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Abstract
This paper describes the challenges and benefits surrounding a web-based data distribution system. Implementing a web-based spatial data distribution can be a challenge, but many organizations are doing it successfully and reaping the benefits. Before enterprises undertake such projects however, they must first allocate time to understanding the quality of their data, and the target audience. Traditionally, it has been very difficult for an enterprise to consolidate its disparate map data into a single, seamless database, and integrate this significant asset into the decision making process. For the past 30 years, organizations around the world have been capturing spatial data digitally in a wide variety of data formats. With thousands of data formats, sharing mapping data is a complete process. Industry sectors, governments, and even departments often work in data formats that most appropriately address their needs. Recent developments in spatial database technology from a variety of vendors are making it possible for organizations to realize the dream of integrated spatial and attribute corporate databases. Although the transition from mapsheet files into a spatial database can be difficult, many organizations are now successfully doing this in order to leverage their significant spatial data investment. This article provides guidance in preparing for such a migration, independent of spatial database type.
Overview
Spatial data is being used by an ever-increasing number of organizations - from city to national governments, and from small companies to large corporations - who all view spatial data as a strategic asset. As spatial data increases in importance, both businesses and governments need to disseminate and have access to the latest data as cost-effectively and as fast as possible.
As the need for spatial data grows, there is also an increasing number of web-based mapping systems that enable users to view data, and perform simple analysis and other basic GIS operations. The focus of these mapping systems was on providing GIs-based functionality over the Internet/intranet; however, the products have a limited native ability to distribute data.
Historically, spatial data has been distributed using physical media; and, since spatial data is voluminous, data providers were often forced to provide the data in a single format and a single coordinate system. As a result, data consumers who wanted the data in a different format or coordinate system had to convert the data either by writing customized software or by using a commercial data translator such as Safe Software's Feature Manipulation Engine (FME) or Blue Marble Geographics' Geographic Translator.
The growth of Internet and web-based technologies provides new distribution possibilities for spatial data users and providers. Web-based data distribution products are now hitting the market, such as Safe Software's SpatialDirect. When you are choosing a web-based data distribution product, you will need to consider some key points to ensure that the system satisfies both your immediate and future needs.
Spatial Database-Based
Spatial database-based systems provide superior performance in addition to the benefits of a Relational Database Management System (RDBMS). While it is possible to distribute data via the web from data holdings that are not stored in spatial databases, spatial databases such as Oracle Spatial and ESRI's ArcSDE, provide much better functionality.
Web-based data distribution systems that are built on spatial databases are also in no way limited or complicated by file boundaries or other tiling issues, that is the complete data holding can be represented as one contiguous dataset. The first generation of web-based data distribution systems often require all the data to be periodically dumped into a proprietary file format. This restricts first generation systems to smaller datasets and to systems that do not require live updates. It also means extra work is necessary since the data has to be copied from the data source to the webbased format on a regular basis.
Open and Standards-Based Architecture
The web-based data distribution system must have an open architecture that enables integration with third-party products and be based on OpenGIS? Consortium (OGC) standards so that it can easily work with other standards-based products. In particular, the web-based mapping server should be able to act as both an OGC Web Mapping Server (WMS) and an OGC Web Feature Server (WFS). The Web Mapping Server specification is the simplest of the OGC Web Services.
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