In a bid to facilitate and promote data exchanges among space scientists, the
CDF office has developed a web service called Data Translation Web Service
(DTWS) and a client to talk to DTWS via a web browser. The DTWS is a web
service based on the Simple Object Access Protocol (SOAP), an XML-based
protocol designed for the exchange of information in a distributed computing
environment, and it allows users to translate one or more local and/or
remote files into other data formats. Below is a list of the data translation
modes that are currently supported:
CDF-to-netCDF
CDF-to-FITS
CDF-to-ASCII (Text dump of a CDF file)
CDF-to-CDF Skeleton table
CDF-to-CDFML (XML representation of CDF)
CDFML-to-CDF
netCDF-to-CDF
netCDF-to-ASCII (Text dump of a netCDF file)
FITS-to-CDF
FITS-to-ASCII (Text dump of a FITS file)
HDF4-to-CDF
HDF5-to-CDF
HDF5-to-ASCII (Text dump of a HDF5 file)
DTWS Client
Since it's not a trivial task for most scientists to learn how to invoke the
DTWS service by writing a program, the CDF office has developed a web browser
client through which end users can specify one or more local and/or remote
files, have the specified files translated, and download the translated files.
Upon completion of the requested data translation, the users will be
presented with a list of the translated files for http download.
Double-clicking on the hypertext linked file name will initiate the file
download to the user's local machine/disk. The DTWS client can be invoked
by going to this URL
http://translators.gsfc.nasa.gov from a web browser.
When users submit a file translation request, they can either
wait for the data translation to complete (default) or provide an email
address (optional) if they don't want to wait for the data translation
to complete. If an email address is provided, the names of the translated
files along with their locations will be sent to the specified email address.
We are trying to make this data translation service as useful as possible
and would greatly appreciate for your testing and any feedback. Please send
any comments/suggestions/problems to cdfsupport.
How to Invoke DTWS within an Application
Since DTWS is a SOAP-based web service, it can be invoked by applications
written in any of the programming languages that support SOAP binding (e.g. C,
C++, Java, Perl, IDL, JavaScript, etc.). The DTWS uses the RPC/encoded WSDL
binding style. Please note that the service can't use RPC/literal or
Document/literal because it uses an javax.activation.DataHandler object to
receive a binary CDF file.
If you would like to translate local files (files on your local machine/desktop),
you will have to use Java (unless you want to transfer your local files to
a remote machine prior to data translation) since it is the only language
(as far as we know) that allows sending binary and text files as
arguments/parameters.
Here is the info about the data translation web service:
If you developing a client application in Java, we
have a static stub available for download at
http://translators.gsfc.nasa.gov/pub/dtws/dtServiceStub.jar.
We strongly encourage the use of our static stub (instead of generating
your own from a WSDL file) since it contains the correct Java DataHandler object.
Note that there are different versions of DataHandler objects available
from different sources and some of them might not be compatible with
the one used in the DTWS service.
The following sample programs show how the DTWS services can be called
for translating local and remote files:
Most of the translators described above are available either in binary or
source code. The CDF-to-ASCII tool (cdfexport) is included in the CDF
distribution package, and this tool is available in the <cdf_install_dir>/bin
directory. We use the tools included in the HDF4 and netCDF packages for the
translation of HDF5-to-ASCII (h5dump) and netCDF-to-ASCII (ncdump). These
two tools are not distributed by us and available from the
HDF and netCDF web sites.
Source Code Download
If you would like to have a copy of any of the translators listed below
installed on your local machine or desktop, please download the
translator(s) of interest and follow the instructions in the README.install
or INSTALL file.
