Another common type of conversion involves moving a GUI application developed with Java or .NET generators in 2 tiers to 3 tiers.
In general, in a 2-tier application the client handles the presentation tier, the business logic, and connects (JDBC, ODBC, ADO.NET) to a database server that provides the data tier.
In a 3-tier application, the client handles the presentation tier and part of the business logic, connects to an application server (http, Corba, remoting, etc.) that provides the business tier and accesses a third tier made up of data services. This 3-tier architecture has several advantages compared to the 2-tier architecture but they are not studied in this document. What is important is to look into the characteristics of this type of architecture and how to develop or convert applications for it.