21.3. Iteration 2 Requirements
Iteration 2 of the NextGen POS application handles several interesting requirements:
Support for variations in third-party external services. For example, different tax calculators must be connectable to the system, and each has a unique interface. Likewise with different accounting systems and so forth. Each will offer a different API and protocol for a core of common functions.
Complex pricing rules.
Pluggable business rules.
A design to refresh a GUI window when the sale total changes.
These requirements will only be considered (for this iteration) in the context of scenarios of the Process Sale use case.
Note that these are not newly discovered requirements; they were identified during inception. For example, the ...
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