Changes between Initial Version and Version 1 of ServiceBinding


Ignore:
Timestamp:
07/02/07 14:27:00 (14 years ago)
Author:
lawrence
Comment:

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  • ServiceBinding

    v1 v1  
     1== NDG Service Binding == 
     2 
     3==== DIF ==== 
     4 
     5 
     6==== Introduction ==== 
     7 
     8How should NDG DIF producers make use of the DIF [http://gcmd.gsfc.nasa.gov/User/difguide/related_url.html related_url]? 
     9 
     10Examples on the web include the following: 
     11{{{ 
     12Group: Related_URL 
     13   URL_Content_Type: GET DATA > OPENDAP DIRECTORY (DODS)  
     14   URL: http://ferret.wrc.noaa.gov/cgi-bin/nc/data/coads_climatology.nc 
     15   Group: Description 
     16      The following dataset is available on this DODS Server: 
     17      COADS Global Ocean Climatology SST, Air Temp and Winds 
     18   End_Group 
     19End_Group  
     20}}} 
     21{{{ 
     22Group: Related_URL 
     23   URL_Content_Type: GET SERVICE > GET WEB MAP SERVICE (WMS)   
     24   URL: http://www.kgis.scar.org/cgi-bin/kgis_wms?coads_climatology.nc 
     25   Group: Description 
     26       OGC WMS service for SCAR KGIS data  
     27   End_Group 
     28End_Group  
     29}}} 
     30The key point to note is that the URL_Content_Type should be taken 
     31from a [http://gcmd.nasa.gov/Resources/valids/url_type.html keyword list].  
     32Regrettably, this is not a version controlled list, and it appears volatile, 
     33we may have to take our own copy and control it properly ... (not all members have full 
     34definitions, but some are defined on this  
     35[http://gcmd.nasa.gov/User/difguide/url_content_type_definitions.html page] - which itself 
     36is from a previous version of the controlled list!). 
     37 
     38There are two classes of problem: what do we want to happen with NDG produced DIFs? That is, what do we expect to produce in OUR MOLES documents, and where they should go in the DIF? The second is what should we do with 
     39third party DIFs and mini-MOLES? 
     40 
     41==== NDG ==== 
     42 
     43From an NDG point of view, five content types are of significant interest, the first two of which are fairly obvious. 
     44 
     45 * VIEW EXTENDED METADATA - which should point to an NDG-B browse instance of the corresponding data entity. 
     46 * GET RELATED DATA SET METADATA (DIF) - which could point to a related dataset (DIF). 
     47 
     48The next two are less obvious, we have a choice between 
     49 * GET DATA, and 
     50 * GET SERVICE > GET WEB FEATURE SERVICE (WFS) 
     51I think we should begin by using GET DATA pointing at our proto-WFS as it is built, and change-over to the second when we have a properly functioning WFS. In any case, I think we should have all the CSML granule endpoints 
     52to be exposed, which will require populating the description rather carefully. Probably a sentence which 
     53defines what we are pointing at, and a sentence which is taken from the CSML granule title. 
     54 
     55We may also want to use the  
     56 * GET SERVICE > ACCESS WEB SERVICE configured for the DX, with the same comments as above for granules. 
     57 
     58Of slightly lesser interest, we may also wish to use 
     59 * VIEW PROJECT HOME PAGE. 
     60 
     61So for example, for one dataset we might have: 
     62{{{ 
     63<Related_URL> 
     64 <URL_Content_Type> GET DATA </URL_Content_Type> 
     65 <URL> http://badc.rl.ac.uk/ndgWFS?uri=badc.nerc.ac.uk__CSML__granule0123</URL> 
     66 <Description> CSML: The dataset is available at this URL via the NDG WFS. This link 
     67 is granule "Seasonal Mean Model Levels" </Description> 
     68<Related_URL>  
     69<Related_URL> 
     70 <URL_Content_Type> GET DATA </URL_Content_Type> 
     71 <URL> http://badc.rl.ac.uk/ndgWFS?uri=badc.nerc.ac.uk__CSML__granule0124</URL> 
     72 <Description> CSML: The dataset is available at this URL via the NDG WFS. This link 
     73 is granule "Monthly Mean Model Levels" </Description> 
     74<Related_URL>  
     75<Related_URL> 
     76 <URL_Content_Type> GET DATA </URL_Content_Type> 
     77 <URL> http://badc.rl.ac.uk/ndgWFS?uri=badc.nerc.ac.uk__CSML__granule0125</URL> 
     78 <Description> CSML: The dataset is available at this URL via the NDG WFS. This link 
     79 is to granule "Daily Data Model Levels" </Description> 
     80<Related_URL> 
     81<Related_URL> 
     82 <URL_Content_Type> GET DATA </URL_Content_Type> 
     83 <URL> http://badc.rl.ac.uk/ndgWFS?uri=badc.nerc.ac.uk__DIF__datasetA</URL> 
     84 <Description> NDGA: The dataset is available at this URL via the NDG WFS. This link 
     85 is to all data granules within the dataset. </Description> 
     86</Related_URL> 
     87<Related_URL> 
     88 <URL_Content_Type> VIEW EXTENDED METADATA </URL_Content_Type> 
     89 <URL> http://badc.rl.ac.uk/browse?uri=badc.nerc.ac.uk__MOLES-B1__datasetA</URL> 
     90 <Description> NDGB: NDG browse metadata can be used to understand more about the data, 
     91and it's relationship to other datasets </Description> 
     92<Related_URL> 
     93}}} 
     94 
     95Note that this proposal is suggesting an internal controlled vocabulary for the '''Description''' entry, which is invoked if the first word, prior to a colon, is one of NDGA, NDGB, or CSML. For the moment, we will only 
     96care about cases where CSML appears; in that case, the first sentence should be preserved into and out 
     97of MOLES, and the second should be preserved into and out of MOLES as a granule title (into will only occur 
     98for the production of mini-MOLES). (However, the NDGA and NDGB signifiers will allow the other related URLs  
     99to appear in the *right* place in MOLES). 
     100 
     101The appropriate entries will appear in MOLES at: 
     102 
     103{{{ 
     104Kev? 
     105}}} 
     106 
     107==== Non-NDG Records ==== 
     108 
     109We should simply parse all non-NDG records directly into a related URL, and parse them back out again preserving their content identically. 
     110 
     111 
     112 
     113