![](bg8.png)
the TTL extension, the use of memory is stable,
updated only at regular intervals by the execution of
the garbage collector. This happens because
correlation keys are disposed as soon as a message
that matches the corresponding key is received,
releasing the memory that was occupied by the key.
A similar effect can be appreciated with the
processing time. Figure 8 presents the results of the
delay in the execution of the solver process over
time. Delay without TTL is plotted with a dotted
line, while delay with the TTL extension is plotted
Figure 8: Delay to start the solver with the TTL extension
(continuous line) and without it (dotted line).
with a continuous line. With the no-TLL approach,
every time a message arrives, the matching process
has to consider all correlation keys, including the
values that have successfully matched a message
before. The TTL approach instead presents no delay,
since correlation keys are removed as soon as the
message has been processed, with no need to include
them in the matching process.
6 CONCLUSIONS
Optimization workflows have been used
successfully over many years; however, the
currently available tools used for their definition and
execution are not based on standard technologies. A
large number of different graphic and execution
formats are currently in use, and there is no clear
signs of convergence until to date. This paper has
proposed the use of BPMN 2.0, a well-defined
standard from the area of business processes, as a
formal representation for both the abstract and the
execution model for optimization workflows. In
particular, it was shown that BPMN 2.0 can support
the most widely used optimization patterns required
today in industry. An implementation example that
illustrates the use of BPMN 2.0 extensions to solve a
representative execution efficiency problem has also
been presented.
It is expected that the use of a standard for
optimization workflows will facilitate the
collaboration between scientists and industrial
designers, enhance the interaction between different
engineering and scientific fields, providing also a
common vocabulary in scientific and engineering
publications.
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