Interface Persistence
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- All Known Implementing Classes:
SQLEngine
public interface Persistence
The persistence engine implements this interface in order to allow objects to be created, removed, loaded, stored, locked and checked for dirtyness.The caller takes full responsibility to assure integrity of transactions and object caching and only relies on the engine to assist in assuring that through the mechanisms available to it.
All method calls provide an open connection into the persistence storage. The connection is opened by and maintained in the context of a transaction. The type of the connection depends on the persistence engine (JDBC, JNDI, etc).
All method calls provide the object fields and the object identity. The engine must always use the identity passed in the method call and never the identity contained in the object itself.
The stamp is an arbitrary object that is returned on object creation and loading and passed when performing a dirty check. The stamp can be used to detect object dirtyness in a more efficient manner in database that support a stamping mechanism (e.g. Oracle RAWID, Sybase TIMESTAMP).
An implementation of this object must be re-entrant and thread safe. It must depend on the connection passed in each method call and never hold a reference to a connection.
- Version:
- $Revision: 8752 $ $Date: 2006-04-26 16:24:34 -0600 (Wed, 26 Apr 2006) $
- Author:
- Assaf Arkin
- See Also:
TransactionContext
,PersistenceQuery
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description Identity
create(Database database, java.lang.Object conn, ProposedEntity entity, Identity identity)
Creates a new object in persistence storage.PersistenceQuery
createQuery(QueryExpression query, java.lang.Class<?>[] types, AccessMode accessMode)
Creates and returns a new query object.SQLRelationLoader
createSQLRelationLoader(java.lang.String manyTable, java.lang.String[] idSQL, int[] idType, TypeConvertor[] idTo, TypeConvertor[] idFrom, java.lang.String[] relatedIdSQL, int[] relatedIdType, TypeConvertor[] ridTo, TypeConvertor[] ridFrom)
void
delete(java.lang.Object conn, Identity identity)
Deletes the object from persistent storage, given the object' identity.void
load(java.lang.Object conn, ProposedEntity proposedObject, Identity identity, AccessMode accessMode)
Loads the object from persistence storage.void
store(java.lang.Object conn, Identity identity, ProposedEntity newentity, ProposedEntity oldentity)
Stores the object in persistent storage, given the object fields and its identity.
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Method Detail
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create
Identity create(Database database, java.lang.Object conn, ProposedEntity entity, Identity identity) throws PersistenceException
Creates a new object in persistence storage. Called for an object that was created during the transaction when the identity of that object is known. Creates a new record in persistence storage. Must detect an attempt to create an object with the same identity and must retain a lock on the object after creation. If the identity is null, an identity might be created and returned by this method.- Parameters:
conn
- An open connectionentity
- The fields to storeidentity
- The object's identity- Returns:
- The object's identity
- Throws:
PersistenceException
- An object with the same identity already exists in persistent storage or any other persistence error occured.
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load
void load(java.lang.Object conn, ProposedEntity proposedObject, Identity identity, AccessMode accessMode) throws PersistenceException
Loads the object from persistence storage. This method will load the object fields from persistence storage based on the object's identity. This method may return a stamp which can be used at a later point to determine whether the copy of the object in persistence storage is newer than the cached copy (seestore(java.lang.Object, org.exolab.castor.persist.spi.Identity, org.castor.persist.ProposedEntity, org.castor.persist.ProposedEntity)
). If lock is true the object must be locked in persistence storage to prevent concurrent updates.- Parameters:
conn
- An open connectionproposedObject
- The fields to load intoidentity
- object's identityaccessMode
- The access mode (null equals shared)- Throws:
PersistenceException
- The object was not found in persistent storage or any other persistence error occured.
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store
void store(java.lang.Object conn, Identity identity, ProposedEntity newentity, ProposedEntity oldentity) throws PersistenceException
Stores the object in persistent storage, given the object fields and its identity. The object has been loaded before or has been created through a call tocreate(org.exolab.castor.jdo.Database, java.lang.Object, org.castor.persist.ProposedEntity, org.exolab.castor.persist.spi.Identity)
. This method should detect whether the object has been modified in persistent storage since it was loaded. After this method returns all locks on the object must be retained until the transaction has completed. This method may return a new stamp to track further updates to the object.If the object was not retrieved for exclusive access, this method will be asked to perform dirty checking prior to storing the object. The original argument will contains the object's original fields as retrieved in the transaction, and stamp the object's stamp returned from a successful call to
load(java.lang.Object, org.castor.persist.ProposedEntity, org.exolab.castor.persist.spi.Identity, org.exolab.castor.mapping.AccessMode)
. These arguments are null for objects retrieved with an exclusive lock.- Parameters:
conn
- An open connectionnewentity
- The fields to storeidentity
- The object's identityoldentity
- The original fields, or null- Throws:
PersistenceException
- The object has been modified in persistence storage since it was last loaded or has been deleted from persitence storage or any other persistence error occored.
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delete
void delete(java.lang.Object conn, Identity identity) throws PersistenceException
Deletes the object from persistent storage, given the object' identity. The object has been loaded before or has been created through a call tocreate(org.exolab.castor.jdo.Database, java.lang.Object, org.castor.persist.ProposedEntity, org.exolab.castor.persist.spi.Identity)
. After this method returns all locks on the object must be retained until the transaction has completed.- Parameters:
conn
- An open connectionidentity
- The object's identity- Throws:
PersistenceException
- A persistence error occured
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createQuery
PersistenceQuery createQuery(QueryExpression query, java.lang.Class<?>[] types, AccessMode accessMode) throws QueryException
Creates and returns a new query object. The query object is used to execute a query against persistent storage and fetch the results of the query. The query parameter types are specified prehand. If a particular parameter type is unknown, null may be used and type checking will defer to query execution.- Parameters:
query
- The query expressiontypes
- List of all parameter types, or null- Returns:
- A new query object that can be executed
- Throws:
QueryException
- The query is invalid
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createSQLRelationLoader
SQLRelationLoader createSQLRelationLoader(java.lang.String manyTable, java.lang.String[] idSQL, int[] idType, TypeConvertor[] idTo, TypeConvertor[] idFrom, java.lang.String[] relatedIdSQL, int[] relatedIdType, TypeConvertor[] ridTo, TypeConvertor[] ridFrom)
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