One effective method of software design is to separate the user-interface routines from the business logic routines and separate the business logic routines from the database access routines. This method of designing the application softwareis called three-layer architecture. Three-layer architecture is used for all types of systems, including desktop applications and browser-based applications.

The object-oriented approach to information systems development has a complete set of diagrams and textual models that together document the user's needs and define the system requirements. These requirements are specified by using domain model class diagrams and state machine diagrams to model the problem domain and use case diagrams, use case descriptions or activity diagrams, and system sequence diagrams (SSDs) to model the use cases.