[Qgis-developer] Software & Data Engineering and Modelling

Alex Mandel tech_dev at wildintellect.com
Thu Apr 18 14:21:54 PDT 2013

On 04/18/2013 10:44 AM, Petros Apotsos wrote:
> Dear Matthias and list members,
> According to my POV, documentation is of fundamental importance to software
> development!
> I have sent messages to this list at least 2 times in the past, regarding
> aspects of this particular subject. The responses I got: 0!!!
> What I have learned in my Postgraduate Studies is that BEFORE, but also
> WHILE developing a Software Project (like QGIS) or a Database (like a GIS)
> it is essential to build a conceptual model of the system. This should be
> done both on static and functional basis.
> My immediate concern at this time is the model of Geometric Networks. I want
> to build some fleet tracking tools that use sequential GPS signals to
> calculate vehicle passes through points, trajectories, routing etc. So, I
> started modelling the QGIS library classes that I thought were relevant to
> my subject. This is an ongoing work, and I have modelled a few classes,
> their relationships, but also some use cases and functions. I am using UML
> notation for this task.
> Note, that I am not using UML to automatically produce code. This is a
> misconception, I think, of UML and its purpose in developing systems. I use
> modeling purely for overview and documentation reasons, as I am not a
> hard-core coder, but rather a GIS designer/engineer.
> These being said, I think this modeling process can help with various issues
> of QGIS development, including (but not limited to):
> - Layers and sublayers programmatical handling
> - Grouping and programmatical access of tools like SEXTANTE (and also other
> plugins)
> - API documentation (not the automatic one, but rather a manually updated
> one, addressing all relevant issues to specific classes and methods).
> - Connection between classes of different libraries (GDAL, QGIS, Qt etc.)
> I hope that was a neat introduction to my thoughts about how GIS systems
> should be documented! I also REALLY hope it gets some attention this time!
> IF any of you think we can do some introductory work on QGIS documentation
> (be it the actual API, GUI elements or any other part of the project) using
> modern UML annotation and tools, please feel free to contact me with details
> and ideas. I am willing to volunteer a few hours each week towards making
> the QGIS project better, and documentation is the first step.
> I am also open to conversations on this subject (a blog/forum would be
> REALLY helpful there) and opinion sharing.
> Hoping this message will strike some strings,
> Petros Apotsos


Can you share some example diagrams you've made already and explain how 
they could integrate with the QGIS API and it's auto diagrams. I don't 
think anyone opposes your ideas but it's something you're going to have 
to get started and see if others want to help/continue the method.

Obviously we can host/incorporate such diagrams into the existing 

Keep in mind there is a learning curve to UML and tools for UML, so 
simplification and recommendations are helpful there.


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