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Approach Benefits
uIncludes well-defined set of interfaces between each of the tiers.
ØTo change application servers (Ex. OAS to IIS):
§Code new middle tier to forward request to the
database.
§No need to refactor each page/screen from JSP to Active
Server Page.
ØTo change databases:
§APIs must be implemented in the new database to process
same input parameters and generate
same output format.
§Well defined actions and business rules in a repository
mean that even switching to
a new database will not be that difficult because only the engine that reads from the repository would have to be
rewritten.
ØTo change clients:
§Refactor UI renderer
§Only core code for action processing needs to be
re-implemented.
§Multiple instances used throughout application mean
modifications only need to be
made once for the core renderer.