SYSTEM ARCHITECTURE

Our system design integrates techniques for graphical user interfaces, automatic graph layouts, distributed computing, Internet and web programming, computer networks, and communications.

The architecture for our system includes two major components : a web graph user interface component for generating and adjusting web sub-graph displays, and a dialog component for communicating between the diagram user interface and the WWW.

The web graph user interface component displays web sub-graphs, allows layout adjustment, supports web navigation, etc. As mentioned in the previous section, it provides three kinds of modes for the user's interaction with the web sub-graph: LayoutAdjust, ShowPage and Navigation .

The dialog component supports the construction of web sub-graphs by communicating with web sites over the Internet. It can quickly search the entire neighborhood of the focused node to form a web sub-graph.

The dialog component has a web site parser and an information filter. The web site parser analyzes the HTML file of the web site corresponding to the focused node and extracts the hyperlinks embedded in the web site to form nodes and edges for the web sub-graph. To reduce the complexity of the web graph, the information filter removes unnecessary information (edges and nodes) generated by the parser; it only retains the essential part which the user requires. Then, the web graph user interface component maintains the user's orientation for web exploration, and it also reduces the cognitive effort required to recognize the change of views. This is done by connecting successive displays of the subset of the web graph and by smoothly swapping the displays via animation.

This chapter focuses on introducing layout techniques for the web graph user interface component.