[Babel-users] babeld interface

[Toke Høiland-Jørgensen]

Juliusz Chroboczek <jch at irif.fr> writes:

>> Nils and I wrote such a daemon, called mmfd. It is able to forward
>> multicast packets in the whole network. To learn about the topology and
>> the relevant neighbours, it queries babeld: mmfd is listening via
>> "monitor" on the babeld socket.
>
> Good.
>
>> What do you think of providing the same data over json to make it better
>> parsable?
>
> The format of the monitoring interface is well defined : it's a series of
> lines of the form
>
>   keyword id key value key value ...
>
> where each key/value is either space separated, or a string within double
> quotes.
>
> This format is extensible (we can add new keywords and new keys at any
> time), and it's also easy to parse by a human (Antonin and I have just
> spent much of today telnetting by hand into Babel's monitoring
> interface). So I'm not convinced that switching to JSON would have any
> benefits.

The main benefit of a well-known format is that the requirement for a
client goes from easy parsing code to *no* parsing code.

In this example, parsing the custom format in Python would be something
like:

data = {}
for line in input:
  keyword, id, rest = line.split(" ", 3)
  data[keyword] = {'id': id}
  parts = rest.split(" ") # wait, this doesn't deal with quoted values
  for key, val in zip(parts[::2], parts[1::2]):
    data[keyword][key] = val

vs

data = json.loads(input)

Also, if you pretty-print the json it is quite human-readable; try e.g.
`cat datafile.json | python -m json.tool`

-Toke