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OPeNDAP History

1980s & 90s

The history of OPeNDAP unfolds over several decades, starting in the late 1980s when software like netCDF began demonstrating the advantages of data models and access methods based on common abstractions across programming languages. By the early 1990s there was a mismatch between the design of data systems and the use of access patterns within the scientific community. As such, there was a growing need for a data access protocol that could facilitate network access to data held by lead research scientists and across federal data centers.


All of the above set the stage for a 1993 workshop held at the University of Rhode Island in collaboration with researchers from MIT, with funding by NASANOAA, and The Oceanography Society (TOS)1. This workshop was crucial in defining the requirements for a network that could support the idea that “a URL equals a dataset” and “a URL with constraints equals a subset”. This was aimed at making data distributed and the framework discipline-neutral, broadening its usability across various scientific disciplines.


By 1995, with support from NOAA, NASA, and the University of Rhode Island, the first Distributed Oceanographic Dataset System (DODS) was implemented2. The system’s development continued with the support of the National Oceanographic Partnership Program (NOPP), which provided funding to develop the National Virtual Ocean Data System (NVODS), a network-based system using DODS/DAP for seamless access to oceanographic data3.


Following an initial series of regional meetings within the ocean community, which led to significant recommendations, the DAP was refined, data servers were installed, and pilot programs were launched. OPeNDAP Inc. (a nonprofit) was formed in 2000 shortly after receiving NOPP funding to continue maintaining, promoting, and evolving the DODS data access protocol. NVODS as an integrated data system ended with the end of NOPP funding, but by then OPeNDAP, the core infrastructure developed for NVODS, had proven to be a robust data access framework for data exchange.

Significant developments continued with OPeNDAP receiving, for example, NASA funding as part of the Research Education and Applications Solutions Network (REASoN) program to focus on satellite-derived ocean properties. Collaborations with the HYCOM project and development of tools like the MATLAB OPeNDAP Ocean Toolbox expanded the DAP’s reach.


In 2005, the Data Access Protocol 2 (DAP2) was approved as a standard for NASA’s Earth Science Data Systems. By 2006, the first version of the HYRAX server4, based on collaborations with NCAR’s High Altitude Observatory, was released, showcasing the ongoing development efforts of the OPeNDAP group.


The following years saw further adoption and implementation of the DAP protocol across several servers and web applications, facilitating access to a wide range of data types. By 2012, MATLAB integrated support for OPeNDAP natively, and tools like Ferret, PyFerret and PyDAP were introduced by members outside of OPeNDAP, broadening access to the DAP protocol within the scientific community. The diverse adoption of the DAP protocol has largely been possible for OPeNDAP’s open source community approach.

In subsequent years, OPeNDAP continued to secure NSF funding for various projects to continue development of advanced data service protocols, in addition to NOAA support under the OPULS program that led, with active collaboration with Unidata, to the release of DAP4 in 20145.


Since 2017, OPeNDAP has focused on cloud optimization with the Hyrax server in collaboration with NASA EarthData, in addition to improving access patterns to over 109 granules stored using legacy technology. OPeNDAP’s rich history spanning over 30 years reflects its ongoing commitment to interoperability in the scientific community, democratization of data, and Open Science. Furthermore, the broad adoption of DAP technology across the geosciences, from both the server and client side, reflects the impact that OPeNDAP continues to have in the scientific and open source software communities.

Much of the source material for this summary came from:

Cornillon, P., J. Adams, M. B. Blumenthal, E. Chassignet, E. Davis, S. Hankin, J. Kinter et al. “NVODS and the development of OPeNDAP.” Oceanography 22, no. 2 (2009): 116-127. http://www.jstor.org/stable/24860964.


  1. Cornillon, P., Flierl, G., Gallagher, J., & Milkowski, G. (1993). Report on the First Workshop for the Distributed Oceanographic Data System. Zenodo. https://doi.org/10.5281/zenodo.10608009
  2. Gallagher, J. (1995, April 18). An Overview of the Distributed Oceanographic Data System (DODS). Zenodo. https://doi.org/10.5281/zenodo.10627778
  3. Cornillon, P. (2001, 20 November) “NVODS in the End-to-End Oceanographic Data Environment”. Ocean.US, Zenodo, 20 November. Zenodo. https://doi.org/10.5281/zenodo.10632228
  4. Gallagher, J., Potter, N., & West, P. (2007, October 15). Hyrax Architecture. 2007 OPeNDAP System Administrator’s Workshop, Melbourne, Australia. Zenodo. https://doi.org/10.5281/zenodo.10685285
  5. Gallagher, J., & Davis, E. (2014, July 7). DAP4. 2014 OPeNDAP Developers Workshop, Frisco, CO. Zenodo. https://doi.org/10.5281/zenodo.10671500