Java Location Services: Working to Bring GeoSpatial Technology to the Internet

By Carl Reed - article first appeared at Sun's Java Location Services web portal

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Java, XML and the GIS Standards World

The Open GIS Consortium has a mission which envisions the full integration of geospatial data and geoprocessing resources into mainstream computing and the widespread use of interoperable, commercial geoprocessing software throughout the global information infrastructure.

The OpenGIS Simple Feature Interface Specification is the first to be approved and released by the consortium. The term "Simple Features" is a bit misleading, as the specification also covers feature collections, spatial reference systems, geometry operators, and so forth.

Last fall, an OGC project called the Web Mapping Testbed (WMT) was completed. The consortium showed during its WMT demonstration how it is possible to access and use spatial data from map servers in multiple geographic locations stored in multiple vendor formats. A disaster-planning scenario of a hurricane poised to strike Mobile, Alabama was used. A client application was used to display the map and included features such as the ability to zoom into certain areas and highlight strike probabilities. The WMT had six sponsoring agencies. Over 30 vendors participated in the process.

A key background initiative began during the WMT. It was necessary to communicate simple feature geometry structures and their properties across the Internet. XML (eXtensible Markup Language) was chosen as the transport mechanism. The simple feature specification that was implemented was called SFXML. Now, a broader specification based on Simple Features for SQL has been specified. It is called GML, or Geographic Markup Language. Recently accepted by OGC members, GML will provide the communications foundation for accessing and using spatial data across the Internet independent of vendor or platform. The use of XML meshes perfectly with the overall Java strategy. As stated recently in a SUN document:

"Because of XML's standards-based open grammar based on a human-readable text-based notation, it is emerging as the data transfer format of choice for many Web-based applications. This fact has accelerated XML's acceptance. It is quickly becoming obvious that XML has strong potential to fit well in the role of the lingua franca of the world of data interchange."

"XML and Java technology work well together in a multi-tier application for interactions in a loosely coupled, heterogeneous server-to-server environment and between server and client. For interactions between the server and client, XML and Java technology can enable powerful, lightweight solutions. Java technology-based applications deployed as applets can provide client-side search capabilities and customized presentation. XML data sent to the client provides self-describing and structured information that is easier to process, manipulate and filter without requiring numerous trips to the server. XML is a key technology for Java 2 platform developers who are building applications that carry data across networks -- especially in the case of business-to-business e-commerce."

In response to having a standard interface specification for geographic features moving around the Web, a number of vendors have already developed Java client applications that make use of the emerging specification. The challenge is to push the specification and Java-based geospatial applications beyond the traditional GIS markets and into the personal productivity and consumer-oriented markets.

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Contents:

• Introduction
• Why A Java Location Services Web Site?
• Examples of "GeoJava" Applications
• Application Service Provision in Telephony
• Application Service Provision in Utilities
• Java, XML and the GIS Standards World
• In Conclusion: Has Java gone full circle?

This article is the property of Carl Reed - (c)2000. All rights reserved. Any copying or reproduction of the article in whole or in part is strictly prohibited.