User's Manual

Chapter 9. Persistence Tutorial 67

• SessionManager — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/\ Session-

Manager.html.

This class is responsible for initializing the Session class. Users of persistence will use

it to get a pointer to the Session class through SessionManager.getSession()

(http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/\

SessionManager.html#getSession()).

• Session — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/Session.html

All persistence operations take place within the context of a session. The Session object contains

methods for creating and retrieving data objects, data queries, and data operations.

• DataObject — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/DataObject.html

This interface deﬁnes the public methods for Data Objects; see Data Object.

Data Objects are normally accessed through the use of DomainObjects

(http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/domain/DomainObject.html).

• OID — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/OID.html

This class represents a unique identiﬁer for a given Data Object. It typically holds the information in

the object key (Object Key) of the object type. For the WAF Object type, the OID is the combination

of the "acs object type" (e.g., com.arsdigita.User) and the "object id". This is typically used to

retrieve speciﬁc objects from the database.

• DataQuery — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/DataQuery.html

This class represents an interface for retrieving arbitrary information from the database. It is the

Java equivalent of the PDL data query described in Section 9.4.1 Data Queries.

• DataOperation — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/\ DataOper-

ation.html

This class represents an interface for executing arbitrary DML within the database. It is the Java

equivalent of the PDL data operation described in Section 9.4.2 Data Operations.

• DataCollection — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/\ DataCol-

lection.html

This class is used to represent a collection of data objects. DataCollections can be used to

efﬁciently iterate over a large set of DataObjects and access the values of their properties. These

can be ﬁltered in a manner similar to DataQueries.

• DataAssociation — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/\ DataAs-

sociation.html

This class is similar to the Java Collection interface, in that it provides

methods that act on the entire set of associations, such as add(DataObject

object) (http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/\

DataAssociation.html#add(com.arsdigita.persistence.DataObject)), and

methods that return other objects to access the associations, such as

cursor()(http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/\

DataAssociation.html#cursor()).

• DataAssociationCursor — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/\

DataAssociationCursor.html

Like a Java Iterator, this is used to loop over a set of associations. Developers can also add Filters

to DataAssociationCursors, thereby restricting the objects returned to the desired subset.

• Filter — http://rhea.redhat.com/doc/waf/6.0/api/com/arsdigita/persistence/Filter.html

This class is used to ﬁlter the results of associations and collections. For instance, if a developer

only wants the associated objects with a name starting with "l" then a ﬁlter is used.