Terms - Proposals

[Martin Hill]

Again, I would prefer to see 'service' separated from 'data resource', and so I 
don't think the 'query' here is relevent.  To me, if data is served through a 
cone search in one place and a SkyNode in another, if it's the same data it's 
the same data. This is similar to 'download' mirrors; some offer FTP access, 
some HTTP.

Also, because service interfaces differ, you may not get *back* a bitwise copy 
from similar queries; the order may be different, or you may not be able to 
specify a subset of columns.  The data is still a mirror, and we can expect the 
same metadata to be used to describe both.

If the concept of 'mirror vs copy' is too contentious just now, then let us drop 
it and just say that any duplicate dataset is a 'copy', with links to related 
data sets including the original.  We can always factor out similarities later.

Arnold Rots wrote:

> The mirror definition needs to be tightened a bit:
> 
> A mirror will return, bit for bit, the same result as its parent site
> in response to the same query - with one exception: there may be a
> time lag in miorror updating, and maybe that should be specified in
> the mirror's profile.  I.e.:
> 
> A mirror, when presented with a query (or request) Q at time T will
> return a bitwise identical response as its parent site would have
> returned in response to query Q at time T-dt, where dt should be a
> fixed and predictable value (i.e., the time between updates).
> 
> What is exempted from this, of course, is meta-metadata, such as the
> immediate source of the data and information on the transmission.
> 
>   - Arnold
> 
> Roy Williams wrote:
> 
>>>So a mirror will generally always return the same results as the original. A
>>>snapshot can only guarantee to return the same results up until the next
>>>update of the original. An extract can never guarantee to return the same
>>>results.
>>
>>We have astronomical datasets, called A and B.
>>
>>A delivers a lossless compression of B. Are they mirrors?
>>
>>When I query A and B, I get a table of results. A and B have different default sorting 
>>order. Are they mirrors?
>>
>>A delivers much lower bandwidth than B. Are they mirrors?
>>
>>A delivers data with calibration version 3.2 and B delivers calibration versions 3.1 and 
>>3.2. Are they mirrors?
>>
>>A can deliver data from Virgo AND Orion, but B only covers Orion. Are they mirrors?
>>
>>A is available all the time, but B is located in Utah and cannot deliver data on Sundays. 
>>Are they mirrors?
>>
>>A is the server that is mentioned in the peer-reviewed publication by Professor Bigshot. 
>>The B data is a copy made by an irresponsible student, and is not mentionsed in the 
>>Bigshot paper. Are they mirrors? 
>>
> 
> --------------------------------------------------------------------------
> Arnold H. Rots                                Chandra X-ray Science Center
> Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
> 60 Garden Street, MS 67                              fax:  +1 617 495 7356
> Cambridge, MA 02138                             arots at head.cfa.harvard.edu
> USA                                     http://hea-www.harvard.edu/~arots/
> --------------------------------------------------------------------------
> 

-- 
Martin Hill
www.mchill.net
+44 7901 55 24 66