Well, the first version of PownceFS didn't turn out as well as I had hoped. After I put it out in the world, Leonard ran with it and very nearly got everything to behave on a Mac. But even with his help I still hadn't been able to import songs my friends had uploaded to Pownce directly into iTunes.
That was March, this is June. A couple of nights ago I got PownceFS working well on Leopard. Things aren't all well quite yet but it's much closer. I can mount the filesystem by running ./powncefs.py mnt, and it'll show up in Finder just like I'd hoped but there the quirks begin. Finder is rather fickle about what system calls it actually issues, so I'm trying to figure out how to guarantee the directory entries are present. Thus far, the most foolproof way is simply running ls -lR after mounting the filesystem. (Less than fast.) Assuming Finder plays nice, the iTunes import will step in and be mean to you. For some unknown reason the script dies during the iTunes import (with the copy-to-iTunes-folder bit set). I've got to instrument the code a bit to see what's really happening but that is for another day.
This blog post isn't really a release, per se, just getting something more out there for other folks to hack on. Here we go now: PownceFS on GitHub
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The magical code push finally happened! Time to send PownceFS into the Internet. PownceFS is a Fuse filesystem that mounts your friends' files from Pownce as a local filesystem. Given a mountpoint, it fakes a directory for each of your friends and puts all the files they've uploaded inside. Files are cached locally for a while so you can repeatedly access things without spending your life waiting on yet another API call.
I can ls -l Mike Malone now!
rcrowley@banzai:~/powncefs$ ./powncefs.py mnt
rcrowley@banzai:~/powncefs$ ls -l mnt/
total 0
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 ajvchuk
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 andreiz
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 Andrew
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 chaddickerson
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 cowsandmilk
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 eston
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 evilcindy
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 flawedartist
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 halletecco
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 iamcal
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 ianloic
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 karaemurphy
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 katherinerose1224
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 katiejane
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 laughingsquid
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 leahculver
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 mmalone
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 philfreo
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 phil_halley
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 rcrowley
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 tychay
dr-xr-xr-x 2 rcrowley users 0 1969-12-31 16:00 waferbaby
rcrowley@banzai:~/powncefs$ ls -l mnt/mmalone/
total 41429
-r--r--r-- 1 rcrowley users 59381 1969-12-31 16:00 loveletter.jpg
-r--r--r-- 1 rcrowley users 291326 1969-12-31 16:00 mule.png
-r--r--r-- 1 rcrowley users 3830 1969-12-31 16:00 powncer.zip
-r--r--r-- 1 rcrowley users 75202 1969-12-31 16:00 sxsw_badge.jpg
-r--r--r-- 1 rcrowley users 41992791 1969-12-31 16:00 TWiT0134H.mp3
rcrowley@banzai:~/powncefs$ fusermount -u mnt
rcrowley@banzai:~/powncefs$
How can I get some, too?
On Linux it's simply a matter of installing Fuse, python-fuse and the Python OAuth library.
$ sudo apt-get install python-fuse
$ cd /usr/lib/python2.5/site-packages/
$ sudo svn co http://oauth.googlecode.com/svn/code/python/oauth
On a Mac I think it's pretty easy but my Python's wonky. Methinks the dependencies work themselves out — can someone verify?
$ sudo port install fuse-bindings-python
$ cd <wherever the hell Python is>
$ sudo svn co http://oauth.googlecode.com/svn/code/python/oauth
powncefs-0.1.tar.bz2 or http://svn.rcrowley.org/svn/powncefs/ PownceFS on GitHub
Nerd out with me
The "architecture" (if you can really call something with 2 files an architecture) goes something like this: when you run the script a
PownceFS object is created. The first thing it does is authenticate with Pownce and pull down your friends list to create it's directory structure. Whenever necessary it makes an additional API call to Pownce to fetch the list of files for a particular user (say, if you
ls their directory). API calls and files are cached for 45 minutes (safely under the one hour TTL of the S3 URLs returned by the API).
The root of the filesystem is a PownceFS.Base object that contains a dictionary of usernames to PownceFS.User objects. Each PownceFS.User contains a dictionary of filenames to PownceFS.File objects (look, Ma, inheritance!).
The main PownceFS object implements system call equivalents like getattr and readdir but defers the thinking to the tree of PownceFS.Base and friends. Each of those objects has a getattr function handling all of the filesystem bookkeeping, get and put methods for manipulating children and a fetch method for performing any API calls that need to happen. PownceFS.Files have an additional read method that reads the locally-cached copy of its file.
The point of that long-winded explanation is that the "architecture" is useful for absolutely any web service that might be a useful filesystem. The api.py file handles all of the OAuth-y stuff and leaves powncefs.py fairly generic. Hack!
Again, http://svn.rcrowley.org/svn/powncefs/ PownceFS on GitHub.
Future plans
The most obvious enhancement is to allow file uploads, which I'm planning on adding soon. Otherwise I need to find a few minutes to loop the API calls to return more than 100 files for those Power Users. Details, details.
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