We have a set of declarative
functions that can be seen as a sort of language that describes the data of the problem
and a control function, the engine, that applies certain rules on these data.
This modularization concisely fits the demand of parallelism (a logical operation
in more threads, and correlated operation managed in parallel) and a fine-grained
application design. But, generally speaking, for medium-large applications, organizing
the code in small units may involve a great number of them (processUnit)
and a dependency graph too complex to maintain and evolve.
To overcome these problems, we implemented the concept of ???component.??? The
components are logical structures embedding one or more processUnits with their
dependences, but at a higher level of granularity. The concept of component addresses
a top-down approach to the problem; first, one can individuate the logical
00 Adzic, Fiore, & Sisto
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blocks (components) and the relation between them (dependences), then ???drill
down??? designing and organizing the specific problem in detail using the thin, more
flexible, and near implementation processUnits.
As an example, the whole structure of the application (processUnit, component,
dependence) consists of a set of functions as shown in the following fragment of
code:
.
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