[zeromq-dev] Statistics protocol v0.1

Gregg Irwin gregg at pointillistic.com
Thu Jun 7 00:33:46 CEST 2012


Hi Paul,

PC> I don't know what you mean by "model". For rrd "counter" type is
PC> basically a growing counter sent each time (e.g. messages passed
PC> through a gateway). rrdtool subtracts previous value from the current
PC> value to know rate (messages per second), and stores that rate. Its
PC> very convenient way to count several kinds of statistics.

Right, that's what I meant by coupling and model, rather than having
the protocol simply define the exchange format, it also covers
semantics.

PC> No, segments can't contain spaces. The colon is there to have a way to
PC> subscribe to whole value. E.g. subscribing to "example.org:cpu" will
PC> also hit "example.org:cpu0", which isn't what intended.

Your comments on the fields would be great to include in the docs.

PC> Having to subscribe to space-terminated topic is ugly. And there
PC> is a tab that is also a whitespace.

Allow any whitespace separator then.

>>  HOST is there for ...

PC> It's nice to know what host this statistics is for. Having monotonic
PC> sequence of dot-separated items, like in graphite/carbon
PC> "example.org.cpu" means we don't know where hostname ends. The host
PC> name is essential parameter to group data in a GUI.

OK. So this is another coupling, but could also be handled by
convention. I understand the reason, though, in your target context.

PC> I want to be able to have a path as a component in the name. e.g.:

PC> ESTP:example.org:disk:system/root:bytes_written:

PC> Where the "system/root" is lvm partition (/dev/system/root aka
PC> /dev/mapper/system-root).
PC> This is also the reason I've not used dot, like in graphite, as dot is
PC> used in hostnames.

Would a URI syntax work?

-- Gregg




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