International Standards Workshop: Archiving and XML Take Center Stage

By John Garrett and Donald Sawyer

Panel 2 of the Consultative Committee for Space Data Systems (CCSDS) held its fall 2002 workshop from 30 September - 4 October 2002. The following week from 7-8 October 2002, a joint CCSDS and Object Management Group (OMG) meeting was held. Both meetings were in Houston, TX just prior to the SpaceOps2002 meeting and the World Space Congress 2002. This fall's Panel 2 meeting proved to be an exciting time. Some archiving standards reached final approval as other efforts were just getting underway. The XML thrusts within Panel 2 were emerging as dominant themes for current work. And updates to software tools, supporting previous standards, were announced.

The CCSDS Panel 2 meeting opened with its sessions on archiving standards. Panel 2 is in the process of developing digital archiving standards for the International Organization for Standardization (ISO). The Reference Model for an Open Archival Information System (OAIS), which was developed by this group, has become the premier digital archiving standard. The OAIS Reference Model has now been approved as a full ISO Standard (ISO 14721:2002) and it is being used far beyond the Space Domain. For NSSDC and NASA it is also important that OAIS is also being adopted in the Space Domain. Besides the use at NSSDC and by some missions contributing to the NSSDC, OAIS concepts are guiding implementations at the French Space Physics archive and NASA's Life Science Archive. OAIS functions are also being used as a basis for modeling at NASA's Atmospheric Sciences Data Center (at the Langley DAAC) and others are considering it for future projects.

As a follow-on from the OAIS Reference Model work, the panel is progressing well on the Producer-Archive Interface Methodology Abstract Standard. This panel draft was reviewed with the intent of converting it to a Draft Standard by the end of the year. The French Space Agency, CNES, is preparing software tools to support the standard. During the archiving sessions, there were also reports on strong preliminary work toward a standard for Archive Certification with leadership from the Research Library Group. CCSDS intends to track this activity and some participation from the international Space community is expected. Those interested in monitoring the progress on the CCSDS Archiving Standards efforts can watch the ISO Archiving Standards site maintained by NSSDC at http://ssdoo.gsfc.nasa.gov/nost/isoas.

The remainder of the CCSDS Panel 2 meeting was dominated by the continued embrace of XML by the space community. This is an exciting time as many concepts developed by the Panel have been undergoing a renaissance as new implementation techniques and tools become available through the use of XML. The European Space Agency (ESA) is revising their Control Authority data-description-registration implementation to use XML. XML tools and strategies are also prompting CCSDS Panel 2 to give new thought to expanding their Control Authority concepts. It seems that there is everywhere a new interest in the concepts of Registries and Repositories.

Packaging of data is also being looked at from an XML point of view. To date satisfactory XML packaging methods are still developing. CCSDS is building on the ideas from the original CCSDS Structure and Construction Rules Standard, as well as the Information Packing concepts from the Open Archival Information Systems (OAIS) Reference Model, to develop an XML packaging solution for the space domain. Panel 2 has a rapid development program underway to bring forward a Draft Standard this year and a full CCSDS Standard by the end of next year.

Work is also being started to produce an XML Schema concrete syntax for the Data Entity Dictionary Specification Language (DEDSL). Previously an Abstract version, a PVL concrete syntax, and an XML/DTD concrete syntax version for DEDSL have been standardized. This additional concrete syntax is being created partly because of the ease with which maintainable tools can be produced with this new technology.

The remainder of the meeting covered several topics on the continued development and use of previous CCSDS Panel 2 standards. Work continues on EAST tool development at CNES as an ever wider range of projects is using EAST data descriptions. One interesting project is ESA's DEBAT project, which aims to integrate many individual existing tools into a workbench and to create a repository of data types which are useful for telemetry and telecommand in order to encourage reuse of the data types. CCSDS Panel 2 is also providing draft material for the CCSDS P1J Orbit Data Messages Draft Standard. The panel is contributing to the work of the CCSDS Architecture Working Group and the CCSDS Reorganization Team. The panel also presented a number of papers at SpaceOps2002 covering many aspects of the Panel's work, including usage of the OAIS reference model and the use of XML in the Space domain.

For further information on any of these topics, contact Donald Sawyer at Donald.Sawyer@gsfc.nasa.gov or John Garrett at John.Garrett@gsfc.nasa.gov.