Page 118 - Software and Systems Requirements Engineering in Practice

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R e q u i r e m e n t s M o d e l i n g
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C h a p t e r 4 : R e q u i r e m e n t s M o d e l i n g 87 87
4.4 Prerequisites for Using MDRE
There are some organizational prerequisites for effective use of
MDRE. These prerequisites are described in the sections that follow.
Modeling Skills Not Readily Available
Our experience with RE projects is that, after training, it takes about
a month of apprenticeship before an analyst can effectively use MDRE
techniques. For an analyst to be a facilitator or lead an RE team, it will
likely take at least six months working with MDRE under an
experienced team leader. These training times are rough rules of
thumb; the actual times depend on the experience and skills of the
staff and the complexity of the domain.
In an ideal situation, at least one of the team members, preferably
the team leader, should have been completely through an MDRE
cycle, that is, through the end product going into maintenance. We
have all had the experience of the “do-it-yourselfer” fixing a washing
machine or a bicycle, and we know that after we are done, we think
to ourselves, “Now why didn’t I do that in the beginning, it would
have made my life so much easier?” The same is true with systems
engineering; often, going through a complete product development
life cycle can significantly change one’s perspective on what is
important.

Inadequate Tooling
Tools for requirements engineering are viewed by some to be in their
infancy. Vendors would have practitioners believe that their
requirements databases will solve all of our RE process problems, but
this is not usually the case. We cannot always do everything with one
tool; for example, consider maintaining cross-database or cross-
document traces. Furthermore, some tools do not scale well; as the
number of artifacts in use increases, the performance and ease of use
of the tool degrades. Also, with the current business turmoil in the
requirements and development tools area, there is always the concern
that a vendor will stop manufacturing a tool being used on an
important project, leaving the user with limited support.

Organization Not Ready for MDRE
When tools are being discussed and an organization frequently asks
“how much does it cost?” that may be an indicator that the organization
may not be ready for MDRE. Tools can be expensive, but the real
question is, “What is the cost/benefit impact of MDRE on the product
life cycle?” Furthermore, the organizational structure may not lend
itself to MDRE techniques. For example, if there are impediments to
cooperation across organizational units, then MDRE may not be
feasible, since business goals need to trace to product features, and