassfish doesn't like extra whitespace in it's url-patterns and we had things like: <url-pattern>   /site/* </url-pattern> when they need to be: <url-pattern>/site/*</url-pattern> I've got the web.xml fixed on WebLearn and will push it across to Bodington at shortly.

Ubuntu Dapper Drake Upgrade

With Ubuntu Dapper Drake being released on the 1st of June I decided to upgrade my work desktop machine today. I just edited my sources.list file and then ran apt-get update; apt-get dist-upgrade. Most of the upgrade went fine, but here are a few things that other people may fin helpful were. nVidia Monitor Detection It seems that the new nVidia driver was autodetecting that my monitor could do 76Hz vertical refresh rate at 1280x1024. Not while it can display this it didn't seem to be able to adjust the screen enough and as a result I was unable to see the two left most columns of pixels. I attempted to fix the vertical refresh rate in my configuration file ( /etc/X11/xorg.conf ) by setting the line VerticalRefresh 50-60 but every time I started X up it would continue to use 76Hz which was outside the range. After quite a bit of Googling I discovered that the nvidia driver attempts to autodetect the monitor settings by default and the way to turn it off is to add an option to the file: Section "Device"   Identifier "NVIDIA Corporation NV18 [GeForce4 MX 440 AGP 8x]"   Driver "nvidia"   Option "UseEdidFreqs" "false" EndSection Pinned Rhythmbox Somehow rhythmbox was pinned in the Synaptic Package Manager, this didn't seem to be affecting apt-get which was upgrading it without any problems. The problem turned out to be that synaptic can have its own list of pinned applications which are stored in /usr/lib/synaptic/preferences. As this only entry in this file was the pinning of rhythmbox I deleted the file and everything worked fine. Packaged Java Ubuntu now packages the Sun JDK which can be install just like any other package. I had a problem though in that all my alternatives (/etc/alternatives) were pointing to the wrong versions. I found a good post on galternatives that allows you to easily edit them.

User Import and Bodington Developers Meeting

The user import code is coming along, last week I added parsing of colleges, courses and departments and some tests against small bits of data. The status handling has also been sorted out so rather than working with strings they are converted to an enumeration. Most of last week was taken up by a Bodington developers meeting in Leeds. The meeting went over two days with the first day being for discussion of short term Bodington developments and the second day for the longer term Bodington vision. Out of the first day we decided to release Bodington 2.8 shortly, most of the code is already in CVS for Bodington 2.8 so once a few extras have been added and some tested has been performed 2.8 should go out the door. Other things discussed included a catchup on what developments have been happening at the various sites that run Bodington and the JISC projects that are using it. The second day we discussed longer term direction including Portals, SOA, SOAP, REST. At the end of the day I just want to build a better product.

I owe PayPal money

I owe PayPal 56 pence as a result of a currency conversion charge from a long time ago I think. Today I recieved an email nagging me to correct my balance and decided to attempt todo something about it, so I login to my account and attempt to add funds but it refuses to allow it just returning me to the form highlighting the fields that I have filled in sucessfully. So I looked at the email that PayPal had sent me and noticed it ended with: We appreciate your cooperation and invite you to reply to this email with any questions. Yours sincerely, PayPal Please do not reply to this email. This mailbox is not monitored and you will not receive a response...... So I replied to the mail and we'll see how we get on. They do accept cheques to fix my balance but I signed up with PayPal to get away from cheques....