1. Ewa Deelman, www.isi.edu/~deelman Virtual Metadata Catalogs: Augmenting Existing Metadata Catalogs with Semantic Representations Yolanda Gil, Varun Ratnakar, and Ewa Deelman USC Information Sciences Institute Yolanda Gil, Varun Ratnakar, and Ewa Deelman USC Information Sciences Institute

2. Ewa Deelman, www.isi.edu/~deelman D a t a a n d / o r A n a l y s i s D i s c o v e r y D a t a, M e t a d a t a a n d P r o v e n a n c e M g n t E x e c u t i o n A n a l y s i s D e f i n i t i o n a n d M a p p i n g A na l ys i s D e sc r i p t i on Scientific Analysis Derived Data Metadata Provenance Raw Data Metadata

3. Ewa Deelman, www.isi.edu/~deelman D a t a a n d / o r A n a l y s i s D i s c o v e r y D a t a, M e t a d a t a a n d P r o v e n a n c e M g n t E x e c u t i o n A n a l y s i s D e f i n i t i o n a n d M a p p i n g A na l ys i s D e sc r i p t i on Scientific Analysis Derived Data Metadata Provenance Raw Data Metadata

4. Ewa Deelman, www.isi.edu/~deelman D a t a a n d / o r A n a l y s i s D i s c o v e r y D a t a, M e t a d a t a a n d P r o v e n a n c e M g n t E x e c u t i o n A n a l y s i s D e f i n i t i o n a n d M a p p i n g A na l ys i s D e sc r i p t i on Scientific Analysis Derived Data Metadata Provenance Raw Data Metadata

5. Ewa Deelman, www.isi.edu/~deelman D a t a a n d / o r A n a l y s i s D i s c o v e r y D a t a, M e t a d a t a a n d P r o v e n a n c e M g n t E x e c u t i o n A n a l y s i s D e f i n i t i o n a n d M a p p i n g A na l ys i s D e sc r i p t i on Scientific Analysis Derived Data Metadata Provenance Raw Data Metadata

6. Ewa Deelman, www.isi.edu/~deelman Raw Data Metadata Derived Data Metadata Provenance Raw Data Metadata Derived Data Metadata Provenance Raw Data Metadata Derived Data Metadata Provenance Raw Data Metadata Derived Data Metadata Provenance

7. Ewa Deelman, www.isi.edu/~deelman Raw Data Metadata Derived Data Metadata Provenance Raw Data Metadata Derived Data Metadata Provenance Raw Data Metadata Derived Data Metadata Provenance Raw Data Metadata Derived Data Metadata Provenance Problem: How to find the data in this environment? How to specify the characteristics of the data (the metadata attributes)? How to manage distributed provenance records? Today clients must figure out manually the meaning of the attributes, identify what are the relevant ones to query, and formulate queries

8. Ewa Deelman, www.isi.edu/~deelman Approach  Expose the information in the catalogs at a semantic level  Expose the attributes  Provide access to the content based on a user-selected ontology  Support semantic queries to the catalog contents  Expose the information in the catalogs at a semantic level  Expose the attributes  Provide access to the content based on a user-selected ontology  Support semantic queries to the catalog contents

9. Ewa Deelman, www.isi.edu/~deelman The Virtual Metadata Catalog  Augments the existing metadata catalogs with semantic representations  Do not modify the original sources  Maps virtual metadata attributes to the original attributes  Represents virtual attributes declaratively  Represents constraints as relations between attributes  Expands and translates a query to the Virtual Catalog into the original attributes  Explored approach with temporal attributes  Augments the existing metadata catalogs with semantic representations  Do not modify the original sources  Maps virtual metadata attributes to the original attributes  Represents virtual attributes declaratively  Represents constraints as relations between attributes  Expands and translates a query to the Virtual Catalog into the original attributes  Explored approach with temporal attributes

10. Ewa Deelman, www.isi.edu/~deelman Queries to other metadata catalogs Mappings Virtual Metadata Shared ontologies & vocabularies Metadata Catalog Metadata Attributes Mappings Virtual Metadata Virtual Metadata Catalog Service Metadata Catalog Service Queries with virtual metadata attributes Queries with metadata attributes Queries to multiple catalogs Query Mediator Queries to a specific metadata catalog

11. Ewa Deelman, www.isi.edu/~deelman Metadata Catalog Service (MCS)  Models logical files, logical collections and views  Provides a standard set of attributes for each object type  Supports the dynamic definition of attributes of type  String, integer, float, date  Provides a command-line interface and a Java API  Used in the Pegasus portal, SCEC, myLEAD  Models logical files, logical collections and views  Provides a standard set of attributes for each object type  Supports the dynamic definition of attributes of type  String, integer, float, date  Provides a command-line interface and a Java API  Used in the Pegasus portal, SCEC, myLEAD

12. Ewa Deelman, www.isi.edu/~deelman Execution time  Wall clock time or CPU time?  Could be specified as:  begin-execution-time, end-execution-time  begin-execution-time, duration  Diversity of these attributes can be represented at a semantic level  Define the virtual attributes in OWL  Wall clock time or CPU time?  Could be specified as:  begin-execution-time, end-execution-time  begin-execution-time, duration  Diversity of these attributes can be represented at a semantic level  Define the virtual attributes in OWL

13. Ewa Deelman, www.isi.edu/~deelman Gratuitous OWL Slide 1 1

14. Ewa Deelman, www.isi.edu/~deelman  Add rules to represent more expressive relations and constraints [r1: (?x rdf:type tme:IntervalThing), (?x tme:from ?a),(?x tme:duration ?t2), (?a tme:at ?t1), sum(?t1, ?t2, ?t3)makeTemp(?v)-> (?v rdf:type tme:InstantThing) (?v tme:at ?t3) (?x tme:to ?v)]  Add rules to represent more expressive relations and constraints [r1: (?x rdf:type tme:IntervalThing), (?x tme:from ?a),(?x tme:duration ?t2), (?a tme:at ?t1), sum(?t1, ?t2, ?t3)makeTemp(?v)-> (?v rdf:type tme:InstantThing) (?v tme:at ?t3) (?x tme:to ?v)]

15. Ewa Deelman, www.isi.edu/~deelman MCS Query Generic Catalog Ontology (file, view, collection) Query Virtual Metadata Attributes and Mappings Reasoner Distributed domain ontologies Virtual Metadata Catalog Metadata Catalog Metadata Attributes Metadata Catalog Metadata Catalog Service (MCS) Query Mapping Answer

16. Ewa Deelman, www.isi.edu/~deelman Query Mapping MCS Query 1. Generate query constituents 2. Convert to MCS Attribute names 3. Construct query formula OWL Query Virtual metadata attribute value pairs MCS Attribute value pairs Distributed domain ontologies Virtual Metadata Attributes and Mappings Metadata Catalog Service (MCS) Generic OWL + Rules Reasoner answer “from 2004-01-01T10:00:00” and “duration PT30S” “startDate” and “endDate” Load OWL ontologies and rules referenced in the query generate new attributes “from 2004-01-01T10:00:00” “to 2004-01-01T10:00:30Z”t Convert “from” to “StartDate” Convert “to” to “Enddate” Convert from XML schema to simple strings expected by MCS

17. Ewa Deelman, www.isi.edu/~deelman Evaluation  Developed a prototype system  Performed queries across data sets from different domains  Climate modeling, earthquake science, workflow execution  Supported temporal queries using the OWL time ontology as the target ontology  Developed a prototype system  Performed queries across data sets from different domains  Climate modeling, earthquake science, workflow execution  Supported temporal queries using the OWL time ontology as the target ontology

18. Ewa Deelman, www.isi.edu/~deelman Discussion  Support only for the query functionality  Need to expand to  data publication  structuring data into collections  Supporting multiple catalogs  Need to support richer catalog structures  Support only for the query functionality  Need to expand to  data publication  structuring data into collections  Supporting multiple catalogs  Need to support richer catalog structures

19. Ewa Deelman, www.isi.edu/~deelman Conclusions  Example of building semantic services on top of legacy catalogs  Provided customized views at the semantic level  Views are customized to a particular user-selected ontology  Need to expand the functionality to publication  Need to address more the handling of alternative data formats  Syntactic versus semantic transformations  Transformations between date/time formats, coordinate systems, etc.  Are these transformations workflows?  Example of building semantic services on top of legacy catalogs  Provided customized views at the semantic level  Views are customized to a particular user-selected ontology  Need to expand the functionality to publication  Need to address more the handling of alternative data formats  Syntactic versus semantic transformations  Transformations between date/time formats, coordinate systems, etc.  Are these transformations workflows?