Prevent your webform from showing the “are you sure you want to leave this page” message

When a webpage in your application detects changes made to input items (if they are valid or not), it will present the user a popup asking if he/she wants to leave the page or stay on the page. Although that is useful in many cases, sometimes you just want to switch it off on  a specific page. The solution is really easy.

Place the following Javascript in the onLoad event of your page:

window.onbeforeunload = null;

In for instance, Application Express, you can put it in the Execute when page loads item in the Javascript section of your page.

If you want to show a different message, just replace the null with the message between double quotes.

New whiteblog: Setting up Oracle Stream Explorer 12.1.3

Last friday I put a new blog on the Whitehorses Blog:
Setting up Oracle Stream Explorer 12.1.3

It helps you install and configure Oracle Stream Explorer, which is a new graphical layer on top of Oracle Event Processing. OEP is a powerful real-time analysis and monitoring tool for real-time data. Go check it out!

Format an SD Card to FAT32 in OS X

If you want to format an SD Card to FAT32, and you can only select FAT16 (among other choices) in Disk Utility, issue this command from the command line:

First find the name of your disk with “df”.  The result is something like this:

iMac-van-Patrick:dev patricksinke$ df
Filesystem 512-blocks Used Available Capacity iused ifree %iused Mounted on
/dev/disk1 1951190584 1138759280 811919304 59% 142408908 101489913 58% /
devfs 382 382 0 100% 662 0 100% /dev
map -hosts 0 0 0 100% 0 0 100% /net
map auto_home 0 0 0 100% 0 0 100% /home
/dev/disk4s1 1983232 3072 1980160 1% 512 0 100% /Volumes/NAAMLOOS 1

The disk label is “NAAMLOOS 1”, so I know the filesystem name is /dev/disk4s1.


diskutil eraseVolume "MS-DOS FAT32" FAT32disk /dev/disk4s1

Where FAT32disk is the new label. You’re set and done.


Fix all your “cannot open shared object file” problems in Linux

After installing Oracle XE on Linux, and especially Ubuntu, you might find yourself with issues opening SQL*Plus and other tools.

“sqlplus: error while loading shared libraries: cannot open shared object file: No such file or directory”

There are many possible reasons for that, so check the following:

Set your paths correctly

Perform the commands:

oracle@VirtualBox:~$ echo $ORACLE_HOME
oracle@VirtualBox:~$  echo $LD_LIBRARY_PATH

If these are empty, go to your Oracle home and enter:

sudo ./

This wil set all the environment variables. Sometimes you get the error

./ 1: /home/oracle/app/oracle/product/11.2.0/dbhome_1/install/utl/ /bin/awk: not found
./ 1: /home/oracle/app/oracle/product/11.2.0/dbhome_1/install/utl/ /bin/awk: not found
./ 127: [: !=: unexpected operator

When this happens, enter “which awk”  to find the path where awk is located, edit the file <Oracle_home>/install/utl/, look for the line
And replace the path with the output from the “which awk” command.

Now all your paths and environment settings should be correct.

If not, this might me a good time to reinstall the database software. Chances are some files are corrupted.

The latest Whitebooks: Oracle B2B 12c – new features and Managed File Transfer (MFT)

The latest Whitebooks are published on the Whitehorses Blog.

The first is by Dirk Janssen and he demonstrates all the handy features of Managed File Transfer (MFT). He mentions some pitfalls in using MFT, so it’s definitely worth reading.

The second is by me! This time it’s an article about the new features of Oracle B2B 12c. It’s more than just a messaging portal, with all the security features and support for many types of protocols. And in 12c new features like large message formats, better integration in SOA Suite 12c and Default Channels are worth investigating.

Both articles are in Dutch (sorry for the rest of the world!), but you might hand them over to Google Translate to make them readable in your language of choice. They also contain interesting references to several English sites. Check out these and many more Whitebooks on

2 new Whitebooks: Advanced Service Scheduling in SOA Suite 12c with ESS and Integration of SOA with Oracle Event Processing in 12c

In case you missed it, last month two new articles were published on the Whitehorses website.
The first is by Laurens van der Starre about how the SOA architecture in Oracle SOA Suite 12c can be combined with an Event-Driven Architecture. In the fast-flowing world of Big Data and the Internet of Things, Oracle Event Processing can be used to analyze large data streams in realtime. How to achieve this is explained by Laurens here.

The second article is written by Michel van Zoest, explaining how you can leverage all the new features of the Oracle Enterprise Scheduling Services (ESS) and schedule jobs from the Enterprise Manager, being it Web Services, command line scripts or Enterprise Java Beans. Read all about it here!

Both articles are in Dutch (sorry for the rest of the world!), but you might hand them over to Google Translate to make them readable in your language of choice. They also contain interesting references to several English sites. Check out these and many more Whitebooks on

Je Suis Charlie.

Because we can not allow this.
Because freedom of speech is our most valuable asset. The thing that makes us really free and defines who we are.
Because no one has the right to insult, but also not the right to be insulted.
And most important, no one has the right to take someone else’s life, just because he disagrees with another person’s values.

Charlie Hebdo is a French satirical newspaper. People died there today because they defended free speech. We can not allow this.

My thoughts go out to the victims and their family.
Je Suis Charlie – I Am Charlie.

Je Suis Charlie - I am Charlie. For free speech.

Installing Guest Additions fails on Oracle Enterprise Linux 7.0

If you install the Guest Additions modules in a Oracle Enterprise Linux 7.0 virtualbox, you might encounter the following problem:



The main Guest Additions does not build. When checking /var/log/vboxadd-install.log, there should be something like:

/tmp/vbox.0/Makefile.include.header:97: ***Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR=<directory> and run Make again. Stop.

Not very helpful, is it? The most straightforward solution is to update the kernel-uek-devel package to your Linux kernel version with the command

yum install kernel-uek-devel-`uname -r`

installing kernel-uek-devel package

Afterwards, Guest Additions module was successfully installed.



Building the main Guest Additions module Successful
Building the main Guest Additions module Succesful

Restart your Virtualbox instance in order to apply all the changes.

Addition: This problem can occur on Ubuntu too. To fix it there, issue this command in a terminal:

sudo apt-get install build-essential linux-headers-`uname -r` dkms

Fix Linux environment settings on Oracle database – once and for all!

I’ve worked in so many environments where the Oracle environment  variables are not set correctly.  Especially all the preinstalled Virtualbox instances floating on the interwebs.
Consequence is that tools like sqlplus cannot be found from the command line or don’t work at all. There’s no need for that, because the solution is really, really easy. There’s a little script called oracle_env in the bin directory (usually something like /u01/app/oracle/product/11.2.0/xe/bin) that sets it all right for you.
When you add the following line to the .bash_profile in your home directory, all parameters will be set when you log in.

. /u01/app/oracle/product/11.2.0/xe/bin/

Don’t forget the dot and space at the beginning of the line.

Although this information is mentioned in the installation guide, I thought it might be worth mentioning.