February 2012 – Frankie Inguanez

Month: February 2012

Scanners/Printers on un-supported OS

Posted on 2012-02-12 by Frankie

Got a scanner, printer, all-in-one device that is not supported on your OS, maybe a new printer and you do not want to upgrade your OS. All is not lost!

For scanners try VueScan found at: http://www.hamrick.com/ It replaces the software bundled with your device and is supported on most OS.

For printers try Gutenprint found at: http://gimp-print.sourceforge.net/index.php Its an open-source project so might take some time for new printers to be supported, yet you might be lucky for your situation.

Common Oracle XE and Oracle SQL Developer problems

Posted on 2012-02-12 by Frankie

SQL Developer – Connections tab not visible
1) Do make sure that you have downloaded the version that includes the jre
2) Do make sure that you have the right version, there is a 64-bit version if you have a 64-bit system.
3) Do make sure that SetJavaHome has been properly set to the Java location on your system, the option is found in the SQL Developer configuration file \sqldeveloper\bin\sqldeveloper.conf (http://forums.oracle.com/forums/thread.jspa?threadID=1049872)

Oracle XE Home Page returns Error 404
If you are using NetBeans or Visual Studio and your web pages or Oracle XE Home page are returning a Error 404: Page Not Found you might want to try the following link: http://hubpages.com/hub/ASPNET-DEVELOPMENT-SERVER–WEB-PAGE-CANNOT-BE-DISPLAYED

Unknown Locale
If when attempting to connect you are getting a Locale not recognized error, make sure that your regional settings are set to English, Control Panel->Regional and Language Options, you also need to add the following to the sqldeveloper.conf file: AddVMOption -Duser.Xlanguage=en
AddVMOption -Duser.region=US
(http://forums.oracle.com/forums/thread.jspa?threadID=369603)

Access Denied error when starting Oracle Database
If you are getting an Access Denied error when starting the Oracle XE server you need to right-click on the “Start Dabatase” option and select “Run as administrator”.

Other Errors
It is know that some errors are particular to Windows Vista, if you still cannot get either Oracle XE or Oracle SQL Developer to work you might want to try to install a Virtual Machine, install an OS of your choice (recommended Windows XP) and install Oracle XE then Oracle SQL Developer.

Complete Un-installation of PostgreSQL from Mac OS X Lion

Posted on 2012-02-11 by Frankie

In response to a question on stackoverflow, here is a short guide on how to completely uninstall PostgreSQL 9.1 from Mac OS X Lion.

Open a terminal window
Utilities->Terminal
Run the uninstaller
sudo /Library/PostgreSQL/9.1/uninstall-postgresql.app/Contents/MacOS/installbuilder.sh

PostgreSQL Uninstall Wizard

PostgreSQL Uninstall Wizard in Progress

Data not removed after PostgreSQL Uninstallation
Remove the PostgreSQL and data folders (Wizard will notify you that these were not removed)
sudo rm -rf /Library/PostgreSQL
Remove the ini file
sudo rm /etc/postgres-reg.ini
Remove the PostgreSQL user
System Preferences -> Users & Groups

Unlock the settings panel by clicking on the padlock and enter your password

Select the PostgreSQL user and click on the minus button.

Virtual Hosts on Apache

Posted on 2012-02-10 by Frankie

Working on multiple Web Projects on the same system might become a headache to manage. You must use Virtual Hosts if you are using Apache as pointed out by David Kiss. Following are the steps required to create a Virtual Host called magento in your system such that when you type http://magento the site is displayed, as per Mac OS X Lion using MAMP:

Backup your files.
1. Open a terminal window.
2. Backup your hosts file:
  sudo cp /private/etc/hosts /private/etc/hosts.bak
3. Backup your Apache configuration file:
  cp /Applications/MAMP/conf/apache/httpd.conf /Applications/MAMP/conf/apache/httpd.conf.bak
4. Backup your Virtual Hosts configuration file:
  cp /Applications/MAMP/conf/apache/extra/httpd-vhosts.conf /Applications/MAMP/conf/apache/extra/httpd-vhosts.conf.bak
Update the hosts file.
1. Edit the hosts file:
  sudo nano /private/etc/hosts
2. Add the name of the Virtual Host you want on your system:
  127.0.0.1 magento
3. Save and exit:
  Press Ctrl+X then Y.
Update the Apache configuration file.
1. Edit the Apache configuration file:
  nano /Applications/MAMP/conf/apache/httpd.conf
2. Un-comment the line where httpd-vhosts.conf is found such that it looks like this:
  Include /Applications/MAMP/conf/apache/extra/httpd-vhosts.conf
3. Save and exit:
  Press Ctrl-W then Y
Update the Virtual Hosts configuration file.
1. Edit the configuration file:
  nano /Applications/MAMP/conf/apache/extra/httpd-vhosts.conf
2. At the end add the following:
  <VirtualHost *:80>
  ServerName magento
  DocumentRoot /Users/fraki/Sites/magento
  </VirtualHost>
3. Save and exit:
  Press Ctrl-X then Y
Place the site contents in the folder specified.
Navigate to the virtual host.

Virtual Hosts Navigation — Using Virtual hosts

You might want to check the official documentation of Apache about Virtual Hosts, in this post I am using name-based virtual hosts.

Configuring SSL for Apache on OS X Lion using MAMP

Posted on 2012-02-10 by Frankie

After self-signing an SSL certificate for development purposes the Web server needs to be configured appropriately. I found the posting by Dave Kiss to be the best one. Following are the required steps if you used the default MAMP settings:

Backup your configuration files:
1. Open a terminal window.
2. Go to the Apache configuration folder:
  cd /Applications/MAMP/conf/apache
3. Backup the Apache configuration file:
  cp httpd.conf httpd.conf.bak
4. Backup the SSL configuration file:
  cp extra/httpd-ssl.conf extra/httpd-ssl.conf.bak
Update the Apache configuration file:
1. Open the configuration file using an editor of your choice:
  nano httpd.conf
2. Search for the line containing httpd-ssl.conf:
  Press Ctrl-W then type httpd-ssl.conf
3. Uncomment the line by removing the # from the beginning such that it reads:
  Include /Applications/MAMP/conf/apache/extra/httpd-ssl.conf
4. Save and exit:
  Press Ctrl-X the Y
Copy the server.key and server.crt file to your Apache configuration folder.
Start the servers through the MAMP interface.
Navigate to your site through a browser using https:
https://localhost

Accept Certificate — Accept self-signed certificate

N.B. If the apache server fails to start then you have an error in your configuration, make sure you replace the DocumentRoot in your SSL configuration file to match your actual root folder.

N.B. Dave’s post also contains steps to configure Virtual Hosts which I left out for a different posting to be less confusing.

N.B. Dave’s post using git to backup the files, in this post I simply make a copy of the configuration file, if you want to restore the backup simply type: cp httpd.conf.bak httpd.conf or any other file you want to restore.

Configuring MySQL Workbench with MAMP on Mac OS X Lion

Posted on 2012-02-10 by Frankie

Installing MAMP on Mac OS X Lion is surely an easy way of getting Apache, PHP and MySQL working on your system. If you plan on using MySQL Workbench you will need to do some additional steps.

Create the missing my.cnf file.
1. Open a terminal window.
2. Create the file by typing:
  sudo touch /etc/my.cnf
3. Change the owner of the file to your username:
  sudo chown fraki /etc/my.cnf
Create a new server instance and shown in my previous post: MAMP, MySQL Workbench and WordPress setup guide
Edit the server instance settings as follows:
1. Set the MySQL Server start command to:
  /Applications/MAMP/bin/startMysql.sh
2. Set the MySQL Server stop command to:
  /Applications/MAMP/bin/startMysql.sh
3. Set the MySQL Server status command to:
  ps xa | grep “/Applications/MAMP/Library/bin/[m]ysqld”

: Configuring MySQL Workbench on OS X Lion with MAMP

Keep checking through the guide for additional configuration.

SSL Certificates

Posted on 2012-02-10 by Frankie

At some point any Web Developer would need to secure part of a site and therefore require an SSL certificate. There are different options available depending on the use and here is a short post documenting the various options:

Free for Open Source Projects: Some providers are willing to offer free SSL certificates for open-source projects such as GoDaddy.com, obviously some terms and conditions apply which one must read. More details can be found here.

Free with Hosting Plan: Some Web Hosting providers would include a free SSL certificate if you buy a hosting plan. Generally the offer is for the first year with competitive renewal pricing. Just to name a few: HostColor.com, DomainAvenue.com and HostGator.com

Free SSL Community: A growing community called StartSSL are offering an entry level service for free for basic used and limited warranty which might well satisfy your needs and therefore worth a check.

Comparison Charts: If none of the above suits you then you might have to actually buy an SSL certificate, not before doing the appropriate research. WhichSSL is a dedicated site to aid in the selection of the appropriate certificate authority or SSL vendor to choose with the help of a comparison chart. More comparisons can be found in Wikipedia.org and SSLShopper.com. Your research might also payoff by finding some promotional offers and/or discounts.

Self-Signed Certificates for Development: Well if you need a certificate just for development purposes then you can sign one yourself as shown in my previous post.

Self-Signed SSL Certificate

Posted on 2012-02-10 by Frankie

If you are planning on developing or customizing some web systems such as WordPress or Magento, then at one point you will need some security. You might want to sign the SSL certificate yourself. A number of guides exists for this, for Windows Systems I found the one by Shivprasad Koirala to be very intuitive and for Unix systems the one by Heroku and Scott Baker are best. Here are the steps required:

Check that openssl is installed by running the following command in a terminal:
which openssl
If no such file is found then you need to install. Here are the possible installation methods
1. Mac OSX – Via Homebrew: homebrew install openssl
2. Windows – Download software package.
3. Linux (Debian/Ubuntu Variants) – Guide – sudo apt-get install openssl
4. Linux (RedHat Variants) – Guide – yum install openssl
Generate the keys for the Certificate Authority
openssl genrsa -des3 -out ca.key 4096
openssl req -new -x509 -days 3650 -key ca.key -out ca.crt
Generate the private key for your server
openssl genrsa -des3 -out server.key 4096
Create the certificate signing request to be signed (leave challenge password and organization name empty)
openssl req -new -key server.key -out server.csr
Sign your certificate
openssl x509 -req -days 3650 -in server.csr -CA ca.crt -CAkey ca.key -set_serial 01 -out server.crt
Optionally remove the password
openssl rsa -in server.key -out server.key.nopass

For some documentation about how to use openssl check the official site.

Subtypes or Roles for parties

Posted on 2012-02-10 by Frankie

Recently I participated in a discussion of a common problem in data modelling. The question is whether to represent parties (groups) as roles or as subtypes (generalisation hierarchy).

When designing the Conceptual Data Model, parties can be represented as subtypes provided there is a common context amongst sub-types. In the Logical Model, subtypes should be represented only if each subtype has a unique concept that the others don’t.

You can read view the LinkedIn discussion here and/or see my Short notes on Barker’s ERD Notation.