The document summarizes the Testbed-12 Semantic Portrayal, Registry and Mediation Engineering Report. It describes the scope of the semantic registry, mediation and portrayal services. It outlines the semantic registry information model and application profiles for services, schemas and portrayals. REST APIs and linked data representations are defined for the registry, mediation and portrayal services. Portrayal ontologies are enhanced with new symbolizer concepts. Future work areas around SRIM, pubsub/federation and composite symbology are also noted.
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Testbed-12 Semantic Portrayal, Registry and Mediation Engineering Report Presentation
1. 速
Sponsored by
Testbed-12 Semantic Portrayal,Testbed-12 Semantic Portrayal,
Registry and MediationRegistry and Mediation
Engineering Report (OGC 16-059)Engineering Report (OGC 16-059)
101st OGC Technical Committee
Taichung, Taiwan
Stephane Fellah
06 December 2016
Copyright 息 2016 Open Geospatial ConsortiumCopyright 息 2016 Open Geospatial Consortium
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AgendaAgenda
Copyright 息 2016 Open Geospatial Consortium
Scope
Document Outline
Semantic Registry Information Model
Semantic Registry Service
SRIM Schema Application Profile
Semantic Mediation Service
Semantic Portrayal Ontologies
Semantic Portrayal Service
Future Works
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Scope
Semantic Registry Service
Investigate the usage of DCAT to integrate multi-catalogs (CSW 2.0, CSW 3.0, CSW ebRIM)
Design a REST API to access DCAT-related information
Use Registry to register, search and discover Dataset and Services
Use Registry to register, search and discover Schema and Schema Mapping discovery
Use Registry to register, search and discover Semantic Portrayal Information
Semantic Mediation Service
Define CSW ebRIM profile for Schema and Schema Mapping
Integrate CSW ebRIM with Semantic Registry
Define a Semantic Application profile for describing Schema and Schema Mapping
Focus on XML Schemas and XSLT Transformations for this testbed
Define REST API for Semantic Mediation Service to search and discover Schema and Schema
Mappings, perform transformation and validation.
Semantic Portrayal Service
Support of text, point, line and area-based map symbologies
Enhance Testbed 11 Portrayal Ontologies by defining Symbolizers and Graphics Microtheories
Investigate use of Semantic Registry as Semantic Portrayal Catalog.
Define REST API for Semantic Portrayal Service
Copyright 息 2016 Open Geospatial Consortium
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Document Outline
Overview
Status Quo & New Requirements Statement
Targeted Solutions and Recommendations
Semantic Registry Service
Semantic Mediation Service
Semantic Portrayal Service
Appendix A:Semantic Registry Information Model
Appendix B: SRIM Schema Application Profile
Appendix C: Semantic Portrayal Ontologies
Appendix D: Semantic Registry REST API
Appendix E: Semantic Mediation REST API
Appendix F: Semantic Portrayal Service REST API
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Analysis
Standards reviewed:
DCAT, DCAT-AP, ADMS, GeoDCAT-AP, Project Open Data (POD), CSW ebRIM,
ISO 19115-3, ISO 19139
Report of issues found (20+) with mapping of ISO 19139 to DCAT (section
8.4.2)
Major issue with identification of resources
Inability to refer to SKOS controlled vocabularies
Poor service metadata. Lack of standard classification of service types and
description of other REST APIs specification (Swagger, RAML,..)
DCAT is mostly focused on describing Datasets. GeoDCAT-AP provides a
good foundation for geospatial data
DCAT is not sufficient to describe services, schema, schema mappings,
portrayal information => Needs a generalization of DCAT
No well-established REST API for accessing DCAT
GeoSPARQL and Linked Data formats based on RDF/XML and Turtle too
complex for web clients. Needs of JSON and Resource oriented REST API
Copyright 息 2016 Open Geospatial Consortium
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Semantic Registry Information Model
Core Ontology for Semantic Registry
Superset of DCAT
Introduce concepts of Register and Item (superclass of dcat:Dataset), ItemClass
All DCAT terms are preserved (a lot used in srim:Item).
Defined set of core reusable classes and properties
Extensible to define Application Profiles
Application Profiles developed during Testbed 12
Service and Dataset
Schema Application Profile (Schema, Schema Mapping)
Portrayal Information
SRIM introduces the notion of Release (3-layer approach)
Version tracking is using PAV ontology.
Service is a first class object (extension of Distribution)
Introduction of Standard URIs and APIDocument class to describe service APIs
(simplified description of APIs, instead of complex description of ISO 19119).
Appendix A: SRIM Core Ontology.
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REST API
Use for Level 3 Hypermedia REST API
Schema Agnostic (JSON payload)
Definition of Link Relation Types for each Service
Decoupling Service API with Client Ecosystem
Self-describing API and extensibility
Explorable API (HAL Browser demonstrated)
All three Services implement:
Level 2 supports JSON-LD
URL Patterns of REST API are Non Normative
Level 3 HAL+JSON(-LD)
Linked Data (RDF/XML, Turtle, N-Triples)
JSON can be converted to RDF form using JSON-LD
Context.
Hypermedia Application Language
(HAL)
Richardson Maturity Model
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Semantic Mediation Service Requirements
SRIM Profile for schema and schema mapping
Semantic Registry as a service shall interface with the
Schema Registry which enables the discovery of XML
Schemas, transformation logic, and ontologies.
Support of XML Schema and XSL Transformation
Harvesting of Schema and Schema mapping from CSW
ebRIM
Representation of schema and schema mapping using
Linked Data representation
Definition of REST API
Validation of Document against Schema
Transformation from document from Schema A to Schema
B.
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Semantic Mediation Service
Implemented as a client of the Semantic Registry which stores schema
information
Definition of ebRIM Profile for Schema and Schema Mapping
Use of SRIM Schema Application Profile
Schema and Schema Mapping Harvester from ebRIM CSW
Level 2 and 3 REST API (JSON-LD, HAL+JSON, Linked Data Representation)
Provide convenience APIs to access following resources:
Capabilities
JSON-LD Context
Schemas
Schema Mappings
Validator
Transform
SPARQL Endpoint
Copyright 息 2016 Open Geospatial Consortium
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Semantic Portrayal Ontologies
Testbed 11 Portrayal Ontologies limited to point-based Symbols
Focus on Emergency Management Symbologies
Whats new in Testbed 12 ?
Refinement and correction to Style Ontology
Focus on FeatureTypeStyle
Text, Point, Line and Area Symbols
Graphics Ontology
Symbolizer Ontology
Better Alignment with SLD and SE (moved away from ISO 19117)
Use of OpenStreet Data and Style as testcase (see OGC 16-059)
Out of scope for this testbed
Raster Symbolizer
Composite Symbols
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Semantic Portrayal Service
Implemented as a client of the Semantic Registry which
stores portrayal information
Level 2 and 3 REST API (JSON-LD, HAL+JSON, Linked
Data Representation)
Provide convenience APIs to access following resources:
Capabilities
JSON-LD Context
SymbolSets
Symbols
Styles
Symbol Renderer
Feature Data Renderer
SPARQL Endpoint
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Future Works
Best practices for SRIM and ISO 19115 change
modification
SRIM Layer and Map Profile
Pubsub and federation of Registry
Web of Vocabulary Ontology and Service
Application of Shape Constraint Language (SHACL) for
Linked Data
Composite Symbology and alternates renderers for
Semantic Portrayal Service.