Model checking was mostly done at modeling
time, but some checking by generators was also found useful.
. The quality of speci?¬?cations was better. The ?¬?rst tests showed signi?¬?cant
decreases in errors and using generators totally removed most typical errors.
5.8 SUMMARY
This ?¬?rst case of DSM creation shows how a language is created based on a wellbounded
domain speci?¬?ed as an XML schema. Schema concepts are mapped almost
one-to-one to language concepts. Thus the modeling language concepts are directly
118 IP TELEPHONY AND CALL PROCESSING
based on the key elements and the structure described in the CPL speci?¬?cation.
Language elements such as Switches, Locations, and Signaling actions and their
attributes are speci?¬?c for processing Internet phone calls and services. These concepts
automatically become familiar to the service developer and they form a
comprehensible working environment for CPL service developers.
The modeling language was built before any CPL servers were implemented, so
the platform was not yet ready. However, the CPL DTD and later the companyspeci
?¬?c extensions allowed building the DSM solution in advance. Adequate
speci?¬?cations of the language enabled this parallel development of the DSM and of
the platform. This case shows that there is no need to wait until the target environment
and platform are ready: DSM can be made ready beforehand.
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