Quantity "tables"
Tony Linde
ael at star.le.ac.uk
Fri Jan 23 06:56:31 PST 2004
Quick question, Ed: why is everything a <Quantity ... /> element? Why not a
<Galactic_long ... />, <Galactic_lat ... /> etc? Isn't it harder to use the
metadata if you've got to work with types of Quantity rather than specific
elements?
Thanks,
Tony.
> -----Original Message-----
> From: owner-dm at eso.org [mailto:owner-dm at eso.org] On Behalf Of Ed Shaya
> Sent: 22 January 2004 15:56
> To: dm at ivoa.net
> Subject: Quantity "tables"
>
>
> This is a cross-post with VOTable.
>
> Simply put XML is hierarchical and a table is not. Hence,
> there is this misfit between XML tools (XQuery, XPath, XSLT,
> WebServices) and our XML/Table efforts (Astrores, VOTable,
> XDF, Dataset, etc). XML's hierarchies make it more suitable
> for describing an object's structure. Tables are compact and
> human-friendly, especially when one gets to large (but not too
> large) amounts of info. We want it all, but we are
> struggling to make tables fit beautifully into XML, and
> falling into circles of inconsistencies.
>
> In true XML, tables are something to convert to or from.
> XHTML has tables explicitly described, but XHTML is a display
> language. One transforms from your true XML into XHTML only
> at display time.
>
> XML is meant to interchange with relational databases. Using
> a schema based on true XML, one creates a database
> configuration and flattens the documents into one or several
> tables. The tables are now strictly speaking outside of the
> XML realm but an XML front end allows one to address the data
> as if it were still in true XML. Although, it should be
> noted that native XML databases are getting pretty mature and
> maybe we won't be doing this much longer.
>
> I conclude that we should start off with a true XML
> description of data (ie, not tabular) and then after that
> matures, rethink tabular formats, but as either a compressed
> transmission mode or as a display mode or as the internals of
> an object-relational database. That way, all tools interface
> with the data in true XML fashions. If I am right, then it
> would follow that even our image/table display tools like
> Alladin and Mirage would benefit from a hierarchical view of data.
>
> Just to make clear what I mean by a "hierarchical view of
> data", below is an example of the "non-tabular way". This is
> just one galaxy and one must imagine that there are many in
> this object oriented database. It would be easy now to
> extend this to include additional metadata about each
> measurement, who observed it, when, with which instrument,
> etc. It would also be interested to create a little schema
> for each Quantity/@type. A B_T_Quantity.xsd which extends
> Quantity could substitute for the <Quantity type="B_T"/> and
> provide suitable extensions and restrictions on both metadata
> and datatypes.
>
> OK. Now the crux of this all is that the Tabular form of
> this is done by a auto-flattener that simply turns this into
> a series of tables exactly as an XML to DB converter does.
> Now you have a compact form to transfer and one that can go
> right into your local/private DB. If it is an object
> relational DB you should be able to access the data with the
> original true XML schema and XPATH or XQuery.
>
> ======================================================
> <AstroObject type="galaxy" name="NGC 300">
> <Quantity type="altname" name="PGC
> Num"><value>3238</value><units><unitless/></units></Quantity>
> <Group name="position">
> <Quantity type="RA
>
>
> J2000"><value>00:54:52.6</value><units><unit>xs:time</unit></u
> nits></Quantity>
> <Quantity type="DE
> J2000"><value>-37:40:57</value><units><unit>sexigesimal</unit>
> </units></Quantity>
> </Group>
> <Quantity type="Galactic_long"
> name="l"><value>299.2306</value><units><unit>degree</unit></un
> its></Quantity>
> <Quantity type="Galactic_lat"
> name="b"><value>-79.4210</value><units><unit>degree</unit></un
> its></Quantity>
> <Quantity
> type="SGL"><value>259.8113</value><units><unit>degree</unit></
> units></Quantity>
> <Quantity
> type="SGB"><value>-9.4984</value><units><unit>degree</unit></u
> nits></Quantity>
> <Quantity type="brightness absolute B total"
> name="B_T"><value>8.95</value><units><unit>magnitude</unit></u
> nits></Quantity>
> <Quantity type="extinction I-band"
> name="A_I"><value>0.02</value><units><unit>magnitude</unit></u
> nits></Quantity>
> <Quantity type="extinction B-band"
> name="A_B"><value>0.055</value><units><unit>magnitude</unit></
> units></Quantity>
> <Quantity type="axis ratio b/a" shape
> name="b/a"><value>0.73</value><unitless/></Quantity>
> <Quantity type="morphology type T"
> name="Ttype"><value>7</value><unitless/></Quantity>
> <Quantity type="morphology type M"
> name="Mtype"><value>SA(s)d</value><unitless/></Quantity>
> <Group type="velocity radial">
> <Quantity type="geocentric" name="V_gsr">
> <value errorValue="4." >101.</value>
> <units><unit>km</unit><unit power="-1">s</unit></units>
> </Quantity>
> <Quantity type="heliocentric" name="V_helio">
> <value errorValue="4.">144.</value>
> <units><unit>km</unit><unit power="-1">s</unit></units>
> </Quantity>
> </Group>
> <Quantity type="linewidth 21cm @20percentOfPeak" name="W20">
> <value ErrorValue="7.">166.</value>
> <units><unit>km</unit><unit power="-1">s</unit></units>
> </Quantity>
> <Quantity type="distance Cepheid" name="Cepheid dist"><value
> errorVAlue="2.3"
> >26.66</value><units><unit>Mpc</unit></units></Quantity>
> <Quantity type="distance TRGB" name="TRGB
> dist"><value>UNKNOWN</value><units><unit>Mpc</unit></units></Quantity>
> <Quantity type="distance PNLF" name="PNLF
> dist"><value>26.9</value><units><unit>Mpc</unit></units></Quantity>
> <Quantity type="distance SBF" name="SBF
> dist"><value>UNKNOWN</value><units><unit>Mpc</unit></units></Quantity>
> <Quantity type="distance TF" name="Tully-Fisher
> dist"><value>UNKNOWN</value><units><unit>Mpc</unit></units></Quantity>
> <Quantity type="axes"><valueList>21.9
> 15.5</valueList><units><unit>arcmin</unit></units></Quantity>
> <photometry>
> <region>
> <fitsFile href="HSTDA/retrieve/n300.u65w0201r.fits">
> <instrument>WFPC2</instrument>
> <observationDate>2001:05:06</observationDate>
>
> <rightAscension>1.372291666667E+01</rightAscension>
> <declination>-3.768333333333E+01</declination>
> <rotation>168.502</rotation>
> <filters>F814W</filters>
> <exposureTime units="second">40.</exposureTime>
> <proposalId>8599</proposalId>
> <observer>Boeker</observer>
> <history>
> <date>2001:08:24</date>
> <creator>Felicia Tam</creator>
> <item>mosaic of all 4 ccds</item>
> </history>
> </fitsFile>
> <fitsFile href="HSTDA/retrieve/n300.u65w0202r.fits">
> <telescope>HST</telescope>
> <instrument>WFPC2</instrument>
> <observationDate>2001:05:06</observationDate>
>
> <rightAscension>1.372291666667E+01</rightAscension>
> <declination>-3.768333333333E+01</declination>
> <rotation>168.502</rotation>
> <filters>F814W</filters>
> <exposureTime units="second">300.</exposureTime>
> <proposalId>8599</proposalId>
> <observer>Boeker</observer>
> <history>
> <date>2001:08:24</date>
> <creator>Felicia Tam</creator>
> <item>mosaic of all 4 ccds</item>
> </history>
> </fitsFile>
> <fitsFile href="HSTDA/retrieve/n300.u65w0203r.fits">
> <telescope>HST</telescope>
> <instrument>WFPC2</instrument>
> <observationDate>2001:05:06</observationDate>
>
> <rightAscension>1.372291666667E+01</rightAscension>
> <declination>-3.768333333333E+01</declination>
> <rotation>168.502</rotation>
> <filters>F814W</filters>
> <exposureTime units="second">300.</exposureTime>
> <proposalId>8599</proposalId>
> <observer>Boeker</observer>
> <history>
> <date>2001:08:24</date>
> <creator>Felicia Tam</creator>
> <item>mosaic of all 4 ccds</item>
> </history>
> </fitsFile>
> </region>
> <region>
> <fitsFile href="shoko/n300.fits">
> <telescope>HST</telescope>
> <instrument>WFPC2</instrument>
> <observationDate>2001:07:02</observationDate>
>
> <rightAscension>1.375416666667E+01</rightAscension>
> <declination>-3.758000000000E+01</declination>
> <rotation>-154.402</rotation>
> <filters>F814W</filters>
> <exposureTime units="second">600.</exposureTime>
> <proposalId>9162</proposalId>
> <observer>Tully</observer>
> <history>
> <date>2001:07:09</date>
> <creator>Shoko Sakai</creator>
> <item>mosaic of all 4 ccds</item>
> <item>cosmic ray cleaned and summed</item>
> </history>
> </fitsFile>
> <psFile name="NGC 300 Color-Magnitude Diagram"
> href="shoko/n300cmd.ps"/>
> </region>
> </photometry>
> <kinematics>
> <reference>
> <title>H I studies of the Sculptor group
> galaxies. VI - NGC
> 300</title>
>
> <author><initial>D</initial><lastName>Puche</lastName></author>
>
> <author><initial>C</initial><lastName>Carignan</lastName></author>
>
> <author><initial>A</initial><lastName>Bosma</lastName></author>
> <abstract>A study of the kinematics of the
> Sculptor group galaxy NGC 300 is presented. VLA observations
> of the H I line show a dramatically warped H I disk just
> outside the optical disk. A two-component mass model, fitted
> to the data, gives a total mass of 2.4E10 solar masses at the
> last observed point of the rotation curve. This value implies
> an (M/L_B)global about 11 solar masses/solar luminosity for
> the galaxy which is compared with the total dynamical
> (M/L_B)dyn of the group. This comparison suggests that dark
> matter is probably more concentrated around the galaxies of
> the group than uniformly distributed in the intergalactic medium.
> </abstract>
> <bibcode>1990AJ....100.1468P</bibcode>
> </reference>
> </kinematics>
> </galaxy>
>
>
> Ed
>
>
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