24/07/2013

* Between the drawer and the cupboard




Between the drawer and the cupboard
A top manager who is not IT saavy asked me to explain in simple layman language the difference between a desktop GIS and a relational database management system (RDBMS) server. I was caught off guard because I was so familiar with it that I was stumbling hard how to analogue the topic. I put on my thinking hat and thought how best to present the case. My friend offered an analogue approach and choose the task of moving from a slum to a proper house while I preferred to demonstrate by showing the difference in keeping things in a drawer and a cupboard. In a drawer, there is a tendency to dump anything or everything in it although it is possible to keep things neat and tidy. However, GIS data is often voluminous, something inappropriate to be kept in a drawer. Thus if many things were kept in a drawer to the brim, it will be difficult o manage. However, if all the items were transferred to a cupboard it would be comparatively much easier to store, manage, search, find and retrieve specific items because not only is the cupboard larger but also most cupboard have a few drawers and other odd spaces to accommodate items of different size. Thus the cupboard represents the desktop GIS while the cupboard represents the RDBMS server. I wanted to go further to elaborate (but am hesistant) how data kept in a desktop GIS is fundamentally kept in a table of rows and columns known as an Attribute Table but that situations which involve one-to-many could not be accommodated into that Attribute Table unless it was linked to a personal database system like Microsoft's Access or OpenOffice.org's Database alternatively to a spreadsheet like Microsoft Excel or OpenOffice.org's Calc. So for the time being, I'm going to leave it as such.

01/07/2013

Downgrading Ubuntu QGIS 1.9 to QGIS 1.8

Force version used here
QGIS 1.8 successfully installed but expect another surprise
Broken packages need prerequisite repair
Don't expect any success until QGIS repositories have been removed
Downgrading Ubuntu QGIS 1.9 to QGIS 1.8

Today, after frustrated not being able to activate Google Maps in QGIS 1.9, I decided to downgrade to QGIS 1.8. It was a trying experience because I'm not an IT man and eventhough I had removed QGIS's 1.9 brain and heart, it was still around under Synaptic Package Manager, still hanging around like a zombie and until I got rid of that, it was an impossible task. However, I eventually managed to downgrade QGIS 1.9 and install QGIS 1.8. If you are not interested, go no further but if you are, read on but there is a surprise at the ending which I need to give it another try at home to confirm it again coz all this is being done on my office computer. It was a long exercise of trial and error. At first, I used the Synaptic Package Manager not to 'uninstall' but to downgrade by 'Force Version'. However, it appeared that there were broken package which even after successfully repairing the broken packages, QGIS 1.8 refused to install because of broken packages which still seem to be around. I decided to go terminal mode and type "sudo apt-get purge qgis 1.9". Not good, so next I typed "sudo apt-get --purge autoremove". Not good so this time I dissected the file manager and making hidden files visible, deleted the QGIS folder under Home as well as the .gqis folder under .config folder. QGIS 1.9 still refused to go. This was madness. It appeared the spiritual umbilical cord was still around and it was not until I removed the repository links under System Setting could I install QGIS 1.8. The irony now was that after QGIS 1.8 got installed, 'Fetch Python Plugin' was not available. So I updated patch files by typing "sudo apt-get update" but results were not good. Un-installation and re-installation of QGIS under Ubuntu Software Centre also did not produce any fruitful results. Well, it's back to the drawing board for me but this time on QGIS 1.8. So far, I understand that when a new version of Ubuntu comes along, if you want the Python Plugins to work, QGIS developers must have ensured that the Python Plugin Repository is compatible with the new Ubuntu version or else QGIS is face these plugin hiccups because the Plugin repository installer does not work. So if a certain plugin is critical for the user, that user cannot follow the whims, fancy and progress of the Ubuntu operating system but must adhere to which version QGIS is compatible to which Ubuntu OS version.


Howard (see below under Comments) thankfully recommended going here for a OpenLayers fix. However, it is a hacker's approach and unless you know how to enter hidden files I do not recommend it. Even so, your computer file structure need to be the same as recommended for eg. I have a .qgis folder not a .qgis2 folder as reuired furthermore in my .qgis folder, python folder does not exit.

My son who is studying computer science and keen on open source software told me that when one upgrades an operating system by online upgrade such as what I did, there is a possibility of certain drivers required by certain applications could be missing causing certain modules refusing to work whereas when the operating system was installed via a CD installer, there chances of such missing files happening are slim. He advised me to reinstall my Ubuntu 13.04 using a Cd installer to fill up any missing files that could have been which I am in the processing of downloading an iso file. So when QGIS gives problem, one must ask in the first place whether the operating system had acquired all the necessary files and drives for various types of applications desired to be installed? If that was the case, one can then ask the second question that is when an application upgrades itself, whether all the plugins found in the previous version had been upgraded accordingly by the various developers? It was mentioned in the Internet that at QGIS, the concern is concentrating on coming up with a comprehensive and workable QGIS 2.0 and with a dateline to catch but with limited manpower and financial resources, one must not be too fussy, after all this is Open Source.