Discovery and Access TechnologiesThe data discovery and access technologies designated as Standards in the table below have been approved by the NASA Earth Science Division (ESD) for use in Earth science data systems. The Technical Notes describe other useful data discovery and access technologies with implementation details and/or lessons learned. The full list of NASA ESD approved standards and technical notes, as well as information on the standards submission and approval process, is available on the Standards Process Group (SPG) page.
Data Access Protocol (DAP)NASA ESD-approved Standard The OPeNDAP Data Access Protocol (DAP), a data transmission protocol designed specifically for science data. The protocol relies on the widely used and stable HTTP and MIME standards, and provides data types to accommodate gridded data, relational data, and time series, as well as allowing users to define their own data types. Web Map Service (WMS)NASA ESD-approved Standard NASA ESD Technical Note The OpenGIS® Web Map Service Implementation Specification (WMS) describes a technology for disseminating views of raster and vector data (“maps”) via the World Wide Web. WMS uses HTTP and defines several operations that allow a client to discover the functions a server is capable of providing, request a specific ”map”, and, optionally, request information about individual features shown on a map. At the time of review by the SPG (late 2005), it was determined that there was not widespread use of WMS 1.3 and that most users of WMS were using version 1.1.1. WMS 1.1.1 is a widely implemented and widely deployed specification that provides a standard way of performing a specific set of tasks. Future installations of WMS should consider use of the most recent version. WMS 1.3 is identical to ISO 19128, which the International Organization for Standardization (ISO) released as an International Standard during calendar year 2005. Web Coverage Service (WCS)NASA ESD Technical Notes The OpenGIS® Web Coverage Service provides an interface allowing requests for geographical coverages across the web using platform-independent calls. The coverages are objects (or images) in a geographical area, whereas the WMS interface or online mapping portals like Google Maps return only an image, which end-users cannot edit or spatially analyze. WCS has not yet been reviewed by the SPG as a potential NASA ESD standard. These two technical notes provide lessons learned in implementing WCS at GES DISC. Backtrack Orbital Search AlgorithmNASA ESD Technical Note The reference implementation of the Backtrack Orbit Search Algorithm is currently in operational use at NASA’s National Snow and Ice Data Center as well as at the NASA-developed Earth Observing System (EOS) Clearinghouse (ECHO). The backtrack algorithm is a spatial search method for orbital data. Using a simplified orbital model, Backtrack starts with the area of interest and answers the question “In order for the sensor to have seen this area, where must the satellite have crossed the equator?” The Backtrack Orbit Search Algorithm reference implementation generates SQL queries that can be used with any conventional relational database. |
