[Babel-users] babeld interface

[Christof Schulze]

>> 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.
>
>Please let me know if you disagree, I'm not fundamentally opposed to
>adding a new command "monitor-json" if you think it's desirable, but I'd
>rather avoid the added complexity.
I agree that the current format is very easy to parse for a human, which 
is a benefit. I am struggling to have a machine parse this though.

Just from the switch for babeld-1.8.0 to master a new field got 
introduced for neighbour lines. This caused my sscanf-based line-parser 
to break:

int n = sscanf(line, "%ms neighbour %*x address %ms if %ms "
		"reach %x ureach %*x rxcost %d txcost %d cost %d",
		&action, &address_str, &ifname, &reach, &rxcost, &txcost, &cost);

The whole code for the parsing is in a library that lives here: https://github.com/christf/libbabelhelper

Maybe I am just not parsing this the easy but the hard way. So 
before going into the benefits of json, maybe we can see if there is a 
manufactoring error with my own approach in parsing this.

So instead of running sscanf like above, I guess I could strtok the line 
and just match for known keywords and extract their values, however 
blanks in values would be a problem to this approach. Do we really need 
to deal with blanks in values?

Christof


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