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One Model, Many Interests, Many Views
Parallel
The next construct is the parallel. In contrast to sequences of functions where the next entity cannot be
executed until the previous one completes, the parallel construct designates that the parallel branches
can be executed concurrently (even though they may interact through triggers). Though termed a
parallel construct, the better description is a “don’t care” sequence – as the creator of the model is
maintaining flexibility in the system design by avoiding specifying required sequencing.
A parallel construct consists of a fork node followed by separate branches that rejoin and terminate at
a matching join node. The construct can contain any number of branches, and each branch can contain
any number and combination of functions and control constructs.
The construct cannot be exited (from the join node) until all branches have completed their processing.
Control is then passed to the next function or construct after the parallel construct.
Select
A select construct consists of a decision node followed by multiple branches that rejoin at a node. As in
a parallel construct, there may be any number of branches, and each branch may contain any number
of functions and control constructs. But in contrast to a parallel construct in which all branches are
executed, with a select construct, only one branch is executed. Thus, the select construct is an exclusive
OR.