Data access object

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Data Access Object ( DAO , English for data access object ) is a design pattern that encapsulates access to different types of data sources (e.g. databases, file systems) in such a way that the addressed data source can be exchanged without having to change the calling code . As a result, the actual program logic should be freed from technical details of data storage and can be used more flexibly. So DAO is a pattern for designing programming interfaces (APIs). If a programming language does not allow a separation of interface definition and implementation, a DAO must implement the defined interface immediately.

properties

  • DAOs do not completely abstract access to databases because they are not responsible for transforming the data into the structure of the database.
  • DAOs are each optimized for a special storage medium. This medium is accessed via the API specified or to be implemented by the DAO.
  • DAOs minimize the porting effort of an application when changing the storage medium.

Closely related to the Data Access Object is the Transfer Object design pattern . In cooperation with the DAO, this takes over the transformation of the data coming from the data source into the form required by the application. In object-relational mapping , object-oriented data are transformed into relational form.

Application examples

The pattern can also be found in the J2EE environment. Apple provides a similar concept called Enterprise Objects in the context of WebObjects .

Web links

Design pattern


Gang of Four
Generation pattern

Abstract factory  | Builder  | Factory method  | Prototype  | Singleton

Structural pattern

Adapter  | Bridge  | Decorator  | Facade  | Flyweight  | Compound  word | Deputy

Behavior patterns

Observer  | Visitors  | Interpreter  | Iterator  | Command  | Memento  | Stencil method  | Strategy  | Intermediary  | Condition  | Chain of responsibility

Other
standard patterns
Generation pattern

Multitone  | Object pool

Behavior patterns

Interceptor  | Zero object  | Protocol stack

Other

Business Delegate  | Repository  | Data Access Object  | Transfer  object | Dependency Injection  | Extension Interface  | Fluent Interface  | Inversion of Control (IoC) | Model View Controller (MVC) | Model View Presenter (MVP) | Model View ViewModel (MVVM) | Model View Update (MVU) | Thread pool  | Service Locator  | Registry