During the week of August 8, 2022, the Unidata Program Center plans to upgrade the THREDDS Data Server (TDS) hosted at https://thredds.ucar.edu to version 5.x of the server software.
TDS version 5 has been in use at community sites since October 2021, but Unidata's primary in-house server has continued to run TDS version 4.6.x in order to ensure continuity for users of data hosted there. In the intervening time, the Unidata TDS development team worked through the process of ensuring that the two versions were feature compatible. In addition, the Unidata Program Center has delayed the changeover of its primary TDS until summer, to minimize any changes needed by students and educators who access the server via the Integrated Data Viewer (IDV) or other technologies as part of their coursework.
TDS version 5 includes a large number of enhancements to the 4.x release series. The configuration catalogs and internal state of the server has been extensively re-worked to be able to scale to large numbers of catalogs, datasets, and internal objects without excessive use of memory. In version 5, a running TDS can be triggered to reread the configuration catalogs without having to restart. It can be configured to reread only changed catalogs, for fast incremental updates. Other features have been added to make writing configuration catalogs more maintainable, including the <catalogScan> element, and default and standard services.
In TDS version 5, GridDataset is replaced by FeatureDatasetCoverage, to better support very large feature collections. The Coverage API works with coordinate values (not array indices), which solves various intractable problems that arise when using array index subsetting on large collections. Additionally, a number of API enhancements have been made to take advantage of evolution in the Java language, for example try-with-resource and foreach constructs. The use of these make code simpler and more reliable.
For more on the changes between TDS version 4.x and version 5, see Upgrading to TDS Version 5 in the online TDS documentation.
The Program Center's plan is to begin redirecting requests to the
domain to the TDS instance currently accessible at
threddsrc.ucar.edu early in the week of August 8, 2022. There may be
some interruption in service, though we hope it will be minimal. If you have any
questions or encounter any problems, please reach out to us at firstname.lastname@example.org.
Additionally, the Program Center would like to remind TDS administrators that we will be completely discontinuing our support for TDS 4.6.x at the end of August, 2022. We encourage 4.6 users to upgrade to v5 as soon as possible.