[nm-wg] Specifying units

[Loukik Kudarimoti]

Hello Gang,

It has come to our notice that the messages in v2 responses do not 
specify units while giving back measurement data (ex: Bandwidth 
Utilization and Capacity). Specifying such units is necessary and 
messages should be enhanced to support this.

Also, there is scope for optimization in such specification. For 
example, while returning back data

instead of

<perfsonar:datum timeValue="1127183580" value="7.620117028888889E7" 
units ="bps"/>
<perfsonar:datum timeValue="1127183640" value="1.4989345286805557E7" 
units ="bps"/>
<perfsonar:datum timeValue="1127183700" value="1.50811390446627E7" units 
="bps"/>

we could specify it just once..maybe like this:

<perfsonar:data dataUnits="bps">
    <perfsonar:datum timeValue="1127183580" value="7.620117028888889E7"/>
    <perfsonar:datum timeValue="1127183640" value="1.4989345286805557E7"/>
    <perfsonar:datum timeValue="1127183700" value="1.50811390446627E7"/>
</perfsonar:data>

or like this:

<perfsonar:data>
<perfsonar:units dataUnits="bps"/>
    <perfsonar:datum timeValue="1127183580" value="7.620117028888889E7"/>
    <perfsonar:datum timeValue="1127183640" value="1.4989345286805557E7"/>
    <perfsonar:datum timeValue="1127183700" value="1.50811390446627E7"/>
</perfsonar:data>

or something else...

The second comment is: Choice of units.

After a chat with Jeff on this, I can list out two options

Jeff suggested that: Service uses the units that the data is already in 
(for ex. in rrd tool, data is in octets per second. Hence service 
continues to provide data in octets per second) and continues to return 
data in the same units. However, the units in use should be clearly 
specified using any of the above suitable methods.

An option that I would like to propose is usage of units used in common 
practice. For example, bandwidth, as known to me, is more commonly 
expressed in bps (and their factors).  A service should hence 
*reasonably* strive to use the units that are in common practice. Either 
way, specification of units using any of the suitable methods mentioned 
previously is absolutely necessary.

However, it can be remarked that 'bps' is not necessarily common. 
Netflow measurements might prefer to use something else which are in 
common practice in the netflow domain. In such cases, specification of 
units should suffice.

Nevertheless, if a service returns capacity and utilization in the same 
message, it would be nice to have them both in the same units (unlike 
the current case with Perfsonar prototype where capacity is bps and 
utilization is octets per second)

Question here is: Which option is ideal? Should we provide capacity and 
utilization in the same units in our prototype?

Loukik.





       

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______________________________________________________________________

Loukik Kudarimoti
Network Engineer

DANTE - www.dante.net

Tel: +44 (0)1223 371 300
Fax: +44 (0)1223 371 371
Email: loukik.kudarimoti at dante.org.uk

City House, 126-130 Hills Road
Cambridge CB2 1PQ
UK
_____________________________________________________________________