Information Technology Reference
In-Depth Information
Recall that a simple process is an abstract process that can be realized in several
manners. The principle of dynamic composition consists in comparing the simple
process with potentially matching services. Alternative services may be generated,
one or more services can be chosen by the developer according the criteria defined
in the method service contexts. This type of composition is specified on the fly and
requires dynamically structuring and choosing services.
6.1 Discovery
This activity consists of goal definition and service matching. During the first iter-
ation, the goal ontology guides the developer in request formulation. Moreover, the
goal ontology allows checking that the formulated request respects the structure of
a goal (i.e. a verb followed by of an object). In the following iteration, goals directly
result from simple processes.
Service discovery consists in comparing the desired goal with the goal of the
method services available in the services base. If the original goal does not corre-
spond to any method service, it is analyzed using the goal ontology and the product
ontology. On the one hand, the goal ontology makes it possible to search services
which have a similar verb with the goal one. On the other hand, the product ontology
enables to analyze the object of the goal. Discovery of services matching the goal
may result in service alternative solutions.
6.2 Composition
The composition activity consists in service selection and service composition.
Discovery of services matching the current goal may result in alternative solutions.
For each solution, service identification description (manner, context and argu-
ments) is available to guide developer's choices. At this stage of the composition
process, the chosen services contribute to the initial request satisfaction. These ser-
vices can be atomic, composite or decisional (i.e. the process part of these services
may be an atomic process, a composite or a decisional process). At this stage, these
services can be composed in order to achieve the current goal of the iteration. The
composition graph is extended with selected services.
6.3 Refinement
Extension of the composition graph leads to process graph refinement. Indeed,
refinement consists in substituting the variation points (or decision points) by the
corresponding execution graphs of the constituent services. For each process within
the services selected in the current iteration, new iterations are initialized according
to different situations:
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