There must be a database access component that causes values from any kind of database to materialize as objects inside the business component. Whether object-oriented, relational, or other database access is required, a set of class libraries designed to automate this interface will result in a major savings in development resources. An Order Entry business object will typically have multiple user interfaces. A clerk may be taking the order over the phone, entering purchase information, validating customer records and credit data, and reviewing an order for consistency and customer acceptance. Other users may require different presentation screens.
User interfaces are difficult and time consuming to build at the code level.
Today, much of this process can be automated. They should be encapsulated as separate objects that communicate by message passing to the Order Entry object. Failure to do this will limit reuse and waste valuable programmer time on laborious, time consuming maintenance tasks. Users should be able to create interface objects with simple object-oriented tools. Subsequently, the programmer should be able to easily snap user interface objects onto the Order Entry object.