The NASA/Science Office of Standards and Technology (NOST) has been active the past couple of months facilitating the work on the International Organization for Standardization (ISO) Data Archiving Standards effort and supporting formal reviews of draft standards generated by the Consultative Committee for Space Data Systems (CCSDS). This article will describe the efforts in both these areas beginning with data archiving efforts.
Two meetings were held recently to support development of ISO Archiving Standards. The Fifth U.S. ISO Archive Standards workshop was held October 2-3, 1996, at the National Archives and Records Administration's Archives II facility in College Park, Maryland. Full information on that meeting is available at http://bolero.gsfc.nasa.gov/nost/isoas/us05/ws.html. Following quickly after the Fifth U.S. Workshop was the Third International Workshop hosted by DLR, the German Space Agency. The workshop was held November 4-5, 1996, at DLR's facilities in Oberpfaffenhofen near Munich. Information on that meeting, including minutes, can be accessed through its Web page at http://bolero.gsfc.nasa.gov/nost/isoas/int03/ws.html.
The major focus of this meeting was the continuing development of the the Reference Model for Open Archival Information Systems (OAIS). The most recent version is available from http://bolero.gsfc.nasa.gov/nost/isoas/ref_model.html. This model is addressing the lack of common terms and concepts surrounding what it means to be performing a true archival function for digital information. This lack greatly inhibits the ability to compare and contrast existing archives, to evaluate the performance of archives, and to encourage vendor support in meeting archival requirements. To be truly effective, the Reference Model must be useful to as wide a community as possible, and it must be easily understandable to that community. For example, the editors and reviewers of the Reference Model are attempting to be as consistent as possible with another excellent report, Preserving Digital Information from the Task Force on Archiving Digital Information, available at http://www.rlg.org/ArchTF/.
Another important aspect of the two recent meetings is that discussions have been initiated on plans for development of additional standards. NOST currently expects to have a draft version of the OAIS Reference Model available for formal review by the CCSDS and ISO communities within the next year. By that time NOST expects that the work on the model will have helped identify areas for further standardization to be worked on concurrently with the final reviews of the OAIS Reference Model. NOST has scheduled several future U.S. Workshops on ISO Data Archiving Standards where these ideas will be discussed further.
January 15-16, 1997 Sixth U.S. Data Archiving Workshop April 16-17, 1997 Seventh U.S. Data Archiving Workshop May 1997 Fourth International Data Archiving Workshop July 16-17, 1997 Eighth U.S. Data Archiving Workshop
NOST encourages participation in the U.S. efforts by all interested parties. Whether interested in just reviewing the resulting documents or in editing and reviewing sections of the documents, readers may fill out the form at http://bolero.gsfc.nasa.gov/nost/isoas/us/registration_form.html. Readers unable to access the World Wide Web form can respond by E-mail to Donald Sawyer at firstname.lastname@example.org.
The NOST is also coordinating the final stages of the formal GSFC and NASA reviews of two CCSDS Panel 2 Red Books. CCSDS Red Books are draft Recommendations circulated for formal review by the member agencies. When the comments received during the Red Book reviews are suitably addressed, CCSDS produces a Blue Book, which is a final Recommendation or Standard. These books are then generally forwarded to ISO for adoption as ISO standards.
The first document is the SFDU-Referencing Environment Red Book, which defines "file pointer" mechanisms that can be embedded into other data structures including SFDU data structures. These "file pointer" mechanisms can be used when there is a need to link the internals of a file with other files (such as actual data records and the associated files providing information about the data records) when transferring such collections across computer systems or when storing them for future use. This document provides mechanisms that allow the formation of those links and allow for those links to be maintained to ensure the collections and their relationships are properly understood.
The second document under review is the Enhanced Ada Subset (EAST) Red Book. Since it is clear that there will always be a variety of data structures, the EAST document addresses the problem of documenting data structures in a computer interpretable manner. For a variety of reasons, data structures are often chosen that reflect the influence of various operating systems or the sensor environments that generated them. Thus, the information is not easily understood by all users. Even when documentation of the data structures exists, it is often incomplete or ambiguous. The EAST Specification addresses these problems by defining a language that can be used to describe the information representations of a record or file in a non-ambiguous manner. Once this description is in hand, generic software could be used to access data values.
Based on the few comments received, it appears that these books may progress from their status as Red Books toward that of Blue Books, or final Standard status, this spring. Interested indivduals can watch here for announcements in future issues of NSSDC News. Individuals can also access copies of any approved CCSDS Recommendation or Report by accessing the CCSDS Publication Web page at http://bolero.gsfc.nasa.gov/ccsds/ccsds_publications.html.
In closing, there is one other item from the CCSDS Panel 2 International Workshop to mention. The Committee on Earth Observing Satellites (CEOS) has formally asked CCSDS Panel 2 to organize a review of their Catalogue Interoperability Procotol (CIP). The CIP addresses many problems associated with seeking catalog information from distributed catalogs, and it is known to be of interest to many in other NASA science disciplines. NOST is expecting to receive a version that may be informally reviewed by the agencies in the next few months. NOST will keep its readers informed on how to obtain a copy.
Erin D. Gardner, email@example.com, (301) 286-0163
Hughes STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.