The true power of these rather simple models becomes obvious when chaining
several services (Figure 5).
In this example, three input parameters are processed: For a given user (???userID???), a destination
(???destination???), and an indicated price limit (???maxPrice???), first the list of preferred
airports is determined by calling one service, and then the available flights are searched by
calling a second service, and combining both dynamic parameters and results from user
interaction. In this way complex scenarios can be based on a very simple model.
Also the level of abstraction is very high: Assume, for example, that all XML data structures
are connected to an ontology. If service A requires input conforming to ontology oA and re-
Figure 4
B skup, Heyer, & Marx G??mez
Copyright ?© 2007, Idea Group Inc. Copying or distributing in print or electronic forms without written permission
of Idea Group Inc. is prohibited.
Figure 5
Figure 6
Conceptual Model Dr ven Software Development (CMDSD)
Copyright ?© 2007, Idea Group Inc. Copying or distributing in print or electronic forms without written permission
of Idea Group Inc. is prohibited.
ceives its input from a service B which in turn is only able to produce results conforming to
ontology oB the runtime environment can (transparently for the model builder!) search for a
transformation rule oA ?†’ oB and apply it, all this without requiring any in-depth knowledge
of the ???end user??? (the HTML modeler/designer).
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