Greetings IDV community!
The IDV and THREDDS teams have been working hard on transitioning the
IDV to the latest version of netCDF-Java, as well as making
modifications to allow the IDV to take advantage of the newest version
of the THREDDS Data Server (TDS version 4.3).
The time has arrived for the official Unidata TDS to transition to
version 4.3. There are very important improvements in this version,
especially fixing incorrect GRIB data handling, affecting ~25% of all
GRIB parameters from NCEP models. 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 are we doing this? Why is an upgrade necessary?
---------------------------------------------------
For more information on why the move to netCDF-Java and TDS 4.3 is
necessary (including fixing incorrect handling of GRIB-1/2 data
formats), please browse a very small selection of the discussion that
has taken place over the past year or so:
http://www.unidata.ucar.edu/blogs/news/entry/netcdf_java_library_and_tds
http://www.unidata.ucar.edu/blogs/developer/en/entry/grib_renaming
http://www.unidata.ucar.edu/blogs/developer/en/entry/on_the_suitability_of_grib
http://www.unidata.ucar.edu/blogs/developer/en/entry/grib_table_case_studies
http://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2012/msg00048.html
http://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2012/msg00060.html
http://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2012/msg00123.html
http://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2012/msg00240.html
(yes, this is a 'very small' portion of the discussion!)
The bottom line is that you WANT to make this transition, and we
strongly encourage you to do so now. If you need to delay this until
the semester is over, then we have ways for you to do that, detailed
below.
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.edu
will no longer function. All users of the Unidata TDS should
transition to using thredds.ucar.edu by this time.
What does this mean for IDV users?
----------------------------------
Well, that depends on which version of the IDV you are using.
1) 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).
2) 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,
http://www.unidata.ucar.edu/georesources/idvcatalog.xml, will include
a link to the thredds.ucar.edu under "Unidata IDD Model Data" once the
transition to TDS 4.3 has been made this Friday.
3) 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 4.2 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 stuff 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' of 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. This decision was based
on initial feedback that these features were labeled 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 this will be missed by some, but we hope
to have these features back in the TDS in the future.
Want to test your 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 previous 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
needed 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 know that many IDV users are not subscribed to this list.
If you know of someone who uses the IDV, please contact them to make
sure they are aware of these very important upcoming changes. As
always, feel free to contact us if you have questions, comments, or
concerns, at support-idv@xxxxxxxxxxxxxxxx.
Cheers,
The IDV and THREDDS Development Teams
