HR: 1340h
AN: IN43A-0326    [Abstracts]
TI: DataFinder: Using Ontologies and Reasoning to Enhance Metadata Search
AU: * Russ, T A
EM: tar@isi.edu
AF: University of Southern California, Information Sciences Institute 4676 Admiralty Way, Marina del Rey, CA 90292-6695 United States
AU: Chalupsky, H
EM: hans@isi.edu
AF: University of Southern California, Information Sciences Institute 4676 Admiralty Way, Marina del Rey, CA 90292-6695 United States
AB: The Southern California Earthquake Center's Community Modeling Environment uses computer codes for simulation and hazard analysis computations. The process of running workflows using several computational models produces numerous intermediate and final data files. These files have descriptive metadata stored as pairs of attribute names and values. Depending on which software was used to prepare the files, different attribute names and different organizational schemes are used for the metadata. Previous search tools for this metadata repository rely on the user knowing the structure and names of the metadata attributes in order to find stored information. Matters are made even harder because sometimes the type of information in a data file must be inferred. For example, seismic hazard maps are described simply as ``JPEGFile'', with the domain content of the file inferable only by looking at the workflow that produced the file. This greatly limits the ability to actually find data of interest. DataFinder uses ontologies to provide a semantic overlay for the metadata attributes that are used to index data files. A domain ontology is combined with a metadata attribute ontology to link geophysical and seismic hazard domain concepts with the metadata attributes that describe the computational products. DataFinder uses a domain ontology and additional rules expressed in first-order logic to provide this semantic enhancement. The domain and metadata attribute ontology is represented in the PowerLoom representation language. DataFinder is implemented using a hybrid reasoning approach based on combining the strengths of the PowerLoom logical reasoning engine with the database technology underlying the metadata repository to provide scalability. The PowerLoom reasoning engine allows to add semantic enhancements by overlaying the raw metadata with a hierarchy of concepts, providing more abstract views of the data collection. For example, a velocity mesh is one of the intermediate data products used in seismic wave propagation simulations. It is the output of a 3-dimensional wave propagation velocity model of the subsurface geology. This mesh can be computed using any one of several models which have different characteristics. Each velocity mesh has metadata that records the specific model used. But the models also fall into general classes such as 1-dimensional and 3-dimensional models. Such classification of models can be used to allow retrieval of velocity meshes created by any 3-dimensional model, without the user being required to specify all of the particular model names. This provides an abstraction over the attributes and values stored with the dataset. Other mappings are used to present a uniform interface to metadata information that is stored using different attribute names or even different organizational schemes. Some data products produced as the output of a computational workflow retain all of the metadata information, whereas others rely on following a chain of references to the intermediate products. By using an ontology as an abstraction layer, DataFinder thus allows users to locate end data products using domain-level descriptions instead of program-specific and varied metadata attributes.
DE: 0525 Data management
DE: 7290 Computational seismology
SC: Earth and Space Science Informatics [IN]
MN: Fall Meeting 2005