When working on Telepathy, I've often wanted to be see which D-Bus methods are being called on whom, when signals are emitted, and so on. Timing information is also handy: I'd like to figure out why cold-starting Empathy takes 12 seconds, and it'd be much easier if I could look at a diagram rather than staring at the unreadable output of dbus-monitor.
Previously, Alban wrote a tool that used a patched version of mscgen, and produced appropriate input with a dbus-monitor-like Python script. I wanted some more D-Bus-specific diagrams, and ended up reimplementing both the monitoring component (by forking dbus-monitor, as its --profile output did not contain quite enough information) and the diagram-drawing component (using Cairo). I'm happy to present an initial release of Bustle:
There's a Telepathy-specific hack in the tool to shorten object paths, but it shouldn't make the tool any less useful for looking at other D-Bus traffic.
I haven't made binary packages yet, I'm afraid, so you'll need to grab the source tarball and build it if you want to try it out. In Debian-land, the dependencies are libdbus-1-dev libglib2.0-dev libghc6-mtl-dev libghc6-cairo-dev libghc6-gtk-dev libghc6-parsec-dev; see README in the source tree for how to build and use it.
The astute among you may have noticed from the dependencies that the diagram-building component is implemented in Haskell, using the excellent bindings to Gtk+ and Cairo. I got a prototype going within a few hours, and the strong correctness guarantees that the type system provides meant that I could refactor it mercilessly with confidence. I'm sure that I would have spent many frustrating hours chasing type bugs had I written it in Python, which is a more conventional high-level language for prototyping and writing tools like this. Next time you're frustrated by such bugs, you should give Haskell a try. :-)
Edit: Bustle now lives at willthompson.co.uk/bustle.