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190 Chapter 6 The process of interaction design

JAD (Joint Application Development) workshops in which users and devel-
opers come together to thrash out the requirements of the system (Wood
and Silver, 1995). These are intensive requirements-gathering sessions in
which difficult issues are faced and decisions are made. Representatives from
each identified stakeholder group should be involved in each workshop so
that all the relevant views can be heard.

A basic RAD lifecycle has five phases (see Figure 6.10): project set-up, JAD
workshops, iterative design and build, engineer and test final prototype, implementa-
tion review. The popularity of RAD has led to the emergence of an industry-
standard RAD-based method called DSDM (Dynamic Systems Development
Method) (Millington and Stapleton, 1995). This was developed by a non-profit-mak-
ing DSDM consortium made up of a group of companies that recognized the need for
some standardization in the field. The first of nine principles stated as underlying
DSDM is that "active user involvement is imperative." The DSDM lifecycle is more
complicated than the one we've shown here. It involves five phases: feasibility study,
business study, functional model iteration, design and build iteration, and implemen-
tation. This is only a generic process and must be tailored for a particular organization. ~

w closely do you think the RAD lifecycle model relates to the interaction design model
scribed in Section 6.4.1?

Comment RAD and DSDM explicitly incorporate user involvement, evaluation and iteration. User in-
volvement, however, appears to be limited to the JAD workshop, and iteration appears to
be limited to the design and build phase. The philosophy underlying the interaction design
model is present, but the flexibility appears not to be. Our interaction design process would
be appropriately used within the design and build stage.

Figure 6.10 A basic RAD lifecycle
model of software development.