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Operational Metadata Framework for Distributed GIServices on the Internet

This presentation explores the use of operational metadata to manipulate geospatial data and bridge the gap between distributed GIS databases and services. It highlights the benefits of operational metadata and provides examples of its implementation.

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Operational Metadata Framework for Distributed GIServices on the Internet

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  1. GIScience 2002, Boulder, Colorado An Operational Metadata Framework For Searching, Indexing, and Retrieving Distributed GIServices on the Internet By Ming-Hsiang Tsou Department of Geography, San Diego State University E-mail: mtsou@mail.sdsu.edu

  2. (A Movie Presentation) • Manipulate huge volume of geospatial data and images on the Internet • Bridge the heterogeneous environments of distributed GIS databases and services • Provide users and computer systems with the semantics and syntactic of GIS data objects. Why Operational Metadata?

  3. The Definition of Operational Metadata Metadata is the information which can facilitate users or computer systems to access, archive, and manipulate centralized or distributed information services, including data objects, software components, and web services.

  4. Data 1 Metadata (Descriptive) Metadata Record #1 An Operational Metadata Scheme Object (Operational) Metadata Record #2 Metadata Record #3 Data Object, Software components, or Web Map Services Data 2 Relational Metadata Scheme Object-oriented Metadata Scheme • Flexible metadata format and update • Protection against metadata loss • Automatically inherit parent metadata

  5. Geodata Object (Shapefiles, DLG…) Metadata Software Component Metadata (Java Applets, .NET object) Web Map Services Metadata (ArcIMS, MapGuide…) The hierarchy of GIServices metadata GIServices Metadata UML notations Generalization UML: Unified Modeling Language

  6. The Design of Operational Metadata GeoData Object Map Browser Java applet Metadata GIS-operation requirements (A, B) (A, B, C, D, E, F) System metadata Integrating Metadata describe how the objects should be represented (color, symbols) and the domain of the object (vector, line, transportation). Other GIS components Self-describing, Self-managing map layers

  7. Operational Metadata Example • Sd_pointofinterest • Metadata: • Date Type: Point • Predefined Symbols: star • Display color: red • Display Size: 7 point for PC, 3 points for PDA. • Scale threshold: 1:20,000- 1:10,000 Internet Map Viewer can retrieve the operational metadata from data objects and apply it on map display.

  8. Geodata Objects (GIS Databases) Operational Metadata Map Display Metadata Descriptive Metadata: Identification, data quality, spatial reference… Spatial Query Metadata Spatial Operation Metadata Data Connectivity Metadata GeoData Object Metadata How to manipulate and access geodata across different environments and devices (color scheme, query languages, access methods for different bandwidths)

  9. GIS Software Component (Programs) Operational Metadata GIS Data Input Requirement Descriptive Metadata: Identification, licensing agreements, distribution information. GIS Data Output Specification Run-time System Requirement Component Registration GIS Software Component Metadata How to invoke / execute GIS programs across the networks, and what are the requirements for data input/output.

  10. Web Map Services (XML documents) Operational Metadata Access Methods Descriptive Metadata: Identification, spatial reference, … Display Type Map Capability Map Theme (Lists – table of contents) Web Map Services Metadata How to display web map services on the Internet and the related GIS analysis capabilities.

  11. Union Operation (Java Apples) GIS Data Input Requirement Acceptable GIS input format:DLG, Shapefiles, Arc Coverage. Prerequisite: coordinate systems Component category: overlay An Union Operation Example Flood, Boulder Land use, Boulder Spatial Operation Metadata Spatial Operation Metadata Associated operation:overlay, hydrological modeling Data format: Arc Coverage Operation logs: 12-3-2001, clip, [Flood areas, USA]. Associated operation:overlay, buffer Data format: Shapefiles Operation logs: Null Criterion-A Spatial Operation Metadata Associated operation:overlay, buffer, hydrological modeling. Data format: Shapefiles. Operation logs: 6-7-2002, union, [land use, Boulder] and [Flood, Boulder].

  12. Metadata Framework Implementation • Digital Library Approach • A centralized metadata database • Relational database engine (SQL Server, DB2, ACCESS) • Metadata as records • Server-side operations. (query and retrievals) • Data Clearinghouse Approach • Distributed metadata repositories (multiple metadata databases) • Metadata Search Engine (Z39.50 – ISITE) • Metadata as XML or HTML documents. • Collaborative operations. (both the clients and servers)

  13. Alexandria/California Digital Library http://webclient.alexandria.ucsb.edu/ Centralized Databases

  14. FGDC NSDI Clearinghouse http://130.11.52.184/FGDCgateway.html • Step 1: Prepare your clearinghouse site and metadata documents and install the ISITE software. • Step 2: Register your clearinghouse site to NSDI • Step 3: The Gateway Engine will put the new clearinghouse site on the LIST of NSDI Clearinghouse. • Step 4: People can query the metadata via the NSDI Gateway.

  15. Clearinghouse Search Mechanism Web browser (Users) Query: “San Diego” FGDC Entry Point (Z39.50 Gateway) NOAA Clearinghouse node (ISITE – Isearch) San Diego State University Clearinghouse node (ISITE – Isearch) ESRI Geo Network (Other search engine) NOAA Clearinghouse node (ISITE – Isearch) NOAA Clearinghouse node (ISITE – Isearch) Metadata File (SGML) Metadata File (SGML) Metadata File (SGML) Metadata File (SGML) Metadata File Metadata File (SGML) Metadata File (SGML) Metadata File (SGML)

  16. NSDI Search Results Problems: all nodes on the same level, lack of integration

  17. AlternativeFramework:Hierarchical Metadata Repository California Atlas Metadata Repository Register Los Angeles Atlas Metadata Repository San Diego Atlas Metadata Repository Register Register Los Angeles Roads (Metadata) San Diego Land use (Metadata) San Diego Roads (Metadata) Similar to the DNS (Domain name systems)

  18. Hierarchical GIS Component / Web Services Metadata Spatial Analysis Tool Box Metadata Repository Register Location Analysis Tools Metadata Repository Hydrological Modeling Tools Metadata Repository Register Register Buffering Function (Metadata) Contouring Function (Metadata) TIN Model (Metadata)

  19. Discussion and Future Development • Semantic Search Mechanism: [San Diego Roads]  [California Roads] “San Diego is part of the State of California”. (Metadata ontology). • Metadata Search vs. Data Attribute Search (San Diego International Airport) • Standardization vs. Flexibility • New technologies, new frameworks.

  20. SUMMARY Traditional Metadata • Designed for centralized, closed GISystems • Descriptive • Too complicated, too many fields • Not machine readable Operational Metadata • More appropriate for on-line GIS applications • Operational • Object-oriented and flexible • Machine readable, self-describing, self-managing

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