Yesterday we released Avahi 0.2. Get it while it is hot! Full announcement here.

In related news: Jakub Stachowski is working on a kdnssd-to-Avahi bridge. Soon KDE applications will be able to make use of Avahi without even knowing.

Sebastien's Zeroconf Gnome Applet now has an SVN repository: svn checkout svn://svn.0pointer.de/service-discovery-applet/trunk service-discovery-applet.

Sebastien successfully completed porting GnomeMeeting to Avahi. Therefore I declare him the first one to port a "real world" application to Avahi. Hurrah! Screenshot here.

Shortly after, Sebestien - not lazy - announced his new Zeroconf service browser applet based on Avahi. It contains a drop down menu with all Zeroconf services found on your LAN. If you select a menu item the applet will execute the application that has been defined as Gnome URL handler for the specific protocol.

Seems today's edition of LWN features a front page story about Avahi. It's actually quite nice, even though I missed an emphasis on the fact that Avahi's mDNS stack itself is embeddable into applications via a shared library.

I guess you'll have to wait a week if you want to read the article without subscription.

We finally released Avahi 0.1. Full release announcement here. Avahi comes with a powerful DBUS API. Just two show off the coolnes of that interface a Python example:

import avahi, dbus, gobject

bus = dbus.SystemBus()
server = dbus.Interface(bus.get_object(avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER), avahi.DBUS_INTERFACE_SERVER)

def new_service(interface, protocol, name, type, domain):
	print "Found service '%s' of type '%s' in domain '%s'" % (name, type, domain)

def remove_service(interface, protocol, name, type, domain):
	print "Service '%s' of type '%s' in domain '%s' disappeared." % (name, type, domain)

path = server.ServiceBrowserNew(avahi.IF_UNSPEC, avahi.PROTO_UNSPEC, "_http._tcp", "")
b = dbus.Interface(bus.get_object(avahi.DBUS_NAME, path), avahi.DBUS_INTERFACE_SERVICE_BROWSER)
b.connect_to_signal('ItemNew', new_service)
b.connect_to_signal('ItemRemove', remove_service)
gobject.MainLoop().run()

This short program will connect to running avahi-daemon and browse for web services.

The pyblosxom plugin registry links a plugin which allows hiding "draft" stories before publishing them, so that only you can see them. Unfortunately the link to this plugin is broken. So here's my (simplified) reimplementation:

def cb_prepare(args):
        request = args["request"]
        query = request.getHttp().get('QUERY_STRING', '')

        if not query.endswith("&ignore") and not query == "ignore":
                data = request.getData()
                data["entry_list"] = filter(lambda e: not e.has_key('ignore'), data["entry_list"])

To mark a story as "draft" simply insert this at line #2:

#ignore yes

To browse unpublished stories simply append ?ignore (or &ignore) to your blog URL.

If you run a pyblosxom blog with auto-copied stories from SVN you are probably interested in getting stable story dates that don't change every time you update a story. The date of the initial SVN log entry of a story is something like the "day of birth" of a story, so it's a good value to use. Christopher Baus implemented a plugin for pyblosxom, which looks overly complicated to me: it depends on memcached and comes in two large python scripts.

To simplify things I wrote this minimal replacement:

import pysvn, os, sys, anydbm

from config import py

def get_mtime(fname):
        cache_fname = os.path.join(py['datadir'], 'SVNDATES')
        cache = anydbm.open(cache_fname, "c")

        if cache.has_key(fname):
                d = float(cache[fname])
        else:
                client = pysvn.Client(fname)
                l = client.log(fname)

                if len(l) > 0:
                        d = l[0]['date']
                        cache[fname] = str(d)
                else:
                        d = -1

                del client

        del cache
        return d

def cb_filestat(args):
        args["mtime"] = list(args["mtime"])
        d = get_mtime(args["filename"])
        if d >= 0:
                args["mtime"][8] = d
        return args

Since accessing SVN logs is quite slow the script caches the "date of birth" in a dbm file. Make sure that your web server has enough priviliges to access that database file which is stored in $datadir/SVNDATES by default.

Avahi 0.1 is due in the next few days. The last missing piece is a simplifying C wrapper around the DBUS API. Though Avahi is currently pre-0.1 it is already quite complete and mature. To put it with Ross Burton: "... this doesnt count as 0.1 because it has docs, man pages *and* works"

Unfortunately python-dbus has quite a few bugs which make it very difficult to code with. e.g. it doesn't handle sending empty arrays, fails to send byte values and so on. It is difficult to work around all these issues, therefore the Avahi client tools will not work with an unpatched python-dbus. You need to apply this patch (applying to 0.35.2) to fix at least the byte value bug to get them working.