Isolating the Three Tiers
Most Internet services require configurations that separate the user interface tier from the business logic tier and the database tier to simplify administration.
The following figure shows how many e-commerce sites further isolate business logic from underlying data.
In a multi-tiered configuration, such as the one shown here, client browsers access Web pages and the Web pages activate associated business logic hosted on a Web server. The persistent data that the business objects require is maintained in a separate database tier.
Data and state information control processing logic and client experience. The following table describes typical design strategies you can use for isolating each tier.
|User interface tier||
|Business logic tier||
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