J2EE Design Patterns

Name

ACID Transaction Pattern

Goal

To perform multiple actions on a set of resources while ensuring that the underlying resources always remain in a correct state (Figure B-14).

Figure B-14. Classes in a managed transaction environment

Participants

Business logic

Provides the application with its underlying constraints and process flow.

Transaction management layer

Provides code for coordinating the business logic and data access logic to ensure that all transactions meet a set of requirements.

Persistence layer

Responsible for storing data in persistent storage, usually (but not necessarily) a database.

Interactions

All business and data-access logic route any changes to data via a transaction manager object. The transaction manager acts as a gateway either to the persistence layer of the application or to the domain object model itself. It is responsible for ensuring that all permanent changes to the data underlying the application are atomic (treatable as a single unit rather than a set of individual changes), consistent (consistent with its business rules and constraints at the end of each transaction), isolated (do not interfere with other simultaneous transactions), and durable (changes made in the course of a successful transaction become part of the permanent state of the system).

Notes

In an EJB environment, the transaction manager is embedded within the application server. When using ...