With the releases of IDV 4.0 and NetCDF-Java library and THREDDS Data Server version 4.3, the IDV and TDS teams have been working to transition the IDV to take full advantage of the improvements in TDS 4.3.
One aspect of this transition is the upgrade of the Unidata Program Center's "official" TDS to version 4.3. Because TDS version 4.3 includes a complete rewrite of GRIB1 and GRIB2 file handling, intended to correct problems that exist in version 4.2's handing of tables and time interval coordinates, it is necessary to match your IDV version with the correct TDS version. However, we understand that moving to a new version of the IDV and accessing data from a new data server during the school semester may cause some uneasiness. We've come up with a transition plan that we hope will address your concerns for the remainder of the Spring 2013 semester, while at the same time allowing us to make the necessary upgrades to the Unidata TDS.
Why is an upgrade necessary?
Its important to realize that currently about 25% of the GRIB variables on the motherlode TDS are being handled incorrectly by TDS 4.2. These problems are fixed in TDS 4.3. For more information on why the move to netCDF-Java and TDS 4.3 is necessary, please browse a portion of the discussion that has taken place over the past year:
- https://www.unidata.ucar.edu/blogs/news/entry/netcdf_java_library_and_tds
- https://www.unidata.ucar.edu/blogs/developer/en/entry/grib_renaming
- https://www.unidata.ucar.edu/blogs/developer/en/entry/on_the_suitability_of_grib
- https://www.unidata.ucar.edu/blogs/developer/en/entry/grib_table_case_studies
- https://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2012/msg00048.html
- https://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2012/msg00060.html
- https://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2012/msg00123.html
- https://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2012/msg00240.html
Ok, so when will this happen?
The timeline for transitioning from the TDS 4.2 to the 4.3 server at Unidata is as follows:
-
Friday, March 22nd, 2013 - the official data access URL for
the Unidata TDS will be
thredds.ucar.edu. This address will resolve to a TDS 4.3 server (the latest version). -
Saturday, June 1st, 2013 - the previous data access URL,
motherlode.ucar.edu, will be changed to use the TDS 4.3 server. This marks the end of TDS 4.2 access on Unidata systems. -
Thursday, August 1st, 2013 - the data access URL
motherlode.ucar.eduwill no longer provide THREDDS Data Services. All users of the Unidata TDS should transition to usingthredds.ucar.eduby this time.
What does this mean for IDV users?
That depends on which version of the IDV you are using:
- If you or your lab are currently using the IDV version 3.1 (or earlier), then you will not need to do anything special for the remainder of the Spring Semester. By June 1st, 2013, you must upgrade to the latest version of the IDV (currently 4.0).
-
If you are currently using IDV 4.0 and are ready to make
the transition, simply start accessing the Unidata server at
thredds.ucar.edu by typing the following URL into the
Catalog address box in the Data Choosers tab:
http://thredds.ucar.edu/thredds/catalog.xml
Note that the default catalog used by the IDV,https://www.unidata.ucar.edu/georesources/idvcatalog.xml, will include a link to thethredds.ucar.eduserver under "Unidata IDD Model Data" once the transition to TDS 4.3 has been made on March 22nd, 2013. -
If you are currently using IDV 4.0, use bundles, and
would like to continue using the older version of the Unidata
TDS (version 4.2), you will need to install a plugin to allow
IDV 4.0 to keep using the older TDS. The required plugin is
available in the IDV plugin manager under the plugin category:
Data Sources > Motherlode TDS 4.2 persistence (for IDV 4.0)
Using this plugin should ensure that the IDV continues to interface with the TDS server as it did in previous versions, at least until June 1st 2013. After June 1st, you should uninstall this plugin.
Will all of my bundles break?
We don't believe so. Many of the changes between TDS 4.2 and 4.3, such as new GRIB variable names and new access URLs, are handled 'under the hood' in the IDV and netCDF-Java libraries, which is why older bundles should continue to work. However, there are some features of the TDS 4.2 that are not yet implemented in TDS 4.3. The decision not to implement all TDS 4.2 features immediately was based on initial feedback that these features were confusing or unnecessary — specifically, the "constant forecast offset" and "constant forecast hour" features of the TDS Forecast Model Run Feature collections (FMRC), which have been replaced by the GRIB feature collections. We know these features will be missed by some, but we hope to restore them to the TDS in the future.
Can I test my bundles with TDS 4.3 and the IDV 4.0?
If you are using IDV version 4.0 and would like to test how the new TDS 4.3 server works with existing bundles, you can install the "Test Unidata TDS 4.2 -> 4.3 Upgrade" plugin, also found in the IDV plugin manager. If you've downloaded this plugin previously, you should remove it and install it again, as we needed to make some changes to the plugin to accommodate the timeline above. This plugin will work once the official Unidata TDS, thredds.ucar.edu, moves to 4.3 (scheduled for this Friday, March 22). Note: if you install this plugin, you will need to remove the TDS 4.2 persistence plugin — you may use one plugin or the other, but not both.
Lastly, we hope you will help us to spread this transition information in the IDV user community. If you know of someone who uses the IDV, please check with them to make sure they are aware of these upcoming changes. As always, feel free to contact us if you have questions, comments, or concerns, at support-idv@unidata.ucar.edu.
