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 GIScience 2002, Boulder, Colorado

Why Operational Metadata? (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.

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.

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

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

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

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.

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

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

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

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

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)

Alexandria/California Digital Library Centralized Databases

FGDC NSDI Clearinghouse 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.

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

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

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

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

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.

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