Example: Employee Directory

Suppose an employee directory page lists all employees in a frame on the left hand side of the page. The user clicks on an employee name to get employee details in the right frame. To generate an employee detail page, the Web browser issues a request that enters an employee number on the SAP system screen. With this employee number, the HTML page of employee details can be generated. Essentially, all the parameters required to generate the employee detail page are delivered with the Web request.

One of the most common mistakes is to use the input from the Web browser that does not relate to what is currently on the SAP system screen. For example, it would be correct to use employee numbers (which are unique) to request detail information. By contrast, it would be a mistake to pass the line item numbers, as these numbers become meaningless whenever the screen contents change.

For example, suppose the current transaction screen contains all employees whose last names begin with the letter "B". From a detail screen for a "B" employee, the user wants to see all employees whose last names begin with "F". When returning with the browser's back button, the user sees the HTML page with all the employees whose last names start with letter "B" as the page is pulled out of the browser's cache.

If the user now wants to see the details of the fifth employee on the page, what will actually be displayed are not the details of the fifth employee whose last name starts with letter "B", but the one with letter "F". Why? Because the consecutive number of the employee currently on the screen is being used. Currently, the employees whose last name starts with letter "F" are displayed.

To avoid errors of this kind, a unique identifier such as the employee number should be used to display employee details. When identifying variables are used, discrepancies between HTML page and SAP system screen contents do not matter.