This document is entitled A LAN structure and shows the structure of a kind of Local Area Network.

In this document:

An entity called Presentation, which is the presentation part of the drawing, regroups several elements:

• an entity called BigComputer, which represents a Big Computer.
• an entity called MidComputer, which represents a Computer.
• an entity called SmallComputer, which represents a Small Computer.

Moreover, the entity Presentation has on its right an entity called FireWall, which represents a Firewall separating the presentation from the business logic.

The entity FireWall is the convergence point of several elements:

• the entity BigComputer.
• the entity MidComputer.
• the entity SmallComputer.

Also, the entity FireWall is connected with an entity called Engrenages, which IS NOT a Mickey Mouse but rather an allegory of the working processes within the business logic.

The entity Engrenages is part of an entity called BusinessLogic.

The entity BusinessLogic has on its right an entity called Data.

The entity Data regroups several elements:

• an entity called Databases.
• an entity called Legacy Systems.
• an entity called External applications.

Moreover, the entity Engrenages is the convergence point of several elements:

• the entity Databases.
• the entity Legacy Systems.
• the entity External applications.