LAT Data Catalog: Virtual File System

The LAT Data Catalog is a virtual file system maintained in an Oracle database.  Data may be stored at several locations, e.g., SLAC, University of Washington (UW), Lyon (IN2P3), and elsewhere).  The files themselves may be stored:

• On disk in AFS-, NFS-, or XROOTD-managed servers.
• In one of several tape archive systems.
• Or in any combination of the above. 

The Data Catalog simplifies access to data by providing a uniform view of files that is independent of their physical location, and it provides features that are not available in standard file systems, including tagging files with:

• Meta-data attributes (typed name/value pairs) that provide additional information about the data they contain.

• Several physical locations, allowing a file to exist in multiple places for more convenient access.

In addition, the Data Catalog maintains a conventional folder structure even as it provides a group structure, which allows files of different pedigree to be separated while coexisting within the same folder.

The Data Catalog also provides access to files by requesting:

• A file, or a set of files, at a specific location (folder / group).

• A set of files via a meta data query.

JAVA API. Access to the Data Catalog is provided via a Java API that is is under continued development, and features are added regularly. Any Java program running within the SLAC firewall may use this API to take advantage of the full Data Catalog feature set.  The Java API is is available Confluence.  The API can be accessed by a Line-Mode Client, available from SLAC UNIX machines, and by Jython scriptlet processes in the GLAST Pipeline. For additional information, see the Advanced (yellow navbar) section of the workbook.