Expanded NetCDF support: Difference between revisions

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== Definitions ==
== Definitions ==


;NetCDF4 Data Model: The collection of data types and their interrelations as defined by NetCDF4. It is not a software library but an abstract design.
;NetCDF4 API: The library that implements the NetCDF4 Data Model. This same library also implements the netCDF3 data model and contains a separate API that can be used only with those kinds of files. The netCDF4 API can read file written using the netCDF3 API.
;NC_CLASSIC_MODEL: Constant defined by the netCDF4 API to indicate that although a file is being written as a NetCDF4 file, possibly using chunking and/or internal compression, it otherwise follows the definitions of the netCDF3 data model.


== Background ==
== Background ==

Revision as of 23:32, 13 January 2011


Expanded NetCDF Support

Use Cases

NC4.1: Files that use the NetCDF4 Classic model

File that conform to the NC_CLASSIC_MODEL data model as documented by Unidata will open and work without error.

Although the files use only data model features found in the netCDF 3 data model/API, using the netCDF 4 API will enable chunking and internal compression if the files in question were written that way.

To be safe, the software that writes the files should use the NC_CLASSIC_MODEL when it makes/modifies the file(s).

NC4.2: Files that use some new features

The specific features that will be supported are:

  • All of the External Data Types except the int64 and uint64.
  • Enum: Supported by using an int and a set of attributes
  • Opaque: Supported by using a Byte array and an attribute indicating that the data are to be treated as an atomic entity
  • Groups: Encoded using slash (/) characters in variable names in a way that is compatible with the convention established by The HDF Group and NASA for HDF5 files.

NC4.3: Files that use (potentially) all new features

These will fail with an error message indicating they are not supported along with the specific feature that caused the failure.

Unsupported NetCDF4 model/API features are:

Definitions

NetCDF4 Data Model
The collection of data types and their interrelations as defined by NetCDF4. It is not a software library but an abstract design.
NetCDF4 API
The library that implements the NetCDF4 Data Model. This same library also implements the netCDF3 data model and contains a separate API that can be used only with those kinds of files. The netCDF4 API can read file written using the netCDF3 API.
NC_CLASSIC_MODEL
Constant defined by the netCDF4 API to indicate that although a file is being written as a NetCDF4 file, possibly using chunking and/or internal compression, it otherwise follows the definitions of the netCDF3 data model.

Background

Design

Deliverables

Period of use