Developing Applications with Java™ and UML

Separating Services

Long before distributed applications and the Internet came to the forefront of technology, the layers of an application were thought best kept distinct and separate. Commingling of, for example, the data access and business logic led to “fragile” applications that were difficult to maintain and to understand. However, very few applications followed this approach—until the technology horizon changed and client/server and distributed computing became possible.

The term legacy application traditionally has been applied to mainframe-centric applications. However, many applications built in the past seven or eight years that wear the client/server and/or distributed label are also legacy applications because the logical layers ...