EOSDIS V0

The Earth Observing Systems Data and Information Systems (EOSDIS) Version 0 is a protocol for NASA-sponsored open, distributed information system. EOSDIS Version 0 system is now called the EOS Data Gateway (EDG) that is an extension of the original Version 0 system. EOSDIS manages the data and information from a variety of pre-EOS and EOS-era Earth observation satellites, as well as data from related Earth science field measurement programs. The goal of the EOSDIS Version 0 and the EDG is to provide seamless access to distributed archives at NASA EOSDIS Distributed Active Achieve Centers (DAACs), affiliated data centers, and international data centers in a single online session. There are currently over 965 data products spread over 8 NASA DAACs and 6 international data centers searchable and retrievable from the EDG.

The EDG system is a typical client/server system. The EDG is the client, or a single WWW interface through which users can find and order data from multiple participating archives. The EOSDIS Version 0 IMS is cooperatively developed between the IMS system level coordination/development team and the distributed DAAC software development teams.

The basic protocol (known as the Version 0 protocol) between the EDG client and a V0 server consists of a set of requests constructed in Object Description Language (ODL). Five services are provided by the EDG:

1. Inventory Searching

Inventory searching allows users to search for data granules based on standard search criteria, which includes at a minimum a source, sensor, or parameter selection and geographic specifications. Servers are expected to return information about granules that satisfy at least one of the values in each of the fields requested (i.e., the values within each field are OR'ed for the search and the fields are AND'ed together). The EXTENDED_SEARCH group allows dataset-specific search criteria to be added. Use of the extended search criteria is described in more detail in the metadata section.

2. Directory Searching

Directory searching allows users to search for summary documents for specific datasets. Servers respond with a DIRECTORY_RESULT message to provide the Global Change Master Directory (GCMD) DIF identifier for each matching dataset.

3. Browse Requests

Using information returned in an inventory search, a user could request browse products either to be staged for ftp or to be returned directly through the V0 protocol. V0 systems are normally limited to a single integrated browse file per request.

4. Product Requests

Using information returned in an inventory search, a user can order product packages from the data center. Once the PRODUC-REQUEST is received by a server, it returns a PRODUCT-RESULT to acknowledge the request. Tracking information is returned in the result, since there is no guarantee of acceptance of the request by the result message.

5. Guide Searching

Guide document, or detailed document searching is performed using WAIS queries against standard WAIS servers, and http protocols for following internal hypertext linkage. No ODL messages are used to support guide document searching.