Enterprise Geocoding Workshop Architecture and Issues

1. Enterprise Geocoding WorkshopArchitecture and Issues Craig Wolff, M.S. Eng CA Environmental Health Tracking Program Environmental Health Investigations Branch CA Department of Health Services Impact Assessment, Inc.

2. What is Enterprise Geocoding • An address broker that extracts geographic coordinates (lon/lat, region identifier) for multiple users/applications across an enterprise • An address broker provides address standardization/verification, geocoding, and region overlay • Implicit is standards for geocoding and application interoperability

3. Yeah? So who cares? • Geocoding is almost always the first step to linking environmental and health data • Not all Tracking stakeholders have capacity (expertise, data/application resources) or interest/mandate to geocode • Address and geocode quality can increase if it’s done as close as possible to the time an event is reported

4. The Transaction is Everything • Enterprise Geocoding is handled by a unit of interaction called a transaction • Request to server, processing at server, response to client • A request can handle one or many addresses • Server-side processing includes address standardization, verification, geocoding versus multiple street centerlines, and region overlay • Response is the result of the processing

5. Web Services • XML provides interoperability standard for messaging over the Web • SOAP provides an interface to methods that use “serializable” objects. Client and server implementations do not have platform restrictions. (e.g. Microsoft talks to Java talks to ESRI)

6. Serializable Objects • Address – street (prefix, number, street name, type, suffix, etc), zip, city, error (error codes from CASS-certified standardizer/verifier) • GeocodeOptions – Options for how you want addresses geocoded in a session • GeocodeRecord – Processed result of a geocoding transacation • RegionIDs – List of extracted regions for a single geocode

7. GeocodeOptions • int sideOffset • int spellingSensitivity • int minimumMatchScore • int minimumCandidateScore • String [] streetResources • String [] standardizationResources • String [] regionResources • boolean doStreetID • boolean doStandardizedAddress • boolean doRegionID • boolean doZipAsZone • boolean doCityAsZone • boolean doFirstMatchingCoordOnly • boolean doMultiServiceErrorMetrics • boolean doResourceSpecificRegions

8. GeocodeRecord • String [] status (M/U/T) • short [] score (0-100) • String [] side (L or R) • double [] x • double [] y • String [] streetID • RegionIDs [] regionIDs • String [] metadataID • float [] averageError • Address standardizedAddress

9. SOAP Methods • public void initializeGeocode (String user, String password) • public void setGeocodeOptions (GeocodeOptions options) • public GeocodeRecord findAddress (Address address) • public GeocodeRecord [] findAddresses (Address [] addresses)

10. Technologies • SQL Server and ArcSDE for Enterprise GIS • Storage of street centerline and region data • Geocoding engine • Application server for GIS operations • Java Client API for ArcSDE • http://arcsdeonline.esri.com • ZP4 • CASS-certified address standardization • C API • http://www.semaphorecorp.com/cgi/zp4.html

11. More Technologies • Apache Axis • Java-based client/server web services tool • Exposes Java methods and objects on server-side • http://ws.apache.org/axis/ • Apache Tomcat • J2EE application server • Also runs ArcSDE Client API & Axis • http://jakarta.apache.org/tomcat/index.html

12. Even More Technologies • Java Topology Suite (JTS) • ArcSDE Client API bug workaround • More robust spatial analysis methods/objects • http://www.vividsolutions.com/jts/jtshome.htm • Visual Studio .NET, C# • For creating ZP4 web service • For creating web service clients

13. Building a City Geocoding Index • Update street centerline attributes with soundex (zip’s PO name) on left and right • Build geocoding index on city soundex left/right; note: ArcCatalog will overwrite any previous indexes built for the same streets, see http://forums.esri.com/Thread.asp?c=2&f=59&t=96397#271863 for creating a locator using a custom template and command line interface • Pass soundex(city name) from address table • Never accept candidates who have tying score

14. Soundex • Phonetic coding of a word; Geocoders use a 4 character scheme • Codes: • First character in code is same as input • Letters with codes of 0 are not included • Words with less than 4 corresponding codes, receive trailing zeros • Examples Poppy: P110 Oxford: O213 Los Angeles: L252 Santa Clara: S532 Main: M500 Santa Clarita: S532

15. Geocoding in Java • Use ArcSDE Java Client API to communicate with ArcSDE • Use ArcSDE’s Server Side Application (SSA) construct • See http://forums.esri.com/Attachments/6591.pdf for an example

16. Useful Patterns • ArcSDE connections are notoriously slow to initialize  re-use connections from a Connection Factory, and close connections after timeout • Lots of data sources, server names, passwords, etc.  store this info in a database table, create an object that encapsulates data resources; never hardcode • Use Axis/Tomcat sessions to minimize redundant parameter passing • Server: ((HttpServletRequest) MessageContext.getCurrentContext().getProperty(HTTPConstants.MC_HTTP_SERVLETREQUEST)).getSession() • Client: setMaintainSession(true)

17. Client Implementations • .NET thin desktop client • Consumes centralized geocoding service and address standardization service • Input text, Access, or SQL Server table of addresses • Requires Windows and .NET Framework • Browser-based HTML thin client • Better compatibility • More effort in inputting addresses • Easier to couple with environmental linkage services

18. Future Steps • Tools developed thus far address automated geocoding  still need tools for interactive geocoding on a map with orientation layers • Many map services (some free) from USGS, Google, Microsoft that layer vectors and imagery in basemap • Need quicker geocoding engine (commercial service? Centrus?) • Need less cumbersome address standardization service (USPS?)