Daniel Nicoletti

Brazil, São Paulo http://dantti.wordpress.com 25 Posts

Cutelyst a Qt web framework

Do you recall that "Qt everywhere" branding?

Well that's one of the things I really like in Qt, being able to deploy everywhere with minimal to zero changes in source code. But sometimes your application needs a web interface some sort of web backend or web admin, and when that happens it breaks that slogan (AFAIK)...

I got in contact with web languages (not HTML) only when at university, ColdFusion and PHP where the first ones, and while PHP was sort of cool because it has a syntax close to C, I never really like it. I'm not a web designer nor know how to do pretty websites, but in today's world building web apps is inevitable.

So years ago I learned about RubyOnRails, and people where talking all the good stuff about it, it's was the framework of the hype, although I knew Ruby wasn't the fastest scripted language my need didn't demand that, so I got a book, read it cover to cover and happily started my web app, a week latter I got a complex problem with an apparently impossible solution. It seemed that RoR makes easy things stupidly easy and complex things impossible...

The I met Catalyst a Perl framework, got exited again, but I knew nothing about Perl so I read more 3 books and was started to love the language, I still do, but last weekend when trying to resurrect and old Catalyst application I got an error which I had no idea how to fix, on IRC I was told the problem could be that I mixed CPAN packages with distro packages, not very convinced I realized the bigger problem I was actually facing, I'm not fluent in Perl, well no matter how many books you read about a language you only get fluency in it after speaking it almost everyday, this applies to computing languages too of course.

So if 99% of the time (or less now with QML) I'm programming C++ it means that I know a lot more about how to debug it than with Perl, so Cutelyst! Writting web apps in Qt/C++ will be much more efficient to me and hopefully to you too.

I share lots of the Catalyst API and design ideas, tho the implementation is of course completely different. Also for the sake of HTML templating I plan to create a Grantlee View plugin.

You can take a look at the proof of concept:

https://gitorious.org/cutelyst

Have fun.

Cutelyst the Qt/C++ Web Framework just got it's first version released!

Three months ago Custelyst was started, it was somehow a proof of concept to see if I could build something that could be used in the real world, but the more I progressed on getting all the pieces together the happier with the overall result I got. And the initial result is here today! I have made a few benchmarks comparing some simple pages delivery using Django (python) and Perl Catalyst, and overall the time to first byte was around 3 times faster than both, comparing RAM usage it was like 2MB vs 50MB from the Perl version and 20MB of the Python one, the CPU time was also much smaller if compared to both which probably means it could handle more requests, but this isn't a completely fair benchmark (as always) because there are several other things to measure... Below I'll try to clarify some doubts raised from my last post and what makes this new Web Framework unique:

But there is already QDjango and Tufao...

I didn't know about these ones when I first started Cutelyst, but after taking a look at them, both misses a templating system (or integration with one), I also didn't like the way one would register actions to be dispatched, IMO the way it's done in Cutelyst is easier and nicer. And they doesn't count with WSGI integration, they have their own HTTP parser/server. I also didn't like looking at code :P

Why not DJango or any other well established framework out there?....

Apart from QDjango and Tufao there are no other (AFAIK) Qt based frameworks, there are indeed some C++ ones that I knew before but I didn't like the way of doing things there, in fact when I started with Perl Catalyst I really liked how it was written. So in short I don't know well enough other languages and I have no plans wasting my time learning other languages, I'd rather try to master at least one (although I know I'm far from it).

What's in this release?

  • Glad you asked (duh!)
  • Production ready integration with uWSGI, meaning Cutelyst has a uWSGI plugin that will load your application (which will also be a plugin), and thus thanks to uWSGI it will have out of the box support for FastCGI, HTTP(s), uWSGI (protocol) and probably some other.
  • ClearSilver templates integration, this templating system is written in C and it's amazingly fast, but it's also incredible limited to what you can do in the view.
  • Grantlee (Django) templates integration, it's used in KDE PIM to allow for easy templating of HTML, it's slower than ClearSilver but offers much more fexibilities on your views, and since it's also written in Qt the introspection comes for free.
  • Complete Path dispatcher, which means if you Port a Perl Catalyst Application that was using Path actions it will work as expected. This dispatcher matches an url to a Q_INVOKABLE method depending on it's signature, The Catalyst Chained dispatcher is not implemented yet.
  • Session plugin, easy to use way of persisting data across requests, right now it's done with a QSettings file, but integration with Redis and MongoDB are planned.
  • Authentication plugin, allowing you to authenticate your users using different Realms/stores, currently a StoreMinimal is implemented which can be used mostly for testing purposes (ie on the code you add your users)
  • StaticSimple plugin, allows for serving static content reducing the complexity of serving static content while developing your app.

If you are concerned about API/ABI stability I don't promise it just right now it's almost stable, probably 0.2 or 0.3 versions will have a promised stable API. And yes, I have just put it on production http://serial.igloobox.com.br is running it right now (but the site is user restricted). My plans now is to setup cutelyst.org with docs and examples, as well as writing a web blog, bug tracker and wiki based on it.

Have fun!

Download

Cutelyst 0.2.0 is out!

Five months ago I announced the very first release of Cutelyst, a web framework powered by Qt 5. Time passes and I started shaping my real world applications written with it, I should probably release a newer version earlier but it's not very nice to keep releasing API that changes a lot, however next version (0.3.0) will still contains API changes. What changed from 0.1.0 to 0.2.0:

  • I have setup a documentation website http://cutelyst.org
  • I started a WordPress like blog written with Cutelyst https://gitorious.org/cutelyst/untitled this right now is a nice example app, if you like it please help :)
  • Changed the API to expose the forked behavior thus being able to setup database connection in each new process avoiding a mess
  • UWSGI got a patch to deal with workers that don't want to work, in other words when something on post-fork fails like reaching the dababase connection limit the worker can exit and won't be restarted.
  • A bunch of bugfixed of course
  • Make use of categorized logging (ie qCDebug)
  • Allow for UWSGI to restart the application as soon as your application .so file changes, this greatly improve development speed :)
  • Encapsulated the post body into a QIODevice subclass on UWSGI engine this means a QFile is --post-buffering limit is reached, or a custom IODevice that deals with the request memory buffer
  • A parser to get uploaded content "multipart/form-data" which is fast and can work with lots of data

For the next version I'll try to get a properQt loop integration.

Download here

Have fun!

Cutelyst 0.3.0 is now C10K ready!

Release early, release often has never been my strength especially since I don't do a fair scheduling of all the projects I'm involved...

So since I was in need to better polish Cutelyst I took more time on it, and the result is great, around 100% speed up and a few new features added.

Cutelyst uWSGI plugin now has support for --thread, which will create a QThread to process a request, however I strongly discourage its usage in Cutelyst, the performance is ~7% inferior and a crash in your code will break other requests, and as of now ASYNC mode is not supported in threaded mode due to a limitation in uWSGI request queue.

Thanks to valgrind I managed to make a hello world application from 5K request per second on 0.2.0 to 10K req/s on 0.3.0 on an Intel Core2Duo 2.4Ghz (or 44K req/s on an AMD Phenom II 965 x4 3.4Ghz), however if you enable Grantlee templating you get around 600 req/s so if I happen to have time I will be looking into improving its performance.

Response::body() is now a QIODevice so you can set a QFile* of something else and have Cutelyst to send it back.

Now http://cutelyst.org points to a gitorious Wiki which is slowly getting populated, and API is available as http://api.cutelyst.org.

The 0.3.0 tarball can be downloaded here

Have fun :)

Cutelyst 0.5.0

A bit more than one year after the initial commit, Cutelyst makes it's 5th release. It's now powering 3 commercial applications, the last one recently got into production and is the most complex of them, making heavy use of Grantlee and Cutelyst capabilities. Speaking of Grantlee if you use it on Qt5 you will get hit by QTBUG-41469 which sadly doesn't seems to get fixed in time for 5.4, but uWSGI can constrain your application resources so your server doesn't go out of memory (worth the leak due to it's usefulness). Here is an overview since 0.4.0 release:

  • Remove hardcode build setting to "Debug", so that one can build with "Release" increasing performance up to 20% - https://gitorious.org/cutelyst/pages/CutelystPerformance
  • Request::uploads() API was changed to be useful in real world, filling a QMap with the form field name as a key and in the proper order sent by the client
  • Introduced a new C_ATTR macro which allows to have the same Perl attributs syntax like C_ATTR(method_name, :Path(/foo/bar) :Args)
  • Added an Action class RoleACL which allows for doing authorization on control lists, making it easy to deny access to some resources if a user doesn't match the needed role
  • Added a RenderView class to make it easier to delegate the rendering to a view such as Grantlee
  • Request class is now QObject class so that we can use it on Grantlee as ctx.request.something
  • Make use of uWSGI ini (--init) configuration file to also configure the Cutelyst application
  • Better docs
  • As always some bugs were fixed

I'm very happy with the results, all those site performance tools like webpagetest give great scores for the apps, and I have started to work on translating Catalyst tutorial to Cutelyst, but I realize that I need Chained dispatcher working before that... If you want to try it, I've made a hello-world app available today at https://gitorious.org/cutelyst/hello-world Download here!