Lineage scenarios

From Earth Science Information Partners (ESIP)

Scenario

Based on the CEOP Satellite Data Server - Data Fed - GSFC use case:

Suppose we have a Live Access Server accessing GO-CART model output from an OPeNDAP/OGC gateway server at URI, which obtains the input from a WCS server at DataFed, which in turn obtained the GO-CART model from GSFC.

The LAS would have a hyperlink that would request a "lineage" response corresponding to a specific OPeNDAP request, e.g., if the OPeNDAP data request is http://test.opendap.org:8080/opendap/wcs/DataFed/GoCart/NetCDF/GOCART_G_OL.SUEXTTAU.2007-09-18.030000.wcs then the lineage request would be: http://test.opendap.org:8080/opendap/wcs/DataFed/GoCart/NetCDF/GOCART_G_OL.SUEXTTAU.2007-09-18.030000.lineage

The OPeNDAP/OGC Gateway server, in order to satisfy such a request, would make a request to the WCS server whence the WCS request came. If the WCS request were: http://webapps.datafed.net/ogc_NASA.wsfl?SERVICE=WCS&REQUEST=GetCoverage&VERSION=1.0.0&CRS=EPSG:4326&COVERAGE=GOCART_G_OL.SUEXTTAU&TIME=2007-09-18T03:00:00&BBOX=-180,-70,180,70,0,0&WIDTH=361&HEIGHT=181&DEPTH=-1&FORMAT=NetCDF then the lineage request would be: http://webapps.datafed.net/ogc_NASA.wsfl?SERVICE=WCS&REQUEST=GetLineage&VERSION=1.0.0&CRS=EPSG:4326&COVERAGE=GOCART_G_OL.SUEXTTAU&TIME=2007-09-18T03:00:00&BBOX=-180,-70,180,70,0,0&WIDTH=361&HEIGHT=181&DEPTH=-1&FORMAT=NetCDF

This request might be made immediately after the GetCoverage request, and the result cached on spec, or could be made at lineage request time.

For prescriptive lineages, the request could be made even BEFORE the GetCoverage request, and a client might choose to modify or even demur on the GetCoverage based on the GetLineage response. ("What? You're using that questionable input product? No, thanks!") But since descriptive lineage would not support this, this sequencing would have to be treated as an optional service.