XML - James Webb space telescope database issues, lessons, and status

Abstract

-This paper will present the current concept using extensible Markup Language (XML) as the underlying structure for the James Webb Space Telescope (JWST) database. The purpose of using XML is to provide a JWST database, independent of any portion of the ground system, yet still compatible with the various systems using a variety of different structures. The testing of the JWST Flight Software (FSW) started in 2002, yet the launch is scheduled for 201 1 w i t h a planned 5-year mission and a 5-year follow on option. The initial database and ground system elements, inc!udir?,o fie c o~m x~~d s , tekmeey, and ground system tools will be used for 19 years, plus post mission activities.During the Integration and Test (I&T) phases of the JWST development, 24 distinct laboratories, each geographically dispersed, will have local database tools with an XML database. Each of these laboratories database tools w i l l be used for the exporting and importing of data both locally and to a central database system, inputting data to the database certification process, and providing various reports. A centralized certified database repository will be maintained by the Space Telescope Science Institute (STScI), in Baltimore, Maryland, USA.One of the challenges for the database is to be flexible enough to allow for the upgrade, addition or changing of individual items without effecting the entire ground system. Also, using XML should allow for the altering of the import and export formats needed by the various elements, tracking the verificationhalidation of each database item, allow many organizations to provide database inputs, and the merging of the many existing database processes into one central database structure throughout the JWST program. Often this causes a greater reliance on the use of Commercial-Off-The-Shelf (COTS), which is often limiting. In our review of the database requirements and the COTS software available, only very expensive COTS software will meet 90% of requirements. Even with the high projected initial cost of COTS, the development and support for custom code over the 19-year mission period was forecasted to be higher than the total licensing costs. A group did look at reusing existing database tools and formats. If the JWST database was already in a mature state, the reuse made sense, but with the database still needing to handing the addition of different types of command and telemetry structures, defining new spacecraft systems, accept input and export to systems which has not been defined yet, X M L provided the flexibility desired. It remains to be determined whether the XML database will reduce the over all cost for the JWST mission.

Signature search time evaluation in flat file databases

“…Databases for space applications have been discussed in terms of shuttle database integration by Stevens and Componation [26], in terms of the use of XML (extensible markup language) as the underlying structure of the James Webb Space Telescope effort by Detter et al [27] and in terms of NASA's New Millenium project by Some et al [28]. Moreover the NASA Technical Report Server contains material on a wide variety of aerospace-oriented databases, ranging from those for turbulence studies, for images, for astronomical data and for flight tests.…”

“…For the case of a single equivalent processor denote for convenience the transformation function as g eq (¢). Accordingly let Y = g eq (X): (27) Furthermore, since it is clear that g eq (¢) depends on w eq , the inverse speed of the equivalent processor, one can use the (12) as follows:…”