The most important thing you need in order to have a successful vertical migration is an application where it is easy to isolate the implementation of a functional slice of your application. Figure 12-4 shows a typical vertical migration.
Figure 12-4. A detailed look at a vertical migration.
Notice that, in this case, I have rewritten the client using ASP.NET or .NET Windows Forms. I have also reimplemented the business objects associated with that particular functionality as a managed object using an XML Web service or .NET remoting. You can immediately see the potential problems with this approach by looking at Figure 12-5 ...