3-tier architecture

Why do we use three tier arc开发者_如何转开发hitecture?

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Here are a few possible reasons: client/server doesn't work well over the Internet, doesn't scale as well, and is harder to secure.

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In the web development field, three-tier is often used to refer to websites, commonly electronic commerce websites, which are built using three tiers:

1. A front-end web server serving static content, and potentially some are cached dynamic content. In web based application, Front End is the content rendered by the browser. The content may be static or generated dynamically.
2. A middle dynamic content processing and generation level application server, for example Java EE, ASP.NET, PHP platform.
3. A back-end database, comprising both data sets and the database management system or RDBMS software that manages and provides access to the data.

The End-To-End traceability of n-tier systems is a challenging task which becomes more important when systems increase in complexity. The Application Response Measurement defines concepts and APIs for measuring performance and correlating transactions between tiers.

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To keep the Internet away from machines that have no business being there.

Internet | Firewall | Load Balanacer | switch | <-> Web <-> Application <-> Database