Towards a CCSDS XML Packaging Approach in the ESA Data Disposition System
Nestor Peccia, Michael E. Dyck, Alvaro Espada, Richard Corkill · SpaceOps 2002 Conference · 2002
There is a great need in the future at ESA for a general purpose packaging mechanism for XML and related files. End users wish to collect, describe relationships between files, compress and package files together for easy transmission over the Web when accessing Mission Archives. They have the additional need to save the content and associated metadata such that the entire unit can be resurrected into the appropriate Databases and File Managers. XML packaging will also improve the transmission efficiency if the dynamic creation of components, within Web servers, is part of such a package. ESA Science missions and instruments continue to produce volumes of useful data and users depend on the data systems and tools that archive this data as a means to access and analyse it. These ESA data systems (Earth Observation, Astrophysics, Space Plasma, and High Energy Physics) do not interoperate well, are heterogeneous and geographically distributed. Users must access each data system and its corresponding science data independently through tools that have been custom-built for the particular science data system or mission. An even larger effort is to correlate these data sets across a multidisciplinary ESA effort. New emerging technologies could provide support for a future ESA electronic data interchange system between heterogeneous data sources, i.e.: q The Extensible Mark-up Language (XML) q the Common Object Request Broker Architecture (CORBA) q JAVA Programming Language The general objective of this approach is to find out a solution to be easily and flexibly adopted by the ESA archives (in parallel to their development) and that improves their openness to other archives. The CCSDS is currently developing XML packaging standards for the space domain. ESA ‘s approach is based on the requirements identified by the CCSDS Panel 2, and it will provide valuable input to it by identifying the strengths and weaknesses of some of the approaches to data packaging using XM technology. This paper demonstrates the applicability of XML technology to the packaging of data for ESA’s space archive systems, and in particular by O Analysing existing ESA archives and identifying on a selected ESA reference archive the functions that could be implemented using XML technology. O Specifying a general purpose, flexible, powerful and highly interoperable mechanism for collecting files into a group, adding metadata about the relationships between files, compressing, encrypting, authenticating, dynamically transmitting, processing incrementally, packaging and randomly accessing XML and related files. The current packaging mechanism (CCSDS Panel 2 SFDU Standard) used by the ESOC Data Disposition System is considered in the XML approach (either by embedding or replacing it). O Evaluating; comparing the different existing mechanism for physically packaging components (XML, ZIP, MIME, etc.)