The Special Role of M&S in Cross-COI Mediation Bernard P. Zeigler, Ph.D., Arizona Center for Integrative Modeling and Simulation and Joint Interoperability Test Command Fort Huachuca, AZ

System Entity Structure The M&S COI has a special role to play in the area of mediation among metadata schemes developed by the various COIs Interoperability among the web services of COIs will require a more dynamic elements and associated simulation interpretations, typical of the M&S concerns Use System Entity Structure (SES) from Theory of Modeling and Simulation The SES is the basis for a methodology, and practical tool set that supports data engineering and modeling of application domains with hierarchical system characteristics It is being applied by the Joint Interoperability Test Command (JITC) to imagery metadata characterization for the some of the sensor products of the National Geospatial-Intelligence Agency (NGA).

SES Overview SES methodology and tool set –Java classes using Sun’s XML classes –develop well-structured, hierarchically composable data models –can be mapped to a variety of legacy formats. Due to its fairly simple axiomatic structure the SES lends itself to tool-supported structure analysis –tools to compute the common elements and substructures of a pair of SES representations. –not as powerful as a full-blown, logic-based ontology framework –it is sufficiently expressive for real application –sufficiently well structured to allow useful tool support.

System Entity Structure – Basic Concepts Entity – a thing in the real world, e.g book Variable – an attribute of an entity, e.g. title Aspect – decomposition, a way to break down an entity into parts or components (entities), e.g., front cover, back cover, pages Specialization – a classification, a way to classify an entity into special cases or subclasses, e.g., genre MultipleAspect – a decomposition into similar parts, e.g. pages Entities alternate with Aspects and Specializations Prunings generate family of pruned entity structures (PES)

Example: SES Representation of Book book contentDec chapters chapter chapterDec explanation theorem proof theorems example physicalDec pages page front cover back cover Aspect Entity MultiAspect genre bio- graphy fiction Specialization physicalDec pages page1 front cover back cover fiction_book page100 pruning

Generation of XML Schema

merge SES merged SES merge PES merged PES Synthesizing Large SESs and PESs From Components

Top Level SES Representation of NITF Core Information Mission Mission Image Aspect Image Aspect Images Image Identification Segment descriptionsGround referenceSensor Image Data Aspect

SES Breakdown of Identification Information Identification Identification Data Aspect Image Sequence Data Aspect Sequence ID ~ISID Original Image Data Image Sequence ~NRG ~NCG ~TRG ~TCG Date/Time Data Simultaneous Collection

Mission Mission Image Aspect Image Aspect Images Image Identification Segment descriptionsGround referenceSensor Image Data Aspect Identification Entity Merged Into Mission SES Identification Identification Data Aspect Image Sequence Data Aspect Sequence ID ~ISID Original Image Data Image Sequence ~NRG ~NCG ~TRG ~TCG Date/Time Data Simultaneous Collection

Advantages of Hierarchical Methodology for Managing Body of Standards Divide and Conquer - Complex standard is decomposed into smaller more manageable pieces Pieces can be developed and maintained individually as modifications are required Builds (merges) can be performed at any time to create current version of overall standard Some pieces can be stand-alone standards under the same or other authorities XML instances of component standards can be merged into larger XML instances of the overall standard.

Approach to Harmonization Multiple legacy metadata formats that partially overlap in their referents Attempt to find as much common core as possible Express common core in SES Expland SES with Specializations to capture non-core elements Re-derive original content of metadata by pruning from master SES

Tools for Harmonization Relational representation of SES Commonality measures Operations to increase commonality Thesaurus

Relational Representation of SES entities SES can be represented as a collection of relations such as entityHasAspect, aspectHasEntity, entityHasSpecialization, etc. as shown. SES’s can be compared on the basis of their relational representation. SES aspects multi aspects specializations attributes entity specialization attributemulti-aspect 0..n 1 aspect 0..n 11..n 0..n 1..n 0..n n

Finding common entities and SES’s entities common entities SES A SES B

Computing Commonality of SES’s equality of subSES below common entity ? SES A SES B subSES below common entity common entity common entity Commonality = fraction of shared entites fraction of shared sub-SES’s

Entity Removal May Increase Commonality House couch removeEntity (“LivingRoom”) House sofa House Living Room Living Room

Name Substitution may Increase Commonality House couch addRename(“sofa”,”couch”) replaceAll() House sofa House couch House couch

Maintaining Thesaurus of Equivalent Names thesaurus thesaurus.xml store in persistent form addRename(“sofa”,”couch”) replaceAll() House sofa House couch transfer pairs apply to SES set representatives for equivalence classes Representatives of equivalence classes are canonical names that will be used as defaults in application to SES’s, thereby providing a standard version of an SES. RepresentativeClass members sofacouch, sofa, divan,.. wallside, wall,… ……

Dynamic SES Need metadata that tracks processing as data is processed through stages Develop dynamic SES that can evolve through transformations Include forward and reverse links for traceability

Dynamic Process Example: Evolution of a Book Book (concept) Book (content description) Book (physical embodiment) Book (re-printings) Book (revisions)

Ex: Representing Versions In SES book contentDec chapters chapter chapterDec explanatory theorem proofexample theorems engineering version – remove all proofs from theorems mathematician’s version – remove all examples from theorems theorem example theorems theorem proof theorems chapterDec

Trajectories in Space of SESs Book SES Book SES’ transformation retain description of transformation to enable reverse traceability Space of SES’s edges labeled by transformations and ancestor links nodes are SES’s derived from precursors

Summary SES is rich enough to support approaches to harmonization and dynamic processing that will be involved in cross-COI mediation Representation as relations allow Java operation and measurement tools Supports alternative Mappings to XML to satisfy different applications

Bernard P. Zeigler ACIMS JITC jitc.fhu.disa.mil Contact: More information:

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