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Scalable and Interoperable Tourism Information System based on the WebGIS
2.2 Prototype Development
This system is based on a three-tier architecture, from top to down, consisting of graphical presentation layer, a structure management layer and database management layer (Figure 1). TATIS web site construction involves three tasks: managing the tourism information presented at the site, managing the structure of the web site, and creating the graphical presentation of the SVG pages in SVG or HTML formats.  Figure 1 Architecture of integration of WebGIS and tourism information system The function of data management layer is to integrate tourism data from multiple, heterogeneous sources into a single semistructured data repository called the data graph. The data graph is stored in a text file in a syntax layer. The data integration part of TATIS is standard: there is a wrapper for each source and specific mediator. Each wrapper translates the tourism data from the source’s logical model to TATIS’s logical model. The structure makes it easy to add a new source only by making the one-time effort of writing a wrapper for that source. The mediator integrates logically the data from several sources and is defined by a query. The function of structure management layer is to manage the structure. Here we construct a site graph that encodes the TATIS web site’s structure using XML and SVG technologies; nodes correspond to SVG pages, or components thereof, and edges to hyperlinks or to component inclusion. The site graph is constructed declaratively by XML query language from the data graph. The function of graphical presentation layer is to describe the graphical layout in SVG templates for end users via the public Internet, which are input together with the site graph into the SVG generator to create SVG files. This layer allows searching for topic-oriented information and route planning information by hierarchical navigation and complex structured searches. The layer represents dynamic and interactive vector graphics using SVG. In contrast to exiting most conventional TISs on the world, this new design poses fundamentally new challenges: The geographic search for tourist objects and dynamically generated tourist maps. TATIS uses SVG DOM standards to interface with Web tools and editor in order to specify mechanisms for querying, processing, and retrieving of data. SVG DOM is an API for SVG documents. The advantages of this approach is that SVG DOM is a platform- and language-neutral interface that will allow programs and scripts to dynamically access and update the content, structure and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented page. |