Computers and dates

Here follows a very useful link about Julian day numbers: http://www.hermetic.ch/cal_stud/jdn.htm. This explains why julian day numbers apply to a timeframe that has 7980 years. This is often referred to as the Julian period or Scaliger cycle.

The joys of Open Access

I have been clearing out my mailbox of old reference articles, useful links etc and came across this one about Open Access: http://www.earlham.edu/~peters/fos. This is of interest (to me anyway) after my work on Digital Libraries.

Searching PubChem

Here is a useful link for how to search PubChem. http://acdlabs.typepad.com/my_weblog/2008/02/dereplication-v.html. The focus is on having an unknown sample with some NMR data. Well, I thought it was interesting, anyway, especially in the light of my recent work on a Digital Library for a major publisher.

Free news server (NNTP) access

Most UK ISPs have never heard of newsgroups. They think the internet == the web. Duh! So it is very difficult these days to find an NNTP server. This note is to remind me of which one I am using at the moment. Currently it is nntp.aioe.org. I will update this page as this changes over time.Free newsgroup servers do tend to get shutdown eventually (sigh).

getting mySQL set up on ubuntu

It is too painful to setup mysql via a source code build so I used a non-RPM install. It didn't quite work out of the box. Here's what I did: groupadd mysql
useradd -g mysql mysql
cd /usr/local
gunzip < /path/to/mysql-VERSION-OS.tar.gz | tar xvf -
ln -s full-path-to-mysql-VERSION-OS mysql
cd mysql
chown -R mysql .
chgrp -R mysql .
scripts/mysql_install_db --user=mysql --basedir=/usr/local/mysql --force
chown -R root .
chown -R mysql data
bin/mysqld_safe --user=mysql &
This last step was an attempt to start up the mysql server. It failed, as can be seen by the next command and its output. bin/mysqladmin version
bin/mysqladmin: connect to server at 'localhost' failed
error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)'
Check that mysqld is running and that the socket: '/var/run/mysqld/mysqld.sock' exists!
On with an attempt at a fix: touch /var/run/mysqld/mysqld.sock
chown -R mysql /var/run/mysqld/
bin/mysqld_safe --user=mysql &
THIS DIDN'T WORK. Error log said:
[ERROR] Can't find messagefile '/usr/share/english/errmsg.sys'
fixed by saying:
bin/mysqld_safe --user=mysql --language=./share/english &
Now I can connect. All I need to do now is put this into the bootup sequence....

How to rollback a changeset in subversion

Suppose you want to rollback the changes in changeset 2340. You checkout the HEAD into some working directory, then do the following:
svn merge -c -2340 .
svn ci -m
Then you will probably want to set up the working copy so it has the changes you rolled back so you can fix whatever was wrong. Here's the command you use:
svn merge -c -2340 .
This is not very obvious to the beginner. It is done using merge rather than revert. The svn revert command is used to revert uncommitted changes.

How to solve a weird JAXB/xerces spring application context load error

I was trying to get an app working standalone a spring application context via the classpath. In eclipse it worked fine but at the command line I got:

Unable to validate using XSD: Your JAXP provider [org.apache.crimson.jaxp.DocumentBuilderFactoryImpl @148cc8c] does not support XML Schema. Are you running on Java 1.4 or below with Apache Crimson? Upgrade to Apache Xerces (or Java 1.5) for full XSD support.

I was using java 1.6 and the latest Xerces so this error message is not at all helpful. What was VERY helpful was finding the thread at http://forum.springsource.org/archive/index.php/t-21140.html which contained the answer. I need to define a couple of properties that force the factories for XML parsing. Just add the following as JVM parameters:

-Djavax.xml.parsers.DocumentBuilderFactory=com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl
-Djavax.xml.parsers.SAXParserFactory=com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl

How to have an iPod without using iTunes

I trashed Brenda's iPod today. I eventually managed to recover it. Here's what happened:
I ripped a couple of CDs and copied them to the iPod using gtkpod. This was an experiment. I had always used iTunes before, but I am trying to escape from Windoze so I wanted to see if I could use some open source software on my Debian machine. I found that although the iPod contained the new music, once the iPod was supposedly synch'd then disconnected, the iPod reckoned the music wasn't there. As I tried various approaches eventually the iPod reckoned there was no music on there at all. Even doing a factory reset didn't fix it. On my travels I found stories of people who had managed to get iTunes up and running on their system using wine. That didn't work for. For a start, the Etch version of Debian has a version of wine that is too old. I tracked down a backport and I used winetricks to fool the system into thinking I am on XP, which the iTunes installer requires. But iTunes could not fix the iPod with the state it had gotten into, and IMHO iTunes is rubbish anyway.
Eventually I found out that the problem is caused by Apple turning the iPod against me. They want it to work only with iTunes and they keep revising the firmware to make it not work with other software. This is behaviour worthy of the Evil Empire itself. Brenda's iPod is a fourth generation nano. That means it has all the latest stuff to prevent people being able to use the device without using Apple software.
I found that some kind people have backported a recent version of gtkpod to Debian Etch. The glibpod3 library required has also been backported. I downloaded and installed the Debian packages. The next and final trick was to update a crucial file on the iPod which is used to identify the firewire device. I mounted the ipod to /med/ipod. This made the pathname of the file to be /media/ipod/iPod_Control/Device/SysInfo. Run the command "sudo lsusb -v | grep -i Serial" (without the "") with your iPod plugged in, this should print a 16 character long string like 00A1234567891231. This is the id. Put it in that file in the form:
FirewireGuid: 0xffffffffffffffff.
The leading '0x' is important.
I found this help at http://mandrivausers.org/lofiversion/index.php/t50594.html. Phew. At last, I can now use the iPod without Windoze and without Apple software.

managing photos without facebook or flickr

I got tired of the unreliable photo upload of facebook and found the bandwidth and size limitations of flickr too, er, restrictive, so I looked around for something else. I came across Coppermine Gallery and IMHO it is brilliant.
The online manual tells you exactly how to set it up and it worked first time. I am pleased to say it works with FastHosts (my webspace provider). There is a slight deterioation in image quality that you don't get with facebook or flickr. I think this is combination of me making smaller jpgs and the fact that Coppermine is using GD. It can use ImageMagic where available. I am not sure which one is supposed to be the best.
So, all I need to do now is add menu options to my web site to refer to the various albums.

The pain of building subversion on solaris

I have eventually managed to get subversion 1.5.0 built on solaris (opensolaris running on VirtualBox actually). At the time of writing this, the most recent version of subversion is 1.6.0. However, I have a requirement to use an older version of subversion, 1.5.0. This is because subversion, subclipse and svnant need to all cooperate with each other. This means dropping back to 1.5.0. When I tried to build subversion 1.5.0 on solaris I got a load of link time errors to do with relocatable code in libneon.a. I eventually found a blog at http://sreekalyan.blogspot.com/2005/07/installing-subversion-on-solaris.html which gave me a hint on how to solve the problem. First, I found I had to use version 0.28.1 of neon. The subversion configure does not like a more recent version and says neon is not there! By default, libneon does not build shared libraries. You have to configure with --enable-shared=yes, an undocumented option no less! I then deleted /usr/local/lib/libneon.a so that it could not be picked up by accident. After a configure in subversion I had to hack the value for the neon library, changing it from libneon.la to libneon.so. Wow, what a pain this was!

DSpace, chemical structures, CML and jmol

I have started to put some chemical structures into my DSpace instance. They are going in as CML files. CML is Chemical Markup Language. There is an open source tool called jmol which allows structures to be viewed as 3D rotating images, given a CML file. JMol includes a servlet so that web pages can display these images. I would like to see this used by DSpace. But in the meantime I have set things up so that CML files invoke an external jmol viewer. This is a bit like putting up PDFs and getting the external acrobat reader to display them. Here's how I did it:

• Add a mimetype for XML to the list of registered types. Make the type known (as opposed to unknown or unsupported), and the mimetype chemical/x-cml.
• Download the jmol package from sourceforge and ensure that the script jmol.sh (or jmol.bat on Windoze) has execute permission. On Windoze the environment variable JMOL_HOME must also be defined. On Unix just add the jmol directory to your PATH.
• Test jmol by running the standalone viewer on a CML file. When that works you should be ready.
• Add a CML item to a collection in your Dspace. That's it. Clicking on it will now run the viewer!

It would be great if the 3D image could be in the web page directly, like PDFs can with the browser add-on. But AFAIK there is no such add-on. There is the servlet but this would involve codes changes to DSpace.