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2. Architecture of the Visualization WWW server

2. 8. Downloading the VRML world

Once the JAVA front end applet knows that the visualization has been created it will initiate the downloading of the visualization. Since the JAVA applet is running within a WWW browser it can force the browser to download the VRML world. This has the advantage that the visualization will be displayed in the environment defined by the user. Typically the user has predefined plug-ins attached to his WWW browser to deal with VRML world. Thus, the viewing and storage of the visualization downloaded from a WWW visualization server does not require any extra skills or installation on the user's side. The JAVA front end forces the browser to download a dummy URL with extension ".wrl" from the visualization server. Note that this data is inquired from the port of the visualization server and not from the WWW server since the VRML world was never stored as a file (Figure 4). This also ensures that only the sender of the data can retrieve the visualization of his data. The URL scheme is only employed to hide this special communication link from the browser, so that the browser will proceed in his usual manner to display the data once it is downloaded.

The URL get-procedure connects to a port of the visualization server daemon. The daemon then transmits the VRML world. It is important to note that the data is not stored outside the visualization server daemon. It is not written to disc or any other media. The visualization server acts as a simple pipe which receives user data and converts it into visualizable objects in a ".wrl" format. Once the VRML code is transmitted there is no copy of the user's data left at the visualization server.