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Developing Wireless GIS: Using Java and XML Technologies
Hossein Mohammadi GIS Dept., Faculty of Geodesy and Geomatics Eng. K.N. Toosi University of Technology Vali_Asr St., Mirdamad Cross, Tehran, Iran, 1996715433 Tel: +98 21 877 0006 Fax: +98 21 877 9476 Email: hoseinmohamady@yahoo.com  Ali. A. Alesheikh Assistant Professor, GIS Dept., Faculty of Geodesy and Geomatics Eng. K.N. Toosi University of Technology Vali_Asr St., Mirdamad Cross, Tehran, Iran, 1996715433 Tel: +98 21 877 0006 Fax: +98 21 877 9476 Email: alesheikh@kntu.ac.ir Mehrnoosh Ghorbani M.Sc. Student, GIS Dept., Faculty of Geodesy and Geomatics Eng. K.N. Toosi University of Technology Vali_Asr St., Mirdamad Cross, Tehran, Iran, 1996715433 Tel: +98 21 877 0006 Fax: +98 21 877 9476 Email: mehrnoosh_ghorbani@yahoo.com 1. Introduction GIS is a powerful tool in decision making and managing processes in all affairs that are dealt with spatially-related data. Stand-alone and wired systems cannot reach life and work demands appropriately, specifically when it is needed to access the system independent from time and location. So, it seems mandatory to move towards ubiquitous systems, which can serve users anywhere and anytime. Manifestation of nouvelle technology of the servers and users overcome the common systems drawbacks. Growing wireless capabilities create new horizons for serving nouvelle application through wireless network. Such an environment imposes a new set of problems for the development and deployment of applications, because it is based on devices far more limited than personal computers. In order to cope with such limitations, several efforts have challenged the construct of complete framework for the transmission of data over wireless network, and into small devices, while removing the restrictions and shortcomings. Additionally, GIS data usually have large volumes, and need modern techniques to be served through mentioned restrictions. Above problems cannot be solved only by providing special interface for handheld device onto conventional GIS. Some characteristics are handed down from web GIS to wireless GIS. On one hand, the mobile devices and the communication system are developing very fast, on the other hand, the related software technologies including XML and J2ME accelerate the development of the wireless GIS. Arriving Java-enabled handheld devices, and feeding newly introduced formats such as XML into Java programs, make new opportunities to overcome the restrictions. In fact, Java acts as portable code and XML is portable data. Benefits of using XML-based data format, is that, it provides an object-based data format, in which each feature can be analyzed as an object or set of objects, independent from other features. Object-based formats make less time taking for communication and less transferred data amount. Developing in wireless Java (J2ME) provides flexibility to adapt many different platforms. Object-based data formats supply a spatially-suited data format. Combination of the two technologies introduces a powerful tool for serving spatial data through wireless network. 2. Wireless GIS Not only GIS experts but also ordinary people tend to access spatial information using wireless environment. With the integration of the new technologies, GISs make new achievements. The development of the handheld devices (such as PDAs, and Java-enabled mobile phones) and internet not only enlarge the applying field of the GIS, but also bring the new opportunity and challenges to GIS. GIS based on handheld devices, Mobile GIS, will become the new branch of GIS and bring the GIS into a brand new world [Yong, 2002]. Despite enormous benefits of using handheld devices; it meets the shortcomings due to wireless network. Mobile devices have restricted memory, less computational power, and there are no clear standards for wireless network, they have also less speed and stability. Additionally, there are no appropriate platform for sending dynamically spatial functionalities in a streaming manner over wireless network, no suitable spatial format due to data program amount restrictions and low capacity of mobile devices. |