psamp vocabulary

[Rae McLellan <rae@research.bell-labs.com>]

>> Invariance frees psamp from specifying the order and allows different
>> vendors to implement the selectors in different way w/o affecting the
>> results.
>
> that's exactly the point: it seems that "the results" for you means
> "the resulting selected sample".  With my comment above, I was saying
> that "the results" should be on the contrary
> "1) the size of the selected sample" and
>  2) the results you derive from the analysis of the selected sample".

I wish the results as you define them were all that mattered.  But in
a world of multi-vendor interoperability.  It so much easier to verify
that the report streams coming from two different vendor's boxes are
identical between different vender's boxes than the final analysis
being similar.  Indeed, vendor differentiation may well be in the
report analysis.

> Note that it's not only a terminology issue. If we require that varying
> the selector ordering (which is something that we may desire to ease
> implementations) we get the same selected sample, then we have to
> exclude the whole "third group" of samplers you outlined in your
> previous e-mail, i.e. random samplers and samplers based on packet
> position. To this last category belongs e.g. the simple 1 out of N
> sampler implemented by decrementing a counter, which is the simplest
> we can think of. Do we want to exclude it?

I realize it's a radical approach.  But, *if* the functionality (by your
definition of results) of the "third group" of random selectors can be
provided by deterministic hash functions on the packet header...
then yes, I'm suggesting the psamp standard exclude the "third group"
of random selectors.  I'm transferring effort in the standardization
process from specifying the order of selectors and worrying about
their grouping syntax/semantics, to a few short paragraphs explaining
how the deterministic hash functions can provide similar results.

Is this possible?  I dunno.  I was just pointing out that this might
be a path for psamp to persue.  Is there some type of sampling
results (your definition) that this approach is precluding?
or perhaps those few short paragraphs I mentioned aren't possible?

				Rae McLellan

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