Modifying session properties dynamically

Z and I Emulator for Web sessions are defined by the administrator and retrieved by the Z and I Emulator for Web client when a user accesses a Z and I Emulator for Web HTML file. The session properties a user sees are fixed values and consist of a combination of the administrator's initial configuration and any user updates. However, there may be times when it would be useful with some HTML files, or with certain session properties, to dynamically set a value at the time that the HTML is accessed. This type of control allows you to set particular session property values based on information such as the IP address of the client or the time of day.

In order to dynamically set session properties at the time the HTML is accessed, the administrator must write a program that runs on the Web server and effectively modifies the HTML just before it is sent to the client. Even though the initial session properties are not defined in the HTML, Z and I Emulator for Web provides the capability to override many of the session properties in the HTML. These override values are always used by the client and take precedence over both the initial session properties setup by the administrator, as well as any updates for the property made by the user. The HTML override value is never stored, so the client will return to using prior settings for the property whenever the administrator removes the override. Also, the overridden property is locked so a user cannot change it.

There are many ways in which an administrator could write a program to dynamically set one or more session properties using the HTML overrides, such as using Java Server Pages (JSP), servlets, Perl, REXX, or Active Server Pages (ASP). This chapter takes you through a couple of examples that focus on common administrator issues. These examples are meant to demonstrate the syntax and technique of overriding particular properties. These mechanisms apply to whichever programming approach the administrator may choose.