# Presentation: 752253

## A DistributedScience-Data-Description Registry/Repository:Implementation and Operational Experience

**Donald Sawyer/NASA/GSFC**
**John Garrett/SPSystems**
**November 14, 2007**
**GDFR Governance Workshop**

## Overview of Presentation

**Control Authority (CA) Office and context**
**CA Concept and Standards**
**Current CA Organization and Status**
**CA Registration Issues**
**Closing Thoughts**
**References for CA standards**

## Control Authority Offices

**NASA has operated one or more Control Authority Offices (CAOs) since 1994**
**Register descriptions of scientific data, INCLUDING their formats**
**Assign globally unique identifiers**
**Support long-term data understanding, and the reuse of registered data descriptions**
**Operate in conformance with international standards**
**SFDU-Control Authority Procedures, June 1993, CCSDS 631.0-B-1/ISO 13764**
**SFDU - Control Authority Data Structures, November 1994,  CCSDS 632.0-B-1/ISO 15395**
**However original expectations for scope and operation of distributed CAOs has not been fully met**
**Let’s look at the context**

## What is CCSDS ?

**Consultative Committee for Space Data Systems**
**International collaboration of space agencies, starting 1982**
**Develops a variety of science-discipline-independent standards**
**Became the working body for ISO TC 20 / SC 13 about 1990**
**TC20: Aircraft and Space Vehicles**
**SC13: Space Data and Information Transfer Systems**
**Information Interchange Panel (1982-2003)**
**Facilitate and promote the interchange, preservation, and use of space related information**
**Develop Recommendations (standards) in areas of location, access, transfer, understanding, usage, and archiving of information, e.g.:**
**SFDU-Control Authority Procedures, 1993**
**Reference Model for an Open Archival Information System (OAIS), 2002**
**Reorganized (2003) into Data Archive Ingest Working Group, Information Packaging/Registry Working Group, and recent Repository Audit and Certification BOF working group**

## Information Interchange Problem

**Much space-science observational data may be characterized as data products:**
**Long sequences of complex, repetitive, data structures**
**Need description of data structure’s format and associated meanings**
**Space agency participants in CCSDS recognized the utility of registering descriptions of science data products**
**Data descriptions could be better preserved, and improved, and would have unique identifiers**
**Unique identifiers could be more easily associated with the complex data structures, thereby improving data/documentation linkage**
**Resulting program of work led to:**
**Standard data packaging with associated unique identifiers**
**Operational procedures and data structures for a distributed Control Authority Organization that registers and disseminates data descriptions**

## Control Authority (CA)

## Registration Requirements

**Distributed, federated, Control Authority Offices (CAO) register and disseminate descriptions**
**Data descriptions available separately from data product instances**
**Provide access over time to data descriptions**
**Ensure knowledge of data description existence**
**Standard way to identify location of data descriptions**
**Internationally unique identifier (ADID)**
**Capability to accept standard service requests**
**Capability to modify data descriptions**
**Provide notification of updated data descriptions**

## Control Authority Service Concept

**Data Producer sends a data description to a Member Agency Control Authority Office (MACAO)**
**Description sent as a standardized Registration Package (RP) or Revision Registration Package (RRP)**
**MACAO converts the Registration Package to a registered Data Description Package (DDP)**
**Unique identifier, called an Authority and Description ID (ADID), is returned to the Data Producer**
**Data Producer incorporates the ADID within the data product**
**Data product is exchanged/disseminated to data users**
**Data User contacts the MACAO**
**Provides the ADID**
**Receives the registered Data Description Package**
**Able to understand the data product**

## Control Authority Organizational Structure

-    (WDC-SI)

## Control Authority Procedures

**2 CONTROL AUTHORITY ORGANIZATION AND RESPONSIBILITIES ...............**
**3 PROCEDURES FOR USER SERVICES**... .................................................................**7**
- 3.1 Request Processing .............................................................................................7
- 3.2 User Services Provided by the CA Agent................................................................8
- 3.2.1 CCSDS Data Description Dissemination......................................................8
- 3.2.2 Control Authority Annual Report Dissemination...........................................8
- 3.3 User Services Provided by the MACAO ..................................................................9
- 3.3.1 Data Description Registration .....................................................................9
- 3.3.2 Data Description Dissemination ..................................................................10
- 3.3.3 Data Description Revision ..........................................................................12
**4 PROCEDURES FOR INTERNAL ADMINISTRATION**.. .............................................**1 3**
- 4.1 CCSDS Secretariat Internal Administration ..............................................................13
- 4.1.1 Establishing a MACAO ..............................................................................13
- 4.1.2 Dissolution of a Primary MACA O.................................................................14
- 4.1.3 CA Annual Report Publication....................................................................14
- 4.2 MACAO Internal Administration ..............................................................................15
- 4.2.1 Establishing a Descendant MACAO ...........................................................15
- 4.2.2 Dissolution of a Descendant MACAO .........................................................16
- 4.2.3 MACAO Annual Report Production ............................................................16

**http://public.ccsds.org/publications/archive/630x0b1.pdf**

## CA Agent Primary Responsibilities

**Disseminate CA associated CCSDS standards**
**Ensure uniqueness of MACAO Control Authority IDs (CAIDs)**
**Maintain organizational information on established MACAOs.  **
**Publish an annual report that summarizes CA organization and activities**
**When a Primary MACAO can no longer fulfill duties, aid in negotiation to identify one which will assume them**
**Assist agencies in establishing Primary MACAOs**
**Provide operational guidelines and instructions to Primary MACAOs**

## Example CA Agent Information(World Data Center - Satellite Information)

_**[National](http://www.nasa.gov/)**__**[ ](http://www.nasa.gov/)**__**[Aeronautics and Space Administration (NASA)](http://www.nasa.gov/)**_*** ***
***USA**** ****Preferred Agency ID:**** N *
***Primary MACAO CAID:**** *_*[NSSD](http://ssdoo.gsfc.nasa.gov/nost/caa/macao_list.html#nssd)*_* *
***Descendant MACAO CAID:**** *_*[NJPL](http://ssdoo.gsfc.nasa.gov/nost/caa/macao_list.html#njpl)*_* *
***Descendant MACAO CAID:**** *_*[NURS](http://ssdoo.gsfc.nasa.gov/nost/caa/macao_list.html#nurs)*_
***MACAO CAID: NSSD**** *
*MACAO Type: Agency Primary *
***Web Page:**** *_*[http:](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*__*[//ssdoo](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*__*[.](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*__*[gsfc](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*__*[.](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*__*[nasa](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*__*[.](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*__*[gov/nost/cao-nssd/cao-nssd](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*__*[.html](http://ssdoo.gsfc.nasa.gov/nost/cao-nssd/cao-nssd.html)*_* *
***MACAO Contact:**** NASA Primary Control Authority Office at the National Space Science Data Center (NSSDC) NASA/Goddard Space Flight Center NASA/Science Office of Standards and Technology (NOST) SFDU Support Office*
*Code 633 Greenbelt, MD 20771 USA *
***E-mail:**** *_*[John.G.Garrett@nasa.gov](mailto:John.G.Garrett@nasa.gov)*_
***Telephone:**** +1 301 286 3575 *
***FAX:**** +1 301 286 1771  *

## MACAO Primary Responsibilities

**Register new and revised data descriptions.**
**Disseminate data descriptions upon request.**
**Ensure availability of data descriptions**
**As necessary, establish Descendant MACAOs (Ascendant MACAOs maintains overall responsibility)**
**Provide operational guidelines and instructions to  Descendant MACAOs**
**Inform Ascendant MACAO of intention to cease operation**
**Assume the preservation, revision, and dissemination duties of any Descendant MACAOs ceasing operation.**
**Maintain statistics of requests for the annual report**
**(Primary MACAO only) Request a CAID for each Descendant MACAO to be established within its  organization**
**(Primary MACAO only) Maintain a log of CAIDs assigned to its Descendant MACAOs.**

## MACAO Data Description Registration: Administrative Attributes

**Identifier (Authority and Description (ADID)**
**includes Control Authority ID (CAID)**
**Revision Number**
**Type of Registration Package**
**Registration, Revision, or Dissemination**
**Title of Registered Description**
**Short Description of Registered Description**
**Revision Comment**
**Submission Date**
**Registration Date**
**Revisable**
**Releasable**
**Originator Identification and Contact Information**
**Reviser Identification and Contact Information**

## Control Authority Data Structures

**http://public.ccsds.org/publications/archive/632x0b1.pdf**

**Establishes a standard package for submitting registration information**
**Uses SFDU data packaging standard (CCSDS 620.0-B-2) that encapsulates data/metadata objects, each with a specific ADID and classification**
**Identifies small set of classifications for the contained metadata objects**
**C = data administration service**
**K = catalog information (registration attributes)**
**D = format information (structure)**
**E = data entity dictionary information (semantics)**
**S = supplementary information**
**C class object allows incorporation of other Descriptions by reference to their ADIDs, thus supporting reuse**
**Representation Network is supported through ADIDs**
**Establishes a standard package for the dissemination of registered data descriptions**

## Current CAO Organizational Structure and Status

## Control Authority Offices

**CNES - French Space Agency**
**FCST - CNES/Centre Spatial de Toulouse**
**ESA - European Space Agency**
**EESA - European Space Agency (ESA) Primary Control Authority Office**
**ECLU - ESA CLUSTER Mission Control Authority Office**
**EEUR - ESA EURECA Mission Control Authority Office**
**EHUY - ESA Huygens Mission Control Authority Office**
**EMEX - ESA Mars Express Mission Control Authority Office**
**EXMM - ESA Huygens Mission Control Authority Office**
**NASA**
**NSSD - NASA Primary CAO at the National Space Science Data Center (NSSDC)**
**NJPL - Jet Propulsion Laboratory Control Authority Office**
**NURS - Upper Atmospheric Research Satellite Control Authority Office**

## CAO Activity

**No new Control Authority Offices visible to CA Agent have been established since 2000**
**Although these are ISO standards, no organization outside CCSDS has asked to participate**
**CAO activities have been largely local**
**No CA Agent report since  1996**
**Activity appears confined to ESA and NASA**
**ESA believed to still be using ADID registered descriptions in their dissemination of spacecraft telemetry data**

## CAO Activity (2/3)

**NASA’s descendant MACAOs are no longer active**
**NJPL, at Jet Propulsion Laboratory **
**Planetary Data System created it own media volume directory structure for holding data products and data descriptions**
**Most descriptions were submitted on hardcopy**
**NURS, at Goddard Space Flight Center**
**Active only during the life of the mission**
**NJPL and NURS descriptions have not been sent to NASA’s primary MACAO at the National Space Science Data Center (NSSDC)**

## CAO Activity (3/3)

**NSSD, NASA’s primary MACAO, continues to register data descriptions**
**NSSDC has adopted OAIS Archival Information Package concepts**
**AIP packaging implementation incorporates ADIDs**
**NSSD has assigned about 560 ADIDs, starting in 1989**
**About 300 have little description- need conversion from current forms**
**99 registered descriptions are visible from the Web**
**10 registered descriptions have been revised**
**Descriptions are submitted and registered for all newly arriving data**
**Descriptions are registered for older data undergoing migration into AIPs**

## NSSD Description Characterization

**All expressed in ASCII**
**However, some PDF and TIFF is planned**
**Data structures are both ascii and binary**
**Data structure ‘types’ include:**
**FITS**
**CDF**
**CDF with ISTP conventions**
**PDS Labels**
**Flat File (2-file pair)**
**IDFS (multi-file)**
**GIF**
**Numerous unique data structures**
**Wrapping encodings include:**
**GZIP**
**ZIP**
**TAR**

## NSSD CAO Registration Issues

**Multiple encodings of a data object are not conveniently supported**
**e.g., data object’s format is described, then data object has been compressed, and is stored**
**Work around is to assign new ADID to combination of, for example, format and compression, resulting in ADID proliferation**
**ADIDs are often assigned with minimal description so as to support operational needs**
**Resources for description submission are not always keeping pace**

## Closing Thoughts

**Long term commitments are hard to maintain unless they are integral to the organization’s business model and technical approach**
**NSSDC science data-description-registration needs:**
**Ability to associate different semantics with an underlying data structure description**
**Ability to create a Representation Network**
**NSSDC, as an archive, would probably want to download externally registered format descriptions to ensure its data objects remain understandable**
**May not be necessary if external registry becomes sufficiently stable and reliable (trusted repository)**

## Sources for CCSDS CA Recommendations

**CCSDS 620.0-B-1 *****Standard Formatted Data Units -- Control Authority Procedures,***** ****http://public.ccsds.org/publications/archive/630x0b1.pdf,**** June 1993.**
- Also known as ISO 13764:1996
**CCSDS 622.0-B-1 *****Standard Formatted Data Units -- Control Authority Data Structures, *****http://public.ccsds.org/publications/archive/632x0b1.pdf**** November 1994.**
- Also known as ISO 15395:1998
**CCSDS Report - CCSDS 631.0-G-2: *****Standard Formatted Data Units -- Control Authority Procedures Tutorial, *****http://public.ccsds.org/publications/archive/631x0g2.pdf**** November 1994.**