The portal provides the menu access control. It means if a user has no right to operate a
function, the application link is not visible. For example, administrative staffs cannot
execute the Medical Report Review Services in the HSS group; the service links are not
visible to them. This capability is implemented in configuration files. There is a “check”
property for every menu selection item in the files. The property can control the visibility of
menu linkage. This feature will be discussed in details in the “Content of configuration file”
Section.
4.3.3 DDNM design & implementation
NTUH portal site is designed as hierarchical, drop-down navigation menus (DDNM)
(Goodman, 2003), depicted in Figure 3. The web page only displays in groups initially.
Users first select a group; all the function linkages in the group will be rendered. This
approach makes space usage flexibly as well as enlarges the amount of function linkages
effectively.
Hierarchical DDNM is a client side display mechanism, i.e., this feature executes on user
local machine by web browser. JavaScript is a powerful scripting language running in client
browser, and it has been supported by many websites. Therefore, we choose JavaScript to
implement the client side hierarchical DDNM.
Although the hierarchical DDNM solves the spatial problem of displaying a huge amount of
function linkages (URL links), we quickly face another challenge. Because scripts are
executed at client side, the URL link is normally hard coded in the scripts. Any URL link
modification will cause the server side programs be revised. In addition, if the server side
language is a compiling language, i.e., ASP.NET with C# programming language, the
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program needs to be re-compiled and re-deployed. Therefore, the modification of URL link
is time consuming. In order to solve the problem, the URL link should be retrieved at server
side dynamically and not hard coded in scripts.
At beginning, the server side program retrieves URL links from the configuration files
stored in the servers. A complete DDNM web page embedded with JavaScript is
dynamically generated by the server. Afterwards, the client browser executes the scripts and
displays the hierarchical DDNM. Figure 4 illustrates the concepts of dynamic, hierarchical
DDNM. In the diagram, the users initiate requests; according to the selections, the web
server retrieves the associated configuration files and generates the corresponding web
pages, delivers them to the client side. The browsers render the web page and display the
DDNM. Therefore, if the URL links need to be changed, we only modify the contents of
configuration files. The server side program is independent from URL links. Thus, the URL
links variation cost reduces significantly.
Fig. 4. Concepts of dynamic, hierarchical DDNM