Transcript ASM 591F Data Sources

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.
ArcIMS Feature Service

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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.
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.
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
Zoom to county
Local Drive
Zoom 1:24,000
Zoom 1:2500
Zoom 1:24,000
Open map file
ArcSDE
Windows Share
Samba Share
0
10
20
30
40
50
time (sec)
60
70
80
90
Direct Connect to SDE
One
connection
per client
Database
ArcCatalog ArcCatalog
ArcCatalog
ArcCatalog
ArcCatalog
SDE
ArcMap
ArcMap
Issues on Windows XP
ArcMap
ArcMap
ArcIMS as broker to SDE
ArcMap
ArcCatalog
ArcMap
ArcCatalog
ArcCatalog
ArcCatalog
Database
SDE
ArcIMS uses 4
connections
regardless of
client load.
ArcCatalog
ArcIMS
Feature server
Image Server
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
ArcCatalog
ArcMap
ArcMap
ArcCatalog
ArcCatalog
Database
ArcExplorer
SDE
AXL Services
ArcIMS uses 4
connections
regardless of
client load.
ArcIMS
HTML
Feature server services
Image Server
Web
Browser
Web
Browser
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?
Questions we asked
 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?