An Extensible Markup Language (XML) schema was developed as a means of defining and describing a structure for capturing spacecraft command-definition and tracking information in a single location in a form readable by both engineers and software used to generate software for flight and ground systems. A structure defined within this schema is then used as the basis for creating an XML file that contains command definitions. The schema is divided into three sections:

  • Header information, including information about the project and XML file to be derived from the schema;
  • Project-specific definitions of types, roles, and allowable values of data; and
  • The information necessary for defining the command structure, including the information necessary for generating all pertinent software.

Among the advantages afforded by XML for such applications are the following:

  • There exist commercial off-the-shelf (COTS) software tools and standard scripting-language modules for parsing XML schemata. These tools and modules facilitate the ingestion of XML files for use.
  • By use of COTS software tools, the structures of, and some properties of the data in, XML files can be validated against their parent XML schemata to detect errors early.

This work was done by Sharon Laubach, Celina Garcia, Scott Maxwell, and Jesse Wright of Caltech for NASA’s Jet Propulsion Laboratory. For more information, contact This email address is being protected from spambots. You need JavaScript enabled to view it.. NPO-42332

NASA Tech Briefs Magazine

This article first appeared in the November, 2008 issue of NASA Tech Briefs Magazine.

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