Open standards for GIS from an utility perspective

Open standards for GIS from an utility perspective

Robert Carroll
Hitachi Software Global Technology
10355 Westmoor Drive, Suite 250, Westminster, CO 80021

Many current GIS projects were developed on proprietary, closed systems and designed to meet the functions and requirements of a particular department. The challenge for utilities now is how to preserve legacy GIS investments while leveraging new technologies. This paper will review current technology standards including Open GIS Consortium and XML; present how a large utility implemented these technologies while maintaining a legacy GIS; and review the pitfalls and benefits of this GIS implementation approach.

Why Make GIS Open?
All technologies follow a uniform product development process that starts with start-up companies developing concepts into products for early adopters through to established companies mass-marketing technologies. This process has impacted technologies from the automobile to home electronics. But why make a technology open? Well imagine if VCR vendors developed their own proprietary cassette format. Video rental stores would need to stock many different tape formats of the same movie, resulting in increased user complexity, risks, and costs.

Open standards for GIS help organizations to support the understanding and usage of geographic information by increasing availability, access, integration, and sharing of geographic information and enabling interoperability of geospatially enabled components.

These standards allows users to (a) find information and processing tools when/where needed; (b) to understand and employ information and tools independent of platform and location, and (c) evolve GIS environment along the commercial mainstream without containment by a single vendor's offerings. This also eases geospatial infrastructure creation on local, regional, and global level through seamless data sharing and fosters competition at the component level.

What is Wrong with Commercial-Off-The-Shelf Standards (COTS)?
One vendor develops many proprietary standards, which are then adopted by other competitors causing the standard to become “ad-hoc”. While “ad-hoc” standards facilitate system interfacing, they remain the property of a third party organization and not that of the public’s.

Another drawback of these standards is that they are controlled by a third-party provider and can only be changed in format or functionality by that provider. In addition, vendors have embedded hidden features and functionality in their standards, which create an noncompetitive marketplace.

Licensing of the standard’s intellectual property is the major concern with proprietary standards. Formats and data schemas are owned by a vendor and may need to be licensed by other suppliers or end-users (i.e. GIF and Unisys LZW Patent).

Who Defines GIS Open Standards?
There are numerous organizations that have developed a GIS standard. These vary from government departments, such as the United States Geological Survey (USGS) and the Census Bureau, to international groups like the United Nations. With more than 30 groups developing GIS standards, duplicate and competing standards are the norm. However, two organizations have emerged as influential leaders in defining standards: the Open GIS Consortium (OGC) and the International Standard Organization (ISO).

The Open GIS Consortium is an alliance of more than 220 members that include government agencies, educational institutions, Independent Software Vendors (ISV), and end-users. Several membership levels are available: from associate to technical, to principal and strategic. The OGC offers a unique interaction between competing vendors and the user community, providing a robust collaborative environment for standards development.

While the Open GIS Consortium is an organization dedicated to GIS, the International Organization for Standards (ISO) is dedicated to all standards. The TC 211 initiative aims to establish a structured set of standards for information concerning objects or phenomena that are directly, or indirectly, associated with a location relative to the Earth. While these two organizations appear competitive, they have established complementary relations and compatible standards.

OGC Implementation Domain of Services
The OGC has defined its standards domain to include more than simple data interchange. Many people misunderstand this point and interpret OpenGIS as a data format. In truth, OpenGIS standards expand interoperability and system interfaces.

There are four key areas of services within OGC’s domain: core, web mapping, location, and geospatial fusion services. Core services focus on interfaces that are required by all geospatial applications and business domains, such as coordinate transformation. Web mapping services enable the dynamic query, access, and combination of different spatial information through the Internet, such as Web Map Server. New service areas include location (OpenLS), which defines a consistent communication of location/time and route and geospatial fusion services and the combination of non-map spatial information storage like address geocoding.

Current OGC Standards

OpenGIS Simple Feature Specification (SFS)
OpenGIS Simple Feature Specification defines open interfaces that enable communications between geospatial systems of simple vector geometries. Systems compliant to this standard enable disparate systems to communicate geometry, spatial reference, and feature properties information.

OGC anticipates that virtually all geoprocessing software vendors will incorporate SFS within their GIS server and client software programs. This will enable all vendors’ software to work with data from other vendors’ systems. Enterprise data is accessible by any application from any vendor.

Simple Features support geometry types including points, lines, linestrings, curves, and polygons. Each geometric object is assigned a spatial reference ID, which can be different from other geometric objects. The API provides rich functionality by including publishing, storage, access, and operations functions for geometric objects.

SFS has great potential benefits for utility organizations for data sharing and work flow reorganization. For example, a construction contractor would have the ability to remotely connect to a utility engineering department’s GIS server via the Internet in order to access work plans and update as-built features like poles. With SFS the contractor does not need to use the same software as the utility and can select the software based upon application needs.

OpenGIS Grid Coverages
While SFS defines standards for geometric objects (vector), the Grid Coverage Specification provides interoperability between systems that create or use imagery. This includes remote sensing sources (aerial and satellite imagery), terrain models (digital elevation model), and raster maps (scanned).

This specification provides interfaces for image access and basic analysis. Software from different vendors can query each other over the network to access data. The specification utilizes the GeoTIFF file format, standard grid geometries, and SFS spatial referencing. Applications of Grid Coverages for utilities include externally-storing data access; automatically loading the latest satellite imagery from the imagery vendor’s server for a particular project area; and publishing data, which provides network map raster map access to facility locating staff.

OpenGIS Coordinate Transformation Services
The Coordinate Transformation services provide a standard way to access geodata stored in heterogeneous coordinate systems across a network and adjust the map data so that it will geometrically overlay to the same spatial reference system. This has extended and replaced the 2D reference system defined as part of the SFS and defines a standard way to express spatial coordinates for points in 2D, 3D, and 4D (temporal coordinates) coordinate systems.

The European Petroleum Survey Group (EPSG) maintains a registry of the most common coordinate reference systems and transformation parameters and was the starting point for the coordinate transformation specification. The standard includes projections like Universal Transverse Mercator (UTM) and State Plane, datums like North America Datum 1983 (NAD83), and units of measure like meters and US Survey Feet.

OpenGIS Geography Markup Language (GML)
GML is an extension of eXtensible Markup Language, defined by the World Wide Web Consortium (W3). It enables the encoding for transmission and storage of geographic information and is based upon the simple feature specification geometry types and models.

While GML is a very flexible solution, it is well positioned as an open data exchange standard for transmitting small to medium-sized volumes of data. This standard has been widely adopted by many vendors. GML is limited by design and requires other specifications to be implemented, including style definition and communications protocols.

OpenGIS Web Map Server (WMS)
WMS is an interface specification providing uniform access for web clients to maps rendered by Internet map servers. The specification enables the dynamic construction of a map as a picture, answers basic questions about the content of the map, and informs other programs about the maps it can create.

The specification allows web clients and servers to create and display superimposed maplike information from multiple remote heterogeneous sources. This allows the end user to query different web map servers based upon their information requirements rather than access published web maps.

Utilities can use WMS to publish organization specific information like service calls and combine other public data sources like weather data. This allows the utility to focus on its data only.

OpenGIS Web Feature Server (WFS)
WFS extends the concept of the Web Map Server from image-based to feature or vector information. This specification incorporates SFS features and uses GML for transportation.

Web clients request geodata from web spatial data servers. The WFS servers return feature sets as GML for the client. This supports dynamic data access to features including geometry and attributes. Clients can modify rendering styles and views (pan and zoom) on the queried local features without additional server requests. Feature manipulation interface is also supported, including create, delete, and update features. This enables simple data editing and creation through a web client.

WFS provides a richer functionality than WMS and can be used by utilities to support robust data access (such as rendering wood poles with different symbols than concrete poles) and simple data modification and creation (such as facility as-built redlines). Related Open Standards

While the OGC has defined open standards related to GIS, other standards for system interoperability including the Java environment, XML, and open source Linux operating systems have also been evolving. The benefits of these open systems include “Write once, run anywhere”, simplified system architecture, and improved system reliability.

The MultiSpeak Initiative is a group of more than 40 software vendors and consultants, the Cooperative Research Network (CRN), and National Rural Electric Cooperative Association (NRECA) that has developed a specification for system interfaces between utility software applications.

MultiSpeak Standard
MultiSpeak allows each vendor to develop its own interface to a single data integration standard. New interfaces do not have to be written for each software vendor or rewritten for future software releases. This approach increases software application integration within a utility while reducing integration costs. It also reduces interface development efforts and costs for vendors.

The MultiSpeak specification consists of a data dictionary and interface specification. The data dictionary defines 31 common utility data entities and attributes. The data dictionary is not intended to be comprehensive of all utility information, but rather information that can be usefully exchanged between software applications within a utility.

The second part of the specification is an interface specification including a process model. The process model defines the primary data store and maintenance methods and which applications need access to that data. This is a flexible model allowing each implementer to choose the location where data is stored and maintained based upon business processes not software requirements. Data is exchanged from the primary data store to other applications through XML.

MultiSpeak supports data exchange between utility applications, including customer information systems (CIS), engineering analysis (EA), geographic information systems (GIS), interactive voice response (IVR), and automated staking.

The Open Standards Challenge For Utilities
While the current open standards offer greater potential for information exchange, system interoperability, and reduced system architecture, there is no clear path from current proprietary systems. While most of the current GIS software vendors claim to be open, they have not implemented these standards within their current software releases. In addition, many utility applications have been maintained for many years on systems that cannot support standards like XML. These conditions limit how “open” the utility’s system can become.

Many organizations that wish to utilize open standards have had to adopt technologies that adapt or transform proprietary data to open standards. An example of this is the development of Java DataBase Connectivity (JDBC) API that allows standard calls like query and update to be handled by legacy, closed database systems. The JDBC adapter then transforms the JDBC request into legacy format and transforms the result to standard JDBC format. The adapter layer allows the new open system to be introduced while the legacy system remains unchanged.

Geometry Adapters for Proprietary GIS Data
An approach similar to JDBC has been developed to support open access to proprietary GIS data through a geometry adapter layer. The Geometry Adapter is an API that lets users access virtually any GIS data source from an Open GIS conformant application server. It provides GIS connectivity to a wide range of GIS database and file datastores. This solution allows existing GIS processes to continue undisturbed while new open standard systems are introduced.

The GeoAdapter layer sits between legacy GIS data stores and the application layer (Figure 1). Clients request spatial data from the application server. The application server confirms the data location and spatial reference system through a catalogue lookup and routes data requests to the appropriate server, including the Geometry Adapter.

Figure 1: GeoAdapter Architecture
The Geometry Adapter receives the data request and transforms the syntax to the legacy system. The legacy system then returns the queried objects in legacy format to the Geometry Adapter. These objects are then adapted to current Open GIS Simple Features and passed onto the application server and clients. The Geometry Adapter also supports feature transactions including modification, creation, and deletion.

Figure 2: Geometry Adapter in Merged Utility GIS
The Geometry Adapter benefits include open standards clients and server support; legacy system and work flow preservation; and improved data flow.

With geometry adapter technology, utilities are not locked into any proprietary architecture and can continue to use their legacy GIS software. The geometry adapter hides the complexity of many GIS data access tasks, performing the processing at the server tier, making the adapter easy to deploy and maintain. Finally, no configuration is required on the client side. All of the metadata and information needed to connect and render the legacy GIS data is defined in the GIS data catalogue at the application server. Zero client configuration supports the network computing paradigm and centralizes system maintenance.

Real World Implementation Case Study
During the past several years, company mergers and market consolidation have occurred within the utility industry. Many of these mergers were based on increased effectiveness through consolidated services. Why have two systems for accounting, customer service, and GIS? But the GIS data is not compatible. New software requires enormous resources to implement and consolidate and forces existing business workflow to be dramatically altered.

(Figure 2). In the past, one of these systems would be replaced by another, increasing consolidation costs and time and creating employee productivity and morale issues. With the Geometry Adapter approach, both utility’s data and systems can continue to function while enterprise users can now access both sets of data through a web client based on Open GIS standards. This approach can be extended to other implementations including business-to-business data sharing and map data publishing.

Summary
Open standards have been developed for the GIS through Open GIS Consortium and Utility applications through MultiSpeak. While these open standard promise interoperability and decreased costs, current software releases do not support these standards and utilities cannot adopt them. The development of the GeoAdapter architecture now enables organizations to continue to use legacy systems while introducing Open GIS standards based systems.

References

OGC Specification Program, 2002 Open GIS Consortium. From PDF published on www.opengis.org
OpenGIS Simple Features Specification, 2002 Open GIS Consortium. From PDF published on www.multispeak.org
OpenGIS Geography Markup Language (GML) Specification, 2002 Open GIS Consortium, From PDF published on www.opengis.org
MultiSpeak General Information, MultiSpeak Initiative, 2002 from website www.multispeak.org