TDSCatalog does not include base path in access_url

[jm-cook]

TDSCatalog is not constructing the access_url correctly when there is a base path.

from siphon.catalog import TDSCatalog
cat_url = "https://opendap1-test.nodc.no/opendap/hyrax/DSG/Physics/project/SmartOcean/Austevoll-Nord/catalog.xml"
cat = TDSCatalog(cat_url)
for cds in cat.datasets:
    url = cat.datasets[cds].access_urls['dap']
    print(f'url = {url}')

The result is

url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202205.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202206.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202207.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202209.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202210.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202211.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202212.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202301.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202302.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202303.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202304.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202305.nc
url = https://opendap1-test.nodc.no/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202306.nc

but 'opendap/hyrax' is not in the path.

The correct path should be:

https://opendap1-test.nodc.no/opendap/hyrax/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202205.nc
... etc

In the catalog.xml this is given as base="/opendap/hyrax" for the dap service

<thredds:catalog xmlns:thredds="http://www.unidata.ucar.edu/namespaces/thredds/InvCatalog/v1.0" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:bes="http://xml.opendap.org/ns/bes/1.0#">
<thredds:service name="dap" serviceType="OPeNDAP" base="/opendap/hyrax"/>
<thredds:service name="file" serviceType="HTTPServer" base="/opendap/hyrax"/>
<thredds:service name="WCS-coads" serviceType="WCS" base="/opendap/wcs"/>
<thredds:dataset name="/DSG/Physics/project/SmartOcean/Austevoll-Nord" ID="/opendap/hyrax/DSG/Physics/project/SmartOcean/Austevoll-Nord/">
<thredds:dataset name="NMDC_AR_MO_Austevoll-Nord_202205.nc" ID="/opendap/hyrax/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202205.nc">
<thredds:dataSize units="bytes">1145638</thredds:dataSize>
<thredds:date type="modified">2023-06-23T09:28:13</thredds:date>
<thredds:access serviceName="dap" urlPath="/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202205.nc"/>
<thredds:access serviceName="file" urlPath="/DSG/Physics/project/SmartOcean/Austevoll-Nord/NMDC_AR_MO_Austevoll-Nord_202205.nc"/>
</thredds:dataset>
...

Python version : 3.8.8
Siphon version: 0.9

[jm-cook]

Might be related to #114

However that was fixed?

[jm-cook]

I looked some more into this since I was curious as to why the fix to #114 does not solve my issue. I ran my little test on the oceandata opendap catalog link in #114 (now updated to https://oceandata.sci.gsfc.nasa.gov/opendap/SeaWiFS/L3SMI/2000/0101/catalog.xml) and see the same issue, ie opendap/hyrax is not inserted into the url.

What is happening is that when access_urls is constructed in make_access_urls(), the server_base url is correctly constructed as 'https://oceandata.sci.gsfc.nasa.gov/opendap/hyrax', the url_path is obtained as the absolute path /SeaWiFS/L3SMI/2000/0101/SEASTAR_SEAWIFS_GAC.20000101.L3m.DAY.CHL.chlor_a.9km.nc but then on the next line

                    access_urls[subservice.service_type] = urljoin(server_base,  self.url_path)

urljoin will create the absolute url, so the opendap/hyrax part of the server_base url is lost.

This seems to be how hyrax is presenting the paths (ie with a leading slash).

According to the documentation here: https://docs.unidata.ucar.edu/tds/5.2/userguide/basic_client_catalog.html, the service base, urlPath, and dataset should be concatenated together.

The code below shows the incorrectly constructed access_urls (the urls created cannot be accessed):

from siphon.catalog import TDSCatalog
cat_url = "https://oceandata.sci.gsfc.nasa.gov/opendap/SeaWiFS/L3SMI/2000/0101/catalog.xml"
cat = TDSCatalog(cat_url)
for cds in cat.datasets:
    url = cat.datasets[cds].access_urls['dap']
    print(f'access url = {url}')