THREDDS Technical Status

THREDDS Data Server (TDS)
1. Stable release is 3.16.35.
  1. Level II NEXRAD radar server allows user to subset by station, space, and time. Integrated with IDV chooser.
  2. Netcdf Subset for Grids as Points
  3. Write any GridDataset as CF compliant netCDF file
  4. Write UnidataStationObsDataset netCDF file
2. Most work is on the 4.0 branch, still experimental:.
  1. Level III NEXRAD radar server allows user to subset by station, space, time and product
  2. Experimental WCS 1.0+ server
  3. Integrating Spring into TDS for long term maintainability. We will incrementally move functionality over to it.
Common Data Model
1. Stable release 2.2.22.20 is in maintenence mode.
2. Current work is on a 4.0 release. A pre-alpha early access version is available.
  1. HDF4 IOSP is complete. Ongoing work to decode HDF-EOS coordinate systems
  2. GEMPAK Grid IOSP
  3. NMC Office Note 29/143 IOSP for CADIS datasets.
  4. RotatedPole projection
3. CDM Data Access
  1. Structure.select(): create subset consisting only of selected member variables
  2. Sequences allow iteration through 1D structures (experimental)
4. CDM Scientific Feature Types
  1. CDM Feature Types draft doc
  2. CDM Point Feature Types draft doc
  3. CF Conventions for Point Data (proposed)
  4. New pass on implementation in ucar.nc2.dt2 package (ongoing).
5. NcML
  1. Tiled aggregation
  2. JoinExisting accepts timeUnitsChange
  3. Union accepts scan

THREDDS Data Server (TDS): Current release is 3.16.
1. Current work is on a 4.0 release.
  1. Clean up / fix NcML aggregation.
  2. Uses netCDF-Java 4.0
  3. Upgrade WCS to version 1.1. Experiment with WCS-REST.
  4. NetCDF file writing consistently encoded in CF Conventions.
2. Taught 2-day Unidata workshop on THREDDS Data Server Administration.
3. Latest version of Live Access Server (LAS) from PMEL is now built on TDS.

Common Data Model: Current release is 2.2.22.
1. Current work is on a 4.0 release. A pre-alpha early access version is available.
  1. This will read netCDF-4 file formats, and hopefully allow complete access to HDF5, including HDF5-EOS. Writing netCDF-4 format may not be feasible, however.
  2. The entire library is extensively refactored, and the APIs are being stabilized based on the new features of the netCDF-4 file format.
  3. NcML is extensively refactored, in order to add new features (like tiled aggreagtion).
2. Preparing to work with OPeNDAP to continue data model reconciliation, as part of the SDCI proposal.
3. Taught 1-day Unidata workshop on Writing an I/O Service Provider
4. CF working group for encoding Point Observation datasets in netCDF.

International Standards:
1. Open Geospatial Consortium (OGC) fall meeing hosted by UCAR. One of the days was OGC Interoperability Day at Unidata: Standards-based Web Services Interfaces to Existing Atmospheric/Oceanographic Data Systems, where 50+ participants explored connections bewteen ISO/OGC standards and Unidata and related technologies.
2. Working with an international group (British Atmospheric Data Center, British Met, and others) to define WCS 1.0 extentions, and help drive further version of WCS.

THREDDS Data Server (TDS): Current release is 3.16.
1. The NetCDF Subset Service is an experimental REST web service for subsetting CDM scientific datasets. The subsetting is specified using earth coordinates, such as lat/lon bounding boxes and date ranges, rather than index ranges that refer to the underlying data arrays. The data arrays are subsetted but not resampled or reprojected, and preserve the resolution and accuracy of the original dataset.
2. New authorization/authentication capabilities allow servers to be configured with restricted dataset access.
3. Forecast Model Run Collections : Automatically create 1D subsets of 2D time datasets. (Example)
4. Runtime configuration completed, allows users to configure, load classes at runtime.
5. Dataset Source plugin: allows users to create custom and virtual datasets.
6. Refactor of dataset filter interface (CrawlableDatasetFilter) simplifies new implementations
7. TDS Tutorial will be updated for next Unidata workshop.
8. OPeNDAP server: direct implementation of ascii ascii response (not recursive call)

Common Data Model: Current release is 2.2.20, last stable release using Java 1.4.
1. Joint development with opendap.org
  - Proposal accepted to merge OPeNDAP/netCDF library with netCDF-4 library
  - Add all necessary capabilities for HTTP authentication in OPeNDAP Java library
2. Radial Datatype Collections now can be visualizeed in the IDV
3. Starting to handle McIDAS AREA files : McIdasAreaProjections, prototype IOSP.
4. NcML
  - Specify IOSP class, parameter, buffer_size.
  - New aggregation types: ForecastModelRunCollection, ForecastModelRunSingleCollection, JoinExistingOne.
5. Runtime configuration completed, allows users to configure, load classes at runtime.
6. GRIB files
7. Allow bzip2 compression.
8. Netcdf Tutorial will be updated for next Unidata workshop.

International Standards:
- FeatureType Meeting in Abingdon, UK (CCLRC Rutherford Appleton Laboratory, British Atmospheric Data Center) to look at harmonizing the data models used in CDM, CSML, and OGC/ISO standards.

This document is maintained by John Caron

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