The end user was thought to
prefer a simpler approach as chances for reuse would not be so common. Also, the end
user would be less experienced and having to understand reuse and model hierarchies
might require learning things that are rarely needed. To outline the content of the
subaction, the language and related tool support were implemented so that the main
FIGURE 5.5 Reusing a model as a subaction
108 IP TELEPHONY AND CALL PROCESSING
contents of the subaction were summarized in the main model within the subaction
object that referred to a subaction model.
5.3.2 Modeling Rules
Along with identi?¬?cation of the modeling concepts, many of the constraints and model
correctness rules were identi?¬?ed. Whenever possible, they were de?¬?ned to be a part of
the metamodel to be checked actively in the course of time. Otherwise they were
supported in related model-checking reports. Figure 5.6 gives an overview of the call
processing language as implemented in the MetaEdit+ tool. The metamodel shows the
modeling objects and their bindings: possible connections via relationship types and
role types.
Tree Structure By de?¬?nition, CPL scripts should never include loops or
recursions. This, however, does not mean that models should always form the
structure of the script. Model elements should be made reusable, and links to already
existing services could be provided to support ef?¬?cient modeling work.
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