To change the appearance of pages of a BSP application without having to modify the layout source code, you can use the theme concept. You create a theme as a separate development object in the Web Application Builder. It serves as a container for all those MIMEs that are changed. Using a theme, you can subsequently replace objects in the MIME Repository by MIMEs from your own PC file directory without having to make changes in the layout source code. A theme object allows you to overwrite the references to MIME objects. You must imagine that several physical objects can exist for one logical object. The physical objects represent different implementations of one and the same logical MIME object and are referenced on the BSP application page using the same URL (see the figure below).
So that the changes take effect at runtime, you must assign only the theme object to the respective BSP application.

As soon as a MIME object is requested by a page, the BSP runtime program determines whether a theme is also assigned to the current BSP application.
If this is the case, there is an appropriate context parameter already set for the respective object in the MIME repository.
On the basis of the context parameters, the system retrieves the required information as to which physical MIME object in the MIME repository is to be used.
The resulting object is displayed by the system on the referencing page when the BSP application is run.

With the assignment of a theme to a BSP application, you can, with little effort, customize the appearance of pages in a BSP application to suit your individual needs.
A typical task could be, for example, designing a company-specific layout in which you wish to do the following:

• Replace the logos, icons, pushbuttons, or graphics on the pages of the BSP application with others.
• Change the formatting of HTML attributes using style sheets.

To use a theme in your BSP application, proceed as follows: