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This article explores the integration of data, data models, and analyses in a functional system and discusses the challenges and issues involved. It also introduces an XML-based spatial data exchange system for efficient data distribution and customization.
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Bringing “it” all Together !? Dean Djokic, ESRI David Maidment
What is “it” ? • Integration of data, data models, and analyses in a functional system WRAP RAS GIS SWAT MIKE 11 HMS MIKE 21 Other …
Data providers Data consumers (often both) Unspecified at the beginning of the integration exercise Proprietary Independence from integration platform Development out of “control” Maintenance “curse” Complexity increase (multiplicative) Integration Issues
Integration Issues(direct interfacing) N RAS WRAP MIKE 11 SWAT MIKE 21 HMS GIS Other … N * (N - 1) Bi-directional
Integration Issues(intermediary interfacing) N RAS WRAP MIKE 11 SWAT XML MIKE 21 HMS GIS Other … 2 * N Bi-directional
An XML-Based Generic System for Spatial Data Exchange Extension of GOODES approach Dean Djokic, Zhumei Qian, Xinnong Zhou Environmental System Research Institute Redlands, CA
Why XML-Based Spatial Data Exchange • Semantic tags for spatial data are user specified • Easy customization of data structure for different systems • Data structure is extensible • Good for data distribution on Internet (multi-platform) • Existing technologies for XML management (parsers, editors, viewers, components, checkers, converters, …) – economy of development
System Design of the XML-Based Exchange System • Architecture • A central exchange mechanism accompanied by customizable XML structures • Three components • Central data exchange mechanism embedded in GIS (ArcMap-based) • Customizable control XML structure for import • Customizable control XML structure for export
Import Customizable Import XML Structure Import Data as XML Document GIS External Data Analysis Package Central Exchange Mechanism Export Import Engine Export GIS Data as XML Document ExportEngine Customizable Export XML Structure
Central XML-Driven Spatial Data Exchange Mechanism • GIS Import Engine • Transform data from various XML data exchange structures into spatial data in a user-defined data model • An intermediate XML to XML conversion might be required • Input data exchange structure and geodatabase design are managed by import control XML • GIS Export Engine • Transform spatial data from a user-defined data model into various XML data exchange structures • Output data exchange structure and geodatabase design are managed by export control XML
Data Export Process Export XML Structure I • Read XML structure • Determine what needs to be exported • Determine output data structure • Generate output data GIS Export Data I as XML Document ExportEngine Spatial Data I Export XML Structure II Spatial Data II Export Data II as XML Document
A Close Look of Export Process GIS Data Determine Data Structure Output Data Export XML Structure • System reads export control XML • Determines output data structure • Generates output
Customization of Data Export • Customization is via node attributes in control XML structure • Node attributes fall into two categories • Describe data model customization • SourceType, DataLocation, Identity, IdentityValue, and DataFrame • Follow the logic of spatial database (ESRI geodatabase in this prototype) • Describe data representation style • Name, Entries, and Target • Completely user defined
Control XML in Export Process Sample Control XML <Node1 Name=“StreamNetwork” SourceType=“FeatureLayer” Identity=“LayerName” IdentityValue=“Reaches” > <Node2 Name=“Stream” SourceType=“Feature” Entries=“Multiple” > <Node3 Name=“StreamID” SourceType=“FeatureTable” Identity=“FieldName” IdentityValue=“Reach_ID” Target=“Attribute” /> </Node2> </Node1> Sample Output Data <StreamNetwork> <StreamStreamID=“1” /> <StreamStreamID=“2” /> </StreamNetwork>
Read in data Read control XML structure Validate import data structure against the control structure Generate spatial data Store spatial data in a geodatabase Data Import Process Import XML Structure I Import Data as XML Document GIS Import Engine Import XML Structure II Spatial Data I Spatial Data II Import Data as XML Document
Model Connections to ArcHydro TIWSS Texas Integrated Water Simulation System Tim Whiteaker Center for Research In Water Resources August, 2002
Update Curve Number Variety of Models & Input Formats • Record-Parameter List • Modify Particular Records
WRAP Inputs (-SIM, -HYD, CON-SIM) • Brazos.DAT – basic input file • Brazos.INF – naturalized streamflows • Brazos.EVA – net evaporation-precipitation • Brazos.DIS – flow distribution and watershed parameters
InputRecords in GIS • Brazos.DAT • CP Records NextDownID • Brazos.DIS • WP Records Control Point Identifier Drainage Area Curve Number Mean Precipitation
A Central GeoDatabase ~3,316 Control Points
XMLThe Extensible Markup Language A meta-markup language for text documents XML documents with data in strings of text surrounded by text markup that describes the data Users can define the elements they need. In Water Resources elements like Control Points can be defined An XML document can be used as a config file for any program to take action based on it Due to its extensibility & platform independent character XML is being recognized as “The new standard for data exchange”
From GIS to XML Applications to extract GIS data and format it as a XML document, are being develop by ESRI (XML-Based Converters)
Control XML Structure The application extracts the data based on a Control XML file that specifies the data to be extracted and the XML structure in which will be organized
GIS Data with XML Structure After running the application, the extracted data is placed in a XML document from which data can be exchanged with any modeling system by parsing the XML structure
The Document Object ModelDOM • To parse a XML document • To readily manipulate the Data XML document file and retrieve all the needed GIS values • A Visual Basic Application that takes advantage of DOM to retrieve the data and write it back following any format prescribed by any modeling system, e.g., WRAP, SWAT, etc.
From XML to WRAP Exporting Geospatial and Time Series Data into WRAP
WRAP Control XML Root.dis Root.dat New Root.dis GIS Data XML XML 2 WRAP (DOM) XML Converter New Root.dat Generic Data Exchange XML-Based Structure
Example of Input Files Existing Brazos.dat File Existing Brazos.dis File Updated Brazos.dis File Updated Brazos.dat File