WFS-T and Mobile Clients

Abstract

This report presents the techniques used to enable use of Web Feature Service Transactions (WFS-T) from mobile phones. By using these techniques some important aspects for the next generation of mobile phones are proved.

Web Feature Service (WFS) [1] is an increasingly widespread specification for exchange of geographical information. WFS provides the data as vector data, that is textual description in a eXtensible Markup Language (XML) [2] format of the geographic features. WFS is an Open Geospatial Consortium (OGC) [3] specification and current version is 1.1.0. WFS uses a XML based language called Geography Markup Language (GML) [4] to describe geographic features. An extended set of WFS is Web Feature Service Transaction (WFS-T). WFS-T provides a set of operations to perform transactions on features accessed from WFS. The amount of Web Feature Services with transactional support is yet small, but there exists a few implementations within the research and open source domains. Some Web Feature services are also growing up within the Norwegian public sector.

Web Map Service (WMS) [5] is an older specification from OGC. It is well known and is widely provided from an increasing amount of web services. In contrast to WFS, WMS provides map images of the geographic features, not vector data. It is an International Organization for Standardization (ISO) standard under the ISO/TC 211 19128. The WMS standard supports several common image formats.

Thin clients, like mobile phones and Personal Digital Assistants (PDA), are today widespread all over the world. The use of mobile phones and PDAs is growing into new dimensions by the introduction of the next generation of processing capacities, built-in functionality and extended bandwidth. Third generation mobile networks has been introduced in most western countries and many eastern too, and gives the communication speed a great lift. Mobile phones and PDAs have until lately been to poorly equipped to handle WFS. However, modern mobile phones have evolved to a level of maturity which enables them to parse quite large amounts of text from a XML document.

The research in this master thesis is based upon these technologies and tries out the capabilities of modern mobile phones to handle WFS-T. The possibility of combining WMS and WFS to obtain a richer diversity of features in the map has also been looked at. In this work a lot of challenges have been revealed with relation to performance, modularity, user interface, and parsing. First of all, the work shows that it is possible to generate map images from WFS response data and display them on the fly on a mobile phone. Second, it is possible to perform transactions with locking by using the WFS specification from a mobile phone. And third, it is possible to provide the user with properties information of the features from an WFS on a mobile phone. These three aspects can also be obtained within the same application in the same runtime environment, based on current Java 2 Micro Edition (J2ME) technology. The work is based on standard and widely known tools and technologies to support common standards. They are freely available with no charge for non-commercial use.