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.
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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.
| Tier | Strategy |
|---|
| User interface tier |
- Low state (does not hold much application code state information), unique data stored in cookies or registry.
- Wide variety of low-end servers.
- Minimize downtime by using additional servers.
|
| Business logic tier |
- Web applications, such as the Product Catalog System, Profiling System, and Business Process Pipelines, run on this tier.
- Low state, no unique data, inexpensive servers.
- Minimize downtime by using software or hardware single-Internet Protocol (IP) load balancing.
|
| Database tier |
- Data that Commerce Server uses is managed and stored in the Data Warehouse on this tier.
- System state and data are stored on this tier.
- Minimize downtime by using a clustered or replicated configuration.
|
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