Earth Observing System Data Gateway

Abstract

The Earth Observing System Data Gateway (EDG) software provides a one-stop-shopping standard interface for exploring and ordering Earth-science stored at geographically distributed sites. EDG enables a user to do the following: 1) Search for according to high-level criteria (e.g., geographic location, time, or satellite that acquired the data); 2) Browse the results of a search, viewing thumbnail sketches of that satisfy the user s criteria; and 3) Order selected for delivery to a specified address on a chosen medium (e.g., compact disk or magnetic tape). EDG consists of (1) a component that implements a high-level client/server protocol, and (2) a collection of C-language libraries that implement the passing of protocol messages between an EDG client and one or more EDG servers. EDG servers are located at sites usually called Distributed Active Archive Centers (DAACs). Each DAAC may allow access to many individual items, called (e.g., single Landsat images). Related granules are grouped into collections called data sets. EDG enables a user to send a search query to multiple DAACs simultaneously, inspect the resulting information, select browseable granules, and then order selected from the different sites in a seamless fashion.