ESRI, 380 New York St., Redlands, CA 92373-8100 USA • TEL 909-793-2853 • FAX 909-793-5953 Adding Value to Enterprise GIS With ArcSDE April 10, 2003 In December 1999, ESRI released ArcGIS 8.0.1, which was the initial release of a completely new architecture incorporating in a single, standards-based framework, a family of desktop applications (currently ArcReader, ArcView, ArcEditor, and ArcInfo); a development environment (ArcObjects); ArcSDE, an application server that facilitates storing and managing spatial data in a relational database management system; ArcIMS, technology for Internet mapping and distributed GIS; the geodatabase, a sophisticated object model with support for intelligent features, relationships, business rules, and metadata; and the ArcGIS data models, a series of templates for GIS projects for specific industries and applications. ArcSDE is a spatial database application server for organizations that want a fast, scalable, open solution to manage all of their spatial data with the rest of their business data. ArcSDE provides organizations with the scalability, availability (up time), and advanced management features of the leading commercial relational database management systems (DBMS). ArcSDE software's primary role, within ArcGIS, is to facilitate the management and physical storage of spatial and raster data using the standard data types provided by the underlying DBMS. ArcSDE is fully integrated with the complete spectrum of ArcGIS products and the geodatabase. This integration, in turn, provides a straightforward interface for the GIS or IT professional to interact with, and take full advantage of, the advanced DBMS capabilities for storing and managing spatial data. With ArcSDE, these DBMS capabilities are exposed through a simple interface that requires less DBMS experience. In addition, DBMS functionality exposed by ArcSDE is tailored to the needs of the GIS or IT professional who manages and works in a multiuser, enterprise GIS environment. 1. Full support for DBMS vendor native vector data types ESRI's ArcSDE supports all of the currently available DBMS vendor spatial extensions for managing vector spatial data including IBM's DB2 Spatial Extender for DB2 Universal Database, Spatial DataBlade for Informix Dynamic Server, and Oracle 8i Spatial and Oracle 9i Locator and Spatial. ArcSDE offers important additional features not in the DBMS products. 2. Support for additional spatial data types In addition to vector data, ArcSDE provides support for storing and managing raster, survey, CAD, and address data in a DBMS. When ArcSDE is used with a DBMS spatial extension, such as Oracle Spatial, it will extend it to include annotation and raster and survey data support, which would not otherwise be available. 3. Data integrity For most organizations their biggest investment in GIS is in their data, so maintaining data quality and integrity is critical. ESRI's approach is to (1) provide immediate feedback about data integrity to the user at the client application level through a number of different methods, including enforcing topology, networks, relationships, business rules, and attribute domain values, and (2) to implement data integrity constraints in ArcSDE that check and enforce vector geometries before a transaction is completed rather than implement integrity at the relational database level where erroneous data would not be detected until after it has been inserted into the database. 4. Performance and data compression ESRI offers compressed binary storage for Oracle and SQL Server databases. For Oracle the support is offered for two alternative compressed binary vector storage formats, using the Long Raw and LOB binary types. For SQL Server a single compressed format, using the Image data type, is available. These compressed binary formats provide the fastest performance available for Oracle and SQL Server spatial queries involving complex linear and area features. In addition, the compressed binary formats minimize the disk space required for large vector databases, which can result in significant savings for your customers, especially if RAID disk technology with data mirroring is being utilized. 5. Long transaction and version support GIS operations often require that an edit session not be persisted to the as-built database for hours and sometimes for days or weeks. This is because of the complex nature of GIS (for example, designing a new electrical utility network for a large housing development or alternate corridor analysis for a new light railway project) and the fact that an enterprise geographic database often serves dual roles supporting both transactional editing and data loading and query and analysis against the same database instance. These unique requirements of GIS are met by ArcSDE, which supports multiple, parallel edit sessions with an optimistic concurrency model for the longer transactions required by GIS and versions that allow multiple parallel states, historical snapshots, and distributed database support for applications that enable mobile editors to operate for days or weeks disconnected from the network and for loosely coupled replication of ESRI's geodatabase model between organizational units. ArcSDE is unique in that it enables ESRI to offer long transaction and version support for the four leading commercial relational databases rather than potentially locking our customers into a solution that is proprietary to a single DBMS vendor. 6. Common database interface ArcSDE defines a single logical model for spatial data that is independent of the physical representation in the DBMS. Because of the way ArcSDE manages storage in the DBMS, spatial data access is transparent to the client application. Applications developed with ArcObjects, MapObjects or MapObjects—Java Edition, ArcSDE C or Java API, and ArcGIS Server (coming in ArcGIS 9) will run with little or no modification regardless of the underlying DBMS spatial schema. 7. Open, scalable environments ArcSDE supports the popular server hardware environments including Windows NT and 2000, UNIX (HP-UX, HP Tru64, IBM AIX, Sun Solaris), and Red Hat Linux. In addition, ArcSDE operates over any local area, wide area, or wireless Transmission Control Protocol/Internet Protocol (TCP/IP) network. ArcSDE supports the leading clustered server solutions for IBM (DB2 UDB and Informix Dynamic Server), Microsoft SQL Server, and Oracle 8i and Oracle 9i relational databases. 8. Efficient transport mechanism with intelligent, optimized data buffering ArcSDE uses asynchronous, intelligent data buffering to maximize network throughput. Optimized buffering occurs in both client and server processes. The data buffering allows the server task to continue processing feature retrievals while the client task is occupied processing previously transmitted data. In addition, the server task minimizes network traffic by performing all spatial searches locally and transmitting to the client task only the features and related attribute and metadata required by the client application. The buffers are tunable by the ArcSDE system administrator for maximum performance flexibility. 9. Two-phase spatial query Query performance with ArcSDE is enhanced with the use of a two-phase spatial query. The use of a two-phase spatial query reduces the load on the DBMS and improves scalability. With two-phase spatial query, a primary filter permits fast selection of a small number of candidate features that are then passed to a secondary filter. The secondary filter applies exact computational geometry to the candidate feature set and completes the query by selecting the final feature set. 10. Flexible architecture N-tier environment support by ArcSDE allows maximum flexibility in load balancing for increased scalability. Client connection can be made to the host DBMS through an ArcSDE application server, which can either be installed on the same server as the DBMS or on a separate server or a direct connect driver where ArcSDE runs on the desktop computer with the client application without the need for an application server layer. The capability, unique to ArcSDE, of being able to utilize either an application server, direct connections, or both enables an organization to off-load processing from its core database server for maximum scalability, minimize network traffic, off-load processing from the client when lower end desktops are used, or provide ease of administration in clustered fail-over environments. 11. Flexible data models GIS users need common standards to build and share data. ArcSDE supports both a simple relational model of points, lines, and polygons and a sophisticated object-relational model with intelligent features, rules, and relationships—the geodatabase. The geodatabase can be combined with ESRI's ArcGIS Data Models, templates for implementing GIS projects for specific industries and applications. .