Benefits and Concerns when Constructing an Enterprise-scale Geodatabase Larry Theller, presenter Agricultural and Biological Engineering Dept Purdue University Co-authors: Bernie Engel, Richard Farnsworth, Jin Yong Choi, Dwight Welch

Background  Campus has 125+ ArcGIS users  My dept. provides GIS data for many groups who use same layers  First step was FTP/download site for 1998 orthos and statewide topo map layer.  Statewide DEM, NASS, 2003 orthos…

Our solution  SDE Geodatabase to act as library  Mostly static layers, users not editing  Fast raster delivery is critical  Off-campus use is a plus  Clients will be various GIS programs

The Geodatabase  ArcGIS native data format  Stores feature classes that have one geometry type  Can store feature and attribute behavior  Spatial and attribute data stored in RDBMS  Two physical implementations –Personal geodatabase –ArcSDE Geodatabse

Capabilities of Enterprise Geodatabase  Rule-based, Enhanced (network) topology  Multi-user (versioned) editing  Attribute validation (domains, subtypes)  Scaleable storage solutions  Referential Integrity in relationships  Custom features ( behavior of objects)

When do you need Geodatabase?  Raster data access drives ours –Can’t afford to move aerial photography  150 casual users storing multiple copies of data.  We use distributed GIS client but with limited WEB access –So want one-stop data access –but…restrict “download” of some data

Purdue’s IT group now offers ArcGIS on Citrix This increases the need for “one-stop data shopping”

Most basic use is container for Rasters and Vectors

Just SDE? Or add IMS?  Physical overhead of SDE database connections versus cost of ArcIMS license.  Will the database be the sole source? -Will you need to interface files (images, changing vectors) with geodatabase features?  Consider AXL service in ArcIMS.

 An ArcIMS Feature Service streams the actual data features to you over the Internet, similar to the way audio and video are streamed. Each feature service contains one or more ArcIMS feature classes. feature classesfeature classes  A layer based on an ArcIMS feature class works the same as any other feature layer. An ArcIMS feature class is simply another feature data source for a layer, just as a shapefile is a feature data source for a layer.  If you add an ArcIMS Feature Service to ArcMap, you'll get a new group layer containing one sublayer for each of the feature classes in the service.  As its name suggests, an ArcIMS Feature Service cannot contain raster data. ArcIMS Feature Service

Client Software Browser/viewer  ArcExplorer 9  WMS viewers  IE (thin client) Full-feature GIS  ArcGIS  Custom Models

Client Software Browser/viewer  ArcExplorer 9 –free –No images from SDE direct –No metadata –Will support images from ArcIMS AXL  WMS viewers –User must customize Full-feature GIS  ArcGIS –Direct Connect –ArcIMS connect –Metadata from SDE –Steeper learning curve –price

 Goal: meet or exceed performance of network-based files

Direct Connect to SDE SDE Database ArcCatalog One connection per client ArcMap Issues on Windows XP

ArcIMS as broker to SDE SDE Database ArcCatalog ArcIMS Feature server Image Server ArcCatalog ArcIMS uses 4 connections regardless of client load. ArcMap

Using ArcCatalog “Add GIS Server”

Add URL of ARCIMS server NOT WEBPAGES!

You can get a list of Feature Data Sets. Each dataset may contain many feature classes. Restricted services are supported.

AXL-based services look like other map layer types to Arcmap, ArcCatalog and ArcExplorer

You can Drag-and-Drop into ArcMap.

Legends are delivered by AXL file.

Groups of layers (“feature datasets” and raster layers) within the geodatabase

Metadata

Metadata  ArcSDE – database has one format for direct connection  ArcIMS –axl service uses different format than web service  ArcIMS metadata server is still another different entity  ArcExplorer – can’t see anything but an embedded url. –Updates must cascade through different file formats and software products. –Needs (!!) to be streamlined by ESRI.

Metadata process  Import into SDE for ArcCatalog  Employ XML version for ArcIMS Metadata server to enable searching.  ArcExplorer users – can export a URL from an attribute - with poor results.  Provide in HTML for ArcIMS web thin clients.

SDE Connects to ArcIMS SDE Database ArcCatalog ArcIMS Feature server Image Server ArcCatalog Web Browser ArcExplorer ArcIMS uses 4 connections regardless of client load. ArcMap Web Browser AXL Services HTML services

Drawbacks of this approach  Design of master GDB is complex.  Requires database management experience (not as much GIS.)  Thin client (IE) aspects not robust.  Metadata: 3 client types, 3 separate copies!  Data presentation not uniform.  ArcIMS components add labor. –Requires more management than static GDB.

Conclusions  SDE Geodatabase is MUCH faster access to raster data than MrSid.  ArcIMS is key broker for multiple client TYPES.  ArcIMS adds significantly to management load.  Future development will be in ArcGIS Server (split-off thin client.)

Lessons  Create metadata for all layers, in XML and HTML.  Import Metadata to SDE from beginning  In retrospect, flat feature tree would be preferable.  Oracle’s unlimited table size is a plus.

Enterprise Geodatabase?  Raster and Vector?  Who is software client? –Full capability with all users? –Or are some just browsers  Will we allow multiple edits?  Read the books or buy training?  Which database? SQL or Oracle?  Who trains “shapefile” users? Questions we asked