XML Workshop Convened by NOST

Panel two of the Consultative Committee for Space Data Systems (CCSDS), in conjunction with the CCSDS Technical Steering Group, sponsored a five-day eXtensible Markup Language (XML) workshop at the Raytheon facility in Landover, Maryland, beginning August 20, 2001. It was organized by the NASA/Science Office of Standards and Technologies (NOST) at NSSDC with support from other GSFC and JPL individuals.

Given the extraordinary momentum of XML developments and tools, it was felt that a look at their implications for the space domain was both appropriate and timely. The purpose of the workshop was to identify appropriate XML based techniques that can be promoted as standards in the near term and to do this in a way that would make substantial progress. The scope of the workshop covered all of the space domain, from on-board to deep archives.

The workshop issued an open invitation to participate, but attendance was limited by space and the need to make rapid progress. Ultimately 26 individuals from government, industry, and academia participated. Their expertise ran from onboard instruments, through mission operations, to long term archives. The workshop opened with a one-day plenary session with presentations from participants to set context and identify requirements. The plenary concluded the second morning and then broke into two working groups identified as “Data Description” (WG1), chaired by Peter Shames/JPL, and “Data Packaging” (WG2), chaired jointly by David Giaretta/British National Science Center (BNSC) and Lou Reich/CSC.

The Data Packaging need had previously been identified and draft requirements, both from past CCSDS packaging standards and from a W3C working group, were distributed prior to the workshop. The draft was reviewed and updated based on known and expected packaging needs associated with ground distribution and storage of information in both mission operations and archiving scenarios. Several on-going XML based data packaging efforts in non-space specific domains were examined to see what could be adopted or adapted. These included IMS, MPEG21, and METS. While these efforts will continue to be tracked, a very preliminary XML schema definition of a packaging approach was developed and this included the option of a package form using ZIP to hold binary files. While substantial progress was made, much more work needs to be done to complete this effort and those willing to contribute should make themselves known to the authors.

The Data Description (WG1) agenda was much less tightly defined prior to the workshop, and this lent itself to looking at broader issues associated with the use of XML in the space domain. They looked at XML and non-XML based description languages targeted at different, but overlapping, domains of the space environment, including instrument data description, telemetry and telecommand, and archival data. They looked at the need for establishing overarching models, a glossary, and data dictionaries to improve cost-effective handling and usage of data. They also came to the view that CCSDS was the right forum to pursue this standardization, and they developed a plan calling for the establishment of a CCSDS Technical Working Group to continue the XML based standards effort.

Coordination between WG1 and WG2 was accomplished by exchanges between the chairs at the end of each day, and by an impromtu plenary session held Thursday morning. The final plenary was held Friday morning where it was clear there was strong support for continuing this effort. A "CCSDS XML" Web site has been set up to provide a focus for the effort. Presentations from this workshop and draft materials are available, as well as a preliminary report. You will also be able to make your interest in participating known through this site at http://www.ccsds.org/xml/.

For further information please send E-mail to Donald Sawyer at Donald.Sawyer@gsfc.nasa.gov or John Garrett at John.Garrett@gsfc.nasa.gov.

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