page 3
CONTENTSCEOS Task Force on Planning and Analysis Reports
Activities of Working Group on Calibration and Valldatlon, (WGCV)
CEOS Inventory Interoperability Experlment---This page
The Global Climate Observing System (GCOS): Plan for Space-Based Observations
Analysis of the Great Hanshin Earthquake by Using Satellite Data
Feasibility Study for a CEOS Developing Country Space Information System
The Global Climate Observing System (GCOS):
Plan for Space-Based Observations (continued from page 4)
CEOS Plenary/IAI/Highlight/Calender
CEOS Inventory Interoperability Experiment
Richard Gobel
Scientific Officer
DFD/DLR
(German Aerospace Research Establishment)
George Saxton
Catalog Subgroup Chair
NOAA/NESDIS
The multi-agency CEOS Inventory Interoperability Experiment has been initiated by the CEOS Working Group on Data/Catalog Subgroup. The goal of this experiment is to investigate how different catalogs can be accessed from a single user interface. Current members of this experiment are NASA GSFC, ESA ESRIN, NASDA, DARA, CCRS and DLR.
- The key concept of an interoperable catalog system is a standardized
interface specification (protocol) for all involved catalog systems. The
interface specification has to define the possible messages between the
client and the catalog systems and the method how they are exchanged (network,
transport mechanism etc.). At the beginning of the experiment in 1992 NASA
and ESA suggested two different protocols for this purpose. The protocol
for the NASA Information Management System (IMS) was defined for the version
O of the NASA Earth Observation System Data and Information System (EOSDIS).
This protocol allowed to access the catalogs of nine archive centers (Distributed
Active Archive Centers) in the U.S.A. from a single IMS-client. In a similar
way, the ESA UIT protocol was designed to interconnect European catalogs.
During a first phase of the experiment a prototype was implemented to investigate these two protocols. This prototype includes IMS and UIT servers for every European catalog. The servers have to translate UIT and IMS requests into requests to the local catalogs and to transform the system response into the appropriate form. The prototype also includes a UIT to IMS protocol converter (UIT Bridge) to allow the access to the American catalogs from the European user interfaces. With this prototype the feasibility of both protocols and their compatibility was demonstrated. The experience gained from this implementation has been summarized in a lessons learned document.
Meanwhile the prototype has been extended by new IMS servers for catalogs of CCRS and NASDA. Also a NASDA client has been added to the prototype; this client is connected via a NASDA bridge to the IMS protocol world. The following diagram shows the current structure of the implemented prototype.
After successfully finishing the first phase, the second phase of CINTEX began in spring 1994. The major goals for this second phase are:
* The preparation of the implemented prototype for a preoperational phase
* The operation of the prototype during the preoperational phase in cooperation with some pilot users (user validation phase)
* The modification and extension of the existing protocols to overcome identified weaknesses from the first phase and to extend the functionality of the protocols.
The preparations for the user validation phase are almost finished. The validation phase will start in June 95 and last 6 months. The results of the user validation phase will be summarized in an updated lessons learned document.
The task team prepares a functional model document as the basis for the extension of the protocols describing a network of interoperable catalog systems. A first version of this document will be available at the end of July '95. After finalizing this document the task team will decide on the next steps for the protocol extensions.
Previous Page
Back to a Newsletters list