The second stage attempts to determine the most appropriate configuration for each
combination of requirements and conditions. This relies on the report file generated as
output from configuration performance evaluation. Unlike the previous phase, where the
evaluation applications are automatically generated by the APSL parser, the responsibility
for creating the fitness evaluation application falls to the protocol designer. For each entry
in the report file, the fitness evaluator has to determine how well every combination of
application requirements is served. Figure 12.6 presents a pseudo code example of the core
fitness evaluator function for requirements of loss, error, delay and jitter. The fitness
evaluation function reads individual records from the report file described in the previous
section. For each report, the configurations performance is evaluated for every combination
of application requirements. Evaluation is performed by a fitness function that must be
defined by the protocol developer. When considering how well a particular configuration
satisfies an applications requirements in a particular operating environment each
combination is assigned a fitness value. The mechanism used to generate this value depends
upon the desired objectives of the adaptation policy. The fitness function used by the
example adaptation policy is based on a weighted sum with two objectives:
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