# Architectural Pattern

## 3-Tier Architecture Nest.JS

1\. **Controllers:** A controller’s sole purpose is to receive requests for the application and deal with routes.

2\. **Service Layer:** This part of the block should only include business logic. For example, all the CRUD operations and methods to determine how data can be created, stored and updated.

3\. **Data Access Layer:** This layer takes care and provides logic to access data stored in persistent storage of some kind. _**For our project we are using MySQL.**_

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