Repository Pattern

Definition

Mediates between the domain and data mapping layers using a collection-like interface for accessing domain objects (martin fowler).

Applicability

• When you want to isolate domain objects from details of database access code.

Consequences

• Acting like an in-memory domain object collection

• Providing a more object-oriented view of the persistence layer

• A clean separation and one-way dependency between the domain and data mapping layers.

Downsides

• DDD repository is limited to aggregate roots only

• Hides  persistence storage  features behind a repository interface which sometimes is limiting

Sample Code

References

http://martinfowler.com/eaaCatalog/repository.html
http://ayende.com/blog/3955/repository-is-the-new-singleton

Further Readings

http://domaindrivendesign.org/books/#DDD

http://tech.pro/blog/1191/say-no-to-the-repository-pattern-in-your-dal

http://lostechies.com/jimmybogard/2009/09/11/wither-the-repository/