enveloping, batching, signing

[Kirk Borne]

Hi.  Here are some "facts" pertaining to the LSST events....

1)  The science requirements document for LSST requires that all
events be identified and published to the world (VOEventNet) within
60 seconds of the end of each pair of exposures.  (One pair =
15sec expose + 5 sec readout + 15sec expose + readout & slew.)
So, the events will *not* be saved up as a "night's worth of events".

However....

2)  The Pan-STARRS project will find nearly all asteroids in advance
of LSST, by several years.  Therefore, LSST will "know" about these
asteroids and their orbits (likely tracks & positions within the images).
In these cases, since these are known objects, they are not *events"
in the usual "telegram alert" sense.  Hence, LSST will *not* be sending
alerts to the VOEventNet for known objects (asteroids, variable stars,
quasars, blazars, ...).

So, I think that things will not be quite as extreme as you might imagine
coming out of the LSST pipeline ... e.g., _*maybe*_ "only" 10-100 VOEvent
messages every 60 seconds, and perhaps significantly less.

- Kirk

Steve Allen wrote, On 02/04/2008 01:46 PM:
> With the galleys for the VOE/HTN conference paper on my desk I
> find myself wondering about the implementation of digital signatures
> for VOEvent, but also, more generally, about the use cases in the
> era of Pan-STARRS and LSST.
>
> If there be thousands of asteroid candidates daily, do we expect that
> they will send out individual VOEvent packets for every single one?
> (Maybe so, at least for the exceptional cases of imminent impactors,
> but most cases will be main belt asteroids of no urgent interest.)
> Are they going to prefer to process the night's worth of data
> until they have a digested list of candidates and then send that
> whole list out once daily as a huge batch?
>
> So would it make more sense to define some sort of VOEvent envelope
> into which arbitrary numbers of fully-formed VOEvent documents could
> be transmitted?
>
> If the latter, then the use case question for digital signing of the
> VOEvents might be better if the envelope contains the signature which,
> under most cases, would externally sign all of the VOEvent documents
> in the envelope.  This would alleviate the need to include the
> complexity of the W3C Signature element in the VOEvent proper, and it
> would greatly simplify and speed the authentication process.
>
> But in closing I note that if there are not two parties already
> exchanging VOEvent packets who find utility in digital signing,
> then there may not be enough justification to bother including
> it at all.
>
> --
> Steve Allen                 <sla at ucolick.org>                WGS-84 (GPS)
> UCO/Lick Observatory        Natural Sciences II, Room 165    Lat  +36.99855
> University of California    Voice: +1 831 459 3046           Lng -122.06015
> Santa Cruz, CA 95064        http://www.ucolick.org/~sla/     Hgt +250 m
>
>   
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