While this is harder to draw and to read, and is based on
restrictions in electronic design that are not present in modeling languages, it may be
hard to persuade users used to Manhattan routing to adopt a simpler approach.
A similar case is the use of curves for roles instead of lines. For some reason this is
generally combined with a dotted or dashed line style, making the diagrams even
harder to follow. Since editing these curves to look as desired is time consuming, and
there is no evidence of any bene?¬?t from them, it is probably wisest to avoid them.
It is also possible to de?¬?ne algorithms for automatic routing of role lines, optionally
also with layout of objects. A good tool will include some automatic algorithms,
although these remain a challenging issue: since the tool cannot know the modeling
language, the algorithm cannot take into account special requirements or semantics of
different kinds of objects and relationships. DSM models differ in this from simple
FIGURE 14.2 Role symbol texts
WHAT IS NEEDED IN A DSM ENVIRONMENT 377
generic modeling languages, for example, where a single kind of relationship forms a
simple tree structure. Any decent algorithm is suf?¬?ciently complicated that writing a
bespoke version for a DSM language is a major undertaking, and the results are
unlikely to be reliably good.
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