C++, Qt and Treefrog to build user facing web applications
In the past I have written about my usage of Tufao and Qt to build REST services. This time I am writing about my experience of using the TreeFrog framework to build a full web application.
You might wonder why one would want to build such a thing in a statically and compiled language instead of something more dynamic. There are a few reasons for it:
- Performance: The application is intended to run on our sysmoBTS GSM Basestation (TI Davinci DM644x). By modern standards it is a very low-end SoC (ARMv5te instruction set, single core, etc, low amount of RAM) and at the same time still perfectly fine to run a GSM network.
- Interface: For GSM we have various libraries with a C programming interface and they are easy to consume from C++.
- Compilation/Distribution: By (cross-)building the application there is a “single” executable and we don’t have the dependency mess of Ruby.
The second decision was to not use Tufao and search for a framework that has user management and a template/rendering/canvas engine built-in. At the Chaos Computer Camp in 2007 I remember to have heard a conversation of “Qt” for the Web (Wt, C++ Web Toolkit) and this was the first framework I looked at. It seems like a fine project/product but interfacing with Qt seemed like an after thought. I continued to look and ended up finding and trying the TreeFrog framework.
I am really surprised how long this project exists without having heard about it. It is using/built on top of Qt, uses QtSQL for the ORM mapping, QMetaObject for dispatching to controllers and the template engine and resembles Ruby on Rails a lot. It has two template engines, routing of URLs to controllers/slots, one can embed any C++ in the template. The documentation is complete and by using the search on the website I found everything I was searching for my “advanced” topics. Because of my own stupidity I ended up single stepping through the code and a Qt coder should feel right at home.
My favorite features:
- tspawn model TableName will autogenerate (and update) a C++ model based on the table in the database. The updating is working as well.
- The application builds a libmodel.so, libhelper.so (I removed that) and libcontroller.so. When using the -r option of the application the application will respawn itself. At first I thought I would not like it but it improves round trip times.
- C++ in the template. The ERB template is parsed and a C++ class will be generated and the ::toString() method will generate the HTML code. So in case something is going wrong, it is very easy to inspect.
If you are currently using Ruby on Rails, Django but would like to do it with C++, have a look at TreeFrog. I really like it so far.