In Composite Application Framework, you can examine an HTML representation of the View Declaration Language (VDL) file loaded in the design canvas. The design canvas Preview tab shows a static representation of the view as it might appear in a deployed application. The design canvas Preview does not include data from user input or from a database. In addition, you should test the view using the external browsers that you expect users to use. You can add external browsers to use for while designing VDL files.