The use of Data-Portal in building Portals / customizing Portals in Pega where in, Instead of generating new sections from scratch, Data-Portal will assist in reusing the default ones. You can set the class to use Data-Portal as the directed parent if you want to use the application-specific data class.
if the customer portal calls for using any of the CaseManager7 parts, such as Recents, Reportbrowser, or the navigation rule used to display the operator menu, using Data-Portal
Another thing to keep in mind is that Data-Portal is the class that Pega 7. x and 8. x uses to design the default shipped portals such as Designer Studio, Case Manager, and Case Worker. However, we can always define harness in the application class if that is what we want to do. The guideline for saving Data-Portal is to aid in the reuse of default sections rather than the creation of custom ones. You can also configure the application-specific data class to use Data-Portal as the directed parent if you want to use it.