Three Tier architecture

In Microsoft Dynamics AX, there is a 3-tier Architecture which are as follows:

1. Database server : The database server contains the table data. 
2. An application object server (AOS) :The AOS is used to execute application objects, such as queries and           classes.
3. A client.  Application objects in the user interface, such as forms and reports, run on the client computer. 

The following illustration shows the three-tier architecture. 

Advantage of Three tier Architecture

1. When you separate the application data from the application objects, it is easier to distribute upgrade versions of your application. This is because you can distribute forms, queries, classes, and reports that are based on the same set of underlying tables without affecting application data. In addition, separating data from other application objects can reduce network load.
2. You can use the AOS for sharing objects and information as an effective tool to increase performance. Microsoft Dynamics AX and SQL server databases can be used together to provide powerful programming languages to validate data and enforce business rules. For more information