Abstract:
Nowadays, standardized metadata for geospatial data is a key in sharing and finding information on the web and crucial in building Geospatial Data Infrastructure (GDI). The main objective of this paper was to develop a web-based metadata dissemination system for in-situ sensors based on, most importantly, interoperable, standard and open technologies introduced by Open G lS Consortium (OGC), namely Geography Markup Language (GML). In this research, at first a use case diagram was developed to demonstrate the user's requirement. Then, an application XML schema based on user's requirement was created. To build this schema, some GML schema documents (developed by Open GIS Consortium (OGC)) were imported into the application schema. System architecture was designed based on client/server model and a UML class diagram was also developed to present all classes and their attributes, operations and associations within the system Implementation was conducted using GML, XML, XMLHTTP, DOM, ASP, and VBScript that brought out a web-network-based in-situ sensors metadata application. This application provided a user friendly interface to search and find sensor related information. Results showed that although GML and XML are pow eriii1 tools to build geo-metadata, it is important to note that GML document size may be a problem when dealing with huge amount of data.
Machine summary:
System architecture was designed based on client/server model and a UML class diagram was also developed to present all classes and their attributes, operations and associations within the system Implementation was conducted using GML, XML, XMLHTTP, DOM, ASP, and VBScript that brought out a web-network-based in-situ sensors metadata application.
Based on the system requirements analysis, the following XML schema is developed to support the sensor metadata dissemination system.
Since sensor metadata prototype corresponds with server/client model, there are two classes as the following UML class diagram presents: (View the image of this page) Figure 4 Legend of class diagram.
[%%ابتدای جدول%% , , , , , , , , , , , , Client , , , , , , , %%انتهای جدول%%] Figure 6: Relationship between sensor metadata prototype, user, and data provider Based on this design, data provider starts the scenario and using the provider interface, registers the information of datasets metadata in server side XML/GML-based repository.
Next, the server side script retrieves the received information and using the relevant function converts the received information into an XML/GML format (This process is done since sensor metadata repository has been built based on XML and GML data structures).
The following figure shows partially the built XML document for sensor metadata prototype.
Each of these is described in the following: CLIENT SIDE IMPLEMENTATION Based on system architecture, sensor metadata system makes use of XML for sending and receiving messages.