java.util.UUID.randomUUID().toString();

and set directly either as a field variable on instantiation or sometimes in an interceptor on save.

On a recent project we had to migrate some data across some new entities and needed something outside the application to generate the UUID values for each record. I knew that PostgreSQL supported UUID generation – though I had never used this before – and even has a UUID data type. Getting to the function itself proved a little more challenging as it isn’t actually included on a typical installation and is found within the postgres-contrib package. So, to install…

apt-get install postgresql-contrib
sudo su -c "psql pdrivers < /usr/share/postgresql/8.4/contrib/uuid-ossp.sql" postgres

The above installs the relevant contrib package, and creates the UUID functions from the script within the unpacked contrib directory (substitute version as required). We are also installing the function as a superuser (postgres in this case) as we need a user with the ability to install functions using C code.

To generate UUID values execute as follows:

SELECT uuid_generate_v1();

c1b84d24-90c9-11e0-aa50-33cd7e76d901
e9e3b374-90c9-11e0-8f0f-df46bcf47f20
eea6fba0-90c9-11e0-9ce0-a33175edde97

Some good references on the available functions can be found here with some further info on the package OSSP UUID pages here.

unknown configuration node //DB2

At this point i was thinking how the hell did VirtualBox know about my DB2 installation – assuming that my DB2 database installed on that VM was an issue. A little confusing here too given that i would get the VM window and then it would just close so it wasn’t getting anywhere near starting the OS – WindowsXP.

Anyway a bit of digging about and then this:

takisd@fitter:~> VBoxManage getextradata WindowsXP-1 enumerate
Key: GUI/LastCloseAction, Value: powerOff
Key: GUI/LastGuestSizeHint, Value: 640,480
Key: GUI/LastNormalWindowPosition, Value: 1437,47,640,527
Key: GUI/LastWindowPostion, Value: 1422,111,1224,867
Key: GUI/MiniToolBarAlignment, Value: bottom
Key: GUI/MiniToolBarAutoHide, Value: on
Key: GUI/SaveMountedAtRuntime, Value: yes
Key: GUI/ShowMiniToolBar, Value: yes
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/DB2/GuestPort, Value: 50000
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/DB2/HostPort, Value: 50000
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/DB2/Protocol, Value: TCP
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/Firebird/GuestPort, Value: 3050
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/Firebird/HostPort, Value: 3050
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/Firebird/Protocol, Value: TCP
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/Oracle/GuestPort, Value: 1521
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/Oracle/HostPort, Value: 1521
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/Oracle/Protocol, Value: TCP
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/SQLServer/GuestPort, Value: 1433
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/SQLServer/HostPort, Value: 1433
Key: VBoxInternal/Devices/pcnet/0/LUN#0/Config/SQLServer/Protocol, Value: TCP

…where WindowsXP-1 is the name of the virtual machine.

So all my intalled DBs on that particular VM had a setting on them for respective ports. I use most VMs for testing against various databases for various apps and mainly for Execute Query.

I vaguely recalled setting these some time ago – probably as a network response for forwarding – either way i didn’t really remember and resetting these with empty values fixed the problem like this:

VBoxManage setextradata WindowsXP-1 "VBoxInternal/Devices/pcnet/0/LUN#0/Config/DB2/GuestPort"

…and so on for the other nodes. Restarting the OS worked just fine and I now have my VMs back. Not sure if this documented anywhere by Oracle – quite the gotcha for seemingly simple upgrade.

…and here i was thinking WTF did Oracle do now…

Frankly, I don’t know for sure which particular package was the culprit. There was nothing logged that pointed to any issues – indeed any and all logs I went through indicated all was well. I also could not find a single thing online that resembled what I was experiencing. I have managed my own servers for about 10 years now. I’m far from a competent Linux admin but I usually know enough to get by or just enough to get out of trouble, so I became severely frustrated when a seemingly simple upgrade could result in all my sites being made unavailable.

I started by stripping back my Apache install to next to nothing – which brought back a single static site i set up as a test. Then line-by-line I reintroduced various modules, includes and various directive lines. At the very bottom I had my mod_jk include – which by the way serves over half of my sites.

As soon as I reintroduced mod_jk it dumped. After much fiddling, rebuilding mod_jk, installing from rpm, downgrading packages, tinkering with various mod_jk parameters, using strace on startup (great article on debugging with strace here) I finally put it down to the inclusion of the following:

<Location /*/META-INF/*>
    Deny From All
</Location>
<Location /*/WEB-INF/*>
    Deny From All
</Location>

The above tells Apache as a global directive to disallow any access to the protected Java web application directories WEB-INF and META-INF.

The lines above have been a part of my apache/mod_jk config for as long as I remember. I haven’t yet had a good look as to why the above is no longer acceptable – I’m just relieved to have everything back up. I would have expected Apache to complain about configuration errors, issue the relevant message and fail to start just like it does for most other issues. Not so in this case and furthermore it silently takes down the whole server instance.

I didn’t find any references to this anywhere – perhaps this will help someone equally confused as I was

Admittedly when registering on a new site I almost always just cut and paste my password into the repeat password field. Indeed with various systems now insisting on specific character patterns, i would imagine the purpose-defeating practice of cut/paste into the repeat password field is only more prevalent. The Smashing piece includes a JQuery plugin that allows for a single password field that may be toggled to show the entered password – definitely worth a look.

The login user name suggestion is much simpler – allow users the ability to login with either a user name or email address – both should be unique in any case and your email address is certainly harder to forget.

Check the article out here — Innovative Techniques To Simplify Sign-Ups and Log-Ins.

Some other useful login/sign-up resources i’ve found useful in the past are listed below.

• http://www.smashingmagazine.com/2008/07/04/web-form-design-patterns-sign-up-forms/
• http://www.hongkiat.com/blog/login-registration-form/
• http://www.smashingmagazine.com/2009/06/23/10-ui-design-patterns-you-should-be-paying-attention-to/

In my subsequent travels i found Favicon Builder.  Simply upload a gif, jpg or png image and it generates a favicon that rendered perfectly. The generated download is a zip archive with a readme file, animated icon as a gif, favicon ico and a couple of scaled png files. Very nice

This created a little bit of fuss on the various lists and a few bug reports at bugs.debian.org. Some of the more informative ones can be found here and here.

In short, the change was documented in the package NEWS and README files with hints to check out the post script sample scripts and apply these to the relevant directories in /etc/kernel.

I copied over the following:

/usr/share/kernel-package/examples/etc/kernel/postinst.d/initramfs

to

/etc/kernel/postinst.d

and

/usr/share/kernel-package/examples/etc/kernel/postrm.d/initramfs

to

/etc/kernel/postrm.d

From there just a normal build and install and all was well.

Uncle Bob of ObjectMentor has posted a quick demo here.

You can download either a WAR file or pre-packaged for your distro including RPMs and Debian packages. Well worth a look.

From a post with the same name, check out this entry from Joel on Software.

Cracker!

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