Patterns-Based Engineering: Successfully Delivering Solutions via Patterns

Appendix E. Subsystem Façade Pattern Specification

Context

A set of database-stored business entities needs to be made accessible.

Problem

Database-stored business entities and services need to be exposed to remote clients. However, this could result in a tight coupling between the clients and the business entities, making maintenance or updates difficult. Also, having the database access code mixed with the business code would make the migration to a new database difficult.

Forces

• Simplify the interaction with clients external to the subsystem by hiding the complexity of the internal entities.

• Allow looser coupling with the database provider as data retrieval and updates are abstracted via JPA managers.

• Improve maintenance and portability ...