This is the OPeNDAP 4 Data Server, also known as Hyrax.

Hyrax is a new data server which combines the efforts at UCAR/HAO to build a high performance DAP-compliant data server for the Earth System Grid II project with existing software developed by OPeNDAP. The server is intended to be a replacement for the existing 3.x servers which OPeNDAP is distributing.

The new server uses the Java servlet mechanism to hand off requests from a general web daemon to DAP format-specific software. This results in higher performance for small requests. The servlet front end, which we call the OPeNDAP Lightweight Front end Server (OLFS) looks at each request and formulates a query to a second server (which may or may not on the same machine as the OLFS) called the Back End Server (BES). The BES is the high-performance server software from HAO. It handles reading data from the data stores and returning DAP-compliant responses to the OLFS. In turn, the OLFS may pass these response back to the requestor with little or no modification or it may use them to build more complex responses. The nature of the Inter Process Communication (IPC) between the OLFS and BES is such that they should both be on the same machine or be able to communicate over a very high bandwidth channel.

Both the OLFS and the BES require installation and configuration before they can be run.

Find Your Hyrax Server Here...

If Tomcat is running and Hyrax is installed you could:



OPeNDAP user and developer documentation is now located at the OPeNDAP Documentation Site

There you will find:

Hyrax Documentation


Hyrax supports THREDDS catalogs, look here for configuration details.

SOAP Support

Hyrax supports SOAP requests.

A prototype SOAP interface is included with this release of Hyrax. It is discussed in the RSG template pages here. Example client code can be found distributed at our web site, and can be found in our Subversion archive here.


We hope we hope you find this software useful, and we welcome your questions and comments.

To Contact Us:

Technical Support: support@opendap.org


Hyrax Java Development:

OLFS: ndp <AT> opendap <DOT> org

Hyrax C++ Development:

BES: pwest <AT> ucar <DOT> edu

Libdap: jgallagher <AT> opendap <DOT> org



OPeNDAP Hyrax development is sponsored by:

NSF National Science Foundation

NASANational Aeronautics and Space Administration

NOAA National Oceanic and Atmospheric Administration