Over the years CanalPlanAC has accumulated a host of data formats for various purposes. At least two – a custom C-like syntax (surprisingly similar to another I’ve adopted!) and “quick load” place and link files – are entirely obsolete but support for them still lurks in the interpreter.
Here are the main ones that anyone playing with the system might come across:
- SQL – since summer 2008 the main database for CanalPlanAC, the users, the information about photographs, some of the program flow control and state information during a session have been stored in SQL databases. I’m using SQLite – this is small and can be directly integrated into the interpreter making setup very easy.
- XML – until then XML was used for the master data file, and quick-read varieties in a sort of unstructured text file were generated. The unstructured files are also obsolete (although some support may still exist in route.c until I rip it out) but XML is still used although much more round the edges these days. In particular, it’s used for:
- Storing the configuration file /cgi-bin/config.xml which tells the program where all the data should be stored and similar things
- To store the default user options in a file, and the user options (in a blob) in the user SQL database
- To define options for gazetteer plugins (to be described some other time!)
- HTML – static pages are written in HTML
- CST – ClearSilver Templates. Since summer 2007 pages are generated from template files. This is an extended form of HTML with ClearSilver directives built into it – see the website for more.
- HDF – this is the configuration file language for ClearSilver. I didn’t have to use this, I’ve integrated ClearSilver so tightly I can easily pass it any format I like, but it seemed sensible. The most important HDF file is /templates/default/config.hdf which controls all the menus and buttons on all the pages.
So there you are. A pile of formats, but many of them widely known, and many of them only used in a few places. In the next few articles I’ll show how to add a sophisticated new feature (the Virtual Cruise) to CanalPlanAC and you’ll see how these various languages and formats are used.