Data access object: Difference between revisions

Revision as of 11:49, 26 April 2005

Revision as of 20:39, 5 May 2005

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In [[computer]] [[software]], a '''Data Access Object''' is a [[software component|component]] which provides a common [[Interface (computer science)|interface]] between the [[Application software|application]] and one or more [[data storage device]]s, such as a [[database]] or [[Computer file|file]]. The term is most frequently applied to the Data Access Object [[Design pattern (computer science)|design pattern]].

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'''Data Access Objects''' was also used by [[Microsoft]] (typically abbreviated to DAO), as the name of a library they created based on this pattern.

== Context ==

== Why use data access objects? ==

Access to data varies depending on the source of the data. Access to persistent storage, such as to a database, varies greatly depending on the type of storage (relational databases, object-oriented databases, flat files, and so forth) and the vendor implementation.

The advantage of using data access objects is that any [[Business object (computer science)|business object]] (which contains application or operation specific details) does not require direct knowledge of the final destination for the information is manipulates. As a result, if it is neccessary to change where or how that data is stored that modification can be made without needing to change the main application.

== Solution ==

== ContextLinks ==

Use a Data Access Object (DAO) to abstract and encapsulate all access to the data source. The DAO manages the connection with the data source to obtain and store data.

* [http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html Sun's definition of the Data Access Object pattern]

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The DAO implements the access mechanism required to work with the data source. The data source could be a persistent store like an RDBMS, an external service like a B2B exchange, a repository like an LDAP database, or a business service accessed via CORBA Internet Inter-ORB Protocol (IIOP) or low-level sockets

== sources ==

* java.sun.com