July 2013 – saghul, on code

I’m happy to announce two new pyuv releases today: pyuv 0.10.5 (stable) and 0.11.0 (unstable). Why two releases? For those who may not know, pyuv follows the NodeJS release cycle, that is, odd numbered releases are the so called “unstable” releases, while the even numbered releases are “stable”.

The 0.10.5 release brings few bugfixes and embeds the latest version of libuv, so you also benefit from the bugfixes in libuv.

pyuv 0.11.0 includes some heavy refactoring of the filesystem operations, which unfortunately are not backwards compatible, but I hope it’s for the best:

In pyuv 0.10x this is the way to stat a file asynchronously:

def cb(loop, path, result, error):
    if error is None:
        print result
    # ...

pyuv.fs.stat(loop, 'test.py', callback=cb)

And here is the equivalent in pyuv 0.11:

def cb(req):
    if req.error is None:
        print result
    # ...

req = pyuv.fs.stat(loop, 'test.py', callback=cb)

All filesystem operations now get a single argument in the callback: the FSRequest object which was returned to the caller when the function was initially called. The loop, path, result and error are now attributes of the request object. Moreover, the request object now has an instance dictionary, so you can attach any attribute to it and use it later:

def cb(req):
    assert req.foo == 'foo'
    if req.error is None:
        print result
    # ...

req = pyuv.fs.stat(loop, 'test.py', callback=cb)
req.foo = 'foo'

There have been other big internal changes due to changes in libuv itself, but those are not visible in pyuv since it provides a class-level abstraction.

The next stable release will be pyuv 0.12.0, right when Node 0.12 is launched. Until then 0.10 will remain as the stable branch, and the one installable through PyPI, those of you interested in the latest and the greatest, go fetch master on GitHub 🙂

:wq

Long time no post! Lets solve that now shall we?

A few days ago I started playing a bit with Flask, since I’m considering it as the framework to build some API server. I have no web development experience, and Flask looks like a great project so I went with that.

I started with a tiny little hello world, and then I wanted to add some websockets and some CSS. Oh the trouble. When I started looking for how to combine a Flask app with WebSockets I found references to gevent-socketio for the most part, but I somewhat wanted to use Twisted this time, so I kept looking. Soon enough I found AutoBahn, a great WebSocket implementation for Twisted, which can be combined with a WSGI app, brilliant! After seeing how AutoBahn manages to add the websocket route to the WSGI app, adding support for static files was kind of trivial.

Here is the result of my experiments, a really simple web app which consists of a Flask WSGI app, a WebSocket server and some static files, all served by the same process running Twisted. You may not want to do this in a production environment, but hey, I’m just playing here 🙂

[gist]https://gist.github.com/saghul/5961882[/gist]

Since Gist does not currently allow folders, make sure you keep this layout after downloading the files:

├── app.py
├── settings.py
└── templates
    ├── assets
    │   └── style.css
    └── index.html

We’ll use the twistd command line tool to launch out application, since it can take care of logging, running as a daemon, etc. To run it in the foreground:

twistd -n -l - -y app.py

This will launch the application in non-daemon mode and log to standard output.

Hope this helps someone, all feedback is more than welcome 🙂

:wq

Month: July 2013

pyuv 0.10.5 (stable) and 0.11.0 (unstable) released!

Serving a WSGI app, WebSockets and static files with Twisted