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2-4 Basics of wireless GIS network
Internet workstation uses personal computer as a hardware device. This will allow heavy load process to be performed on client side. In other words, Internet workstation will execute user application on client machine based on distributed (Thick client) architecture, and will lower the workload on server machine.

But referring to mobile devices restrictions most of process load must be taken by server. On the other hand, mobile device only supports input/output process on the terminal, while application programs are stored on server side (Figure 2).


Figure 2: Distributed GIS (Wired and Wireless)
3. Spatial Data
XML is going to become an appropriate and reliable data content, in all services working with portable data. XML is a portable, text-based way of representing structured data [URL 2]. More and more applications are using XML to exchange information and wireless technology is going to need to process XML documents.

With any XML grammar, consideration has to be given to what exactly is being modeled. For textual formats, modeling is typically at the level of paragraphs and phrases, rather than individual nouns, adverbs, or phonemes. In recent years, standardization activities have been in vigorous progress to define geospatial data standard. The common discussion between these activities is to define GIS data feature as spatial object in real world such as road, river, house and so on. GIS data is a collection of varieties of feature data and it is better to be described in XML or XML Schema, due to its distributed (through Internet) inherent (Figure 3).


Figure 3: GIS data model
In conventional GIS system, geometry and attribute data are managed separately and linked to each other with unique ID. Although handling vast amount of GIS data, this mechanism enables effective enormous data process, because geometry data processing and text data processing are separately executed on optimized system for special purpose use. In describing feature data, XML encoding is flexible and comprehensible as an advantage point, but XML is weak from the point of data process and data transfer efficiency.

4. Portable Code
Java provides a robust programming language and environment. The mobile device is J2ME enabled allowing for the development of intelligent and thin applications for the devices.

J2ME is a new akin of Java family and a member of Java 2 platform. It specifically is targeted at applications, running on handheld devices. Many such devices have no option to download and install software beyond what was configured during the manufacturing.

J2ME technology addresses the significant number of resource-constrained devices. Unlike desktop and enterprise computers, whose programming needs are addressed by Java 2 Standard Edition (J2SE) and Java 2 Enterprise Edition (J2EE), the devices in the Micro Edition space are significantly varied in many aspects, such as how they perform networking, how they display information to the user and how they accept user input.

With the introduction of J2ME, “micro” devices no longer need to be “static” in nature. Like a web browser downloading Java applets, an implementation of J2ME on a device affords the option to browse, download and install Java applications and content. Small consumer electronics have a way of changing our lives. Mobile phones let the communication when away from home or office. Personal Digital Assistants (PDAs) let the accessing email, browsing the internet and running applications of all shapes and forms. With the introduction of Java for such devices, there is now access to the features inherent to the Java language and platform. That is, a programming language that is easy to master, a runtime environment that provides a secure and portable platform and access to dynamic content.