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Difference between revisions of "EclipseLink/UserGuide/JPA/Advanced JPA Development/Composite Persistence Units"

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''This page is under development''
 
''This page is under development''
 
 
= Composite Persistence Units=
 
= Composite Persistence Units=
  
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=== Passing EntityManagerFactory Properties to Composite Member Persistent Units ===
 
=== Passing EntityManagerFactory Properties to Composite Member Persistent Units ===
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'''''//REVIEWERS: The EntityManagerFactory information is still rough and still under development.//'''''
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While creating a composite persistent unit, <tt>EntityManagerFactory</tt> properties can be passed to composite member persistent units.   
 
While creating a composite persistent unit, <tt>EntityManagerFactory</tt> properties can be passed to composite member persistent units.   
 
* The value is a map, the key is a member persistence unit's name,
 
* The value is a map, the key is a member persistence unit's name,
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* Composite member Persistence Unit property could be either specified in its persistence.xml or passed to composite's <tt>createEntityManagerFactory</tt> through the <tt>eclipselink.composite.properties</tt> property.
 
* Composite member Persistence Unit property could be either specified in its persistence.xml or passed to composite's <tt>createEntityManagerFactory</tt> through the <tt>eclipselink.composite.properties</tt> property.
  
The following table shows how persistence unit properties that affect composite persistence units and composite member persistence units are handled. For complete <tt>PersistenceUnitProperties</tt> reference documentation, see [[http://www.eclipse.org/eclipselink/api/latest/org/eclipse/persistence/config/PersistenceUnitProperties.html |PersistenceUnitProperties]].'''''//REVIEWERS: Is that correct? Is this table needed for the user doc?//'''''
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The following table shows how persistence unit properties that affect composite persistence units and composite member persistence units are handled. For complete <tt>PersistenceUnitProperties</tt>> reference documentation, see [[http://www.eclipse.org/eclipselink/api/latest/org/eclipse/persistence/config/PersistenceUnitProperties.html |PersistenceUnitProperties]].'''''//REVIEWERS: Is that correct? Is this table needed for the user doc?//'''''
 
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** owns bidirectional relationship with a <tt>JoinTable</tt> with the target mapped in another composite member,
 
** owns bidirectional relationship with a <tt>JoinTable</tt> with the target mapped in another composite member,
 
** has any reference mapping that is privately owned with the target mapped in another composite member.
 
** has any reference mapping that is privately owned with the target mapped in another composite member.
* The inheritance hierarchy cannot be shared between different composite members.
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* If the target of a reference mapping is defined in a different composite member and <tt>JoinTable</tt> is used, the join table must belong to the target composite member. Such mappings must be unidirectional: the "invert" mapping cannot use <tt>mappedBy</tt>. That is because <tt>JoinTable</tt> must be defined in the same composite member with the target entity. Master mapping requires it to be in slave's member, slave mapping - in master's.You can work around this limitation by defining independent invert mapping with its own <tt>JoinTable</tt>. If you maintain both sides of the relationship, the two join tables will be in sync.
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The inheritance hierarchy cannot be shared between different composite members.
* A native query created without a result class must specify the target composite member persistence unit, for example:
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If the target of a reference mapping is defined in a different composite member and <tt>JoinTable</tt> is used, the join table must belong to the target composite member. Such mappings must be unidirectional: the "invert" mapping cannot use <tt>mappedBy</tt>. That is because <tt>JoinTable</tt> must be defined in the same composite member with the target entity. Master mapping requires it to be in slave's member, slave mapping - in master's.You can work around this limitation by defining independent invert mapping with its own <tt>JoinTable</tt>. If you maintain both sides of the relationship, the two join tables will be in sync.
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A native query created without a result class must specify the target composite member persistence unit, for example:
  
 
<source lang=java>
 
<source lang=java>
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</source>
 
</source>
  
No <tt>@CompositeMember</tt> annotation (or composite-member attribute) is required if <tt>CollectionTable</tt> is defined in the same composite member persistence unit as the source.
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No <tt>@CompositeMember</tt> annotation (or <tt>composite-member</tt> attribute) is required if <tt>CollectionTable</tt> is defined in the same composite member persistence unit as the source.

Revision as of 07:15, 4 July 2011

EclipseLink JPA


This page is under development

Composite Persistence Units

EL NewIn.png New in version 2.3.



Multiple persistence units with unique sets of entity types can be exposed as a single persistence context by using a composite persistence unit. A persistent unit that is part of a composite persistent unit is called a composite member persistent unit.

With composite persistence units:

  • Mapping relationships can be established among any of the entities in the composite.
  • The persistence context can access entities stored in different data sources.
  • Queries and transactions can be performed transparently across the complete set of entities.

For example, you could persist data from a single context into different data sources, as shown below:

em.persist(new A(..));
em.persist(new Z(..));
// Insert A into database1; insert Z into database2:
// the two databases can be from different vendors.
em.flush();


Configuring Composite Persistence Units

You can configure composite persistence units in persistence.xml or by passing properties to the EntityManagerFactory. In either case,

  • The transaction type should be specified in the composite persistence unit. Transaction types of composite members are ignored.
  • Data sources should be specified in composite member persistence units. Those specified in the composite are ignored.

See Persistence Unit Properties, below, for a list of the persistence unit properties available for configuring composite and composite member persistence units.

Configuring Composite Persistent Units in persistence.xml

A minimal configuration of a composite persistent unit in persistence.xml requires the following:

  • Use the eclipselink.composite-unit property to specify that it is a composite persistence unit. (Note: If this property is passed to the createEntityManagerFactory method or if it is set in system properties, it is ignored.)
  • Use the <jar-file> element to specify the jar files containing the composite member persistent units. The composite persistence unit will contain all the persistence units found in the jar files specified.

For example,

...
<jar-file>member1.jar</jar-file>
<jar-file>member2.jar</jar-file>
<properties>
    <property name="eclipselink.composite-unit" value="true"/>
</properties>
...

For other applicable properties, see Persistence Unit Properties, below.

Configuring Composite Member Persistent Units in persistence.xml

Use the eclipselink.composite-unit.member property to specify whether or not a persistent unit should be a member of a composite persistence unit:

  • true specifies that the persistent unit must be a member of a composite persistence unit.
  • false specifies that the persistent unit cannot be a member of a composite persistence unit (if, for example, it has dependencies on other persistence unit(s)).

For example,

...
<properties>
    <property name="eclipselink.composite-unit.member" value="true"/>
</properties>
...

Note: If eclipselink.composite-unit.member is passed to the createEntityManagerFactory method or if it is set in system properties, it is ignored.

//REVIEWERS: Design doc also says "If this property is set to true, the EntityManagerFactory can still be created, but it cannot be connected." I don't understand, as true is perfectly valid, no?//

For other applicable properties, see Persistence Unit Properties, below.

Passing EntityManagerFactory Properties to Composite Member Persistent Units

//REVIEWERS: The EntityManagerFactory information is still rough and still under development.//

While creating a composite persistent unit, EntityManagerFactory properties can be passed to composite member persistent units.

  • The value is a map, the key is a member persistence unit's name,
  • the value is a map of properties to be passed to this persistence unit.

//How express this code?//

"eclipselink.composite-unit.properties" -> (
   ("memberPu1" -> (   "javax.persistence.jdbc.user" -> "user1", 
                          "javax.persistence.jdbc.password" -> "password1",
                          "javax.persistence.jdbc.driver" -> "oracle.jdbc.OracleDriver",
                          "javax.persistence.jdbc.url" -> "jdbc:oracle:thin:@oracle_db_url:1521:db",
                    ) , 
   ("memberPu2" -> (   "javax.persistence.jdbc.user" -> "user2",
                          "javax.persistence.jdbc.password" -> "password2"
                          "javax.persistence.jdbc.driver" -> "com.mysql.jdbc.Driver",
                          "javax.persistence.jdbc.url" -> "jdbc:mysql://my_sql_db_url:3306/user2",
                    )


Examples

In the following example, the composite persistence unit compositePU specifies the transaction type and the server platform. It will contain all persistence units defined in member1.jar and member2.jar files.

<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence persistence_1_0.xsd" version="1.0">
    <persistence-unit name="compositePu" transaction-type="JTA">
        <provider>
            org.eclipse.persistence.jpa.PersistenceProvider
        </provider>
 
        <jar-file>member1.jar</jar-file>
        <jar-file>member2.jar</jar-file>
 
        <properties>
            <property name="eclipselink.composite-unit" value="true"/>
            <property name="eclipselink.target-server" value="WebLogic_10"/>
        </properties>
    </persistence-unit>
</persistence>

In the following example, the composite member persistence unit memberPu1 is defined in the member1.jar file. It can be used independently as well as inside composite persistence unit.

<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence persistence_1_0.xsd" version="1.0">
    <persistence-unit name="memberPu1" transaction-type="JTA">
        <provider>
            org.eclipse.persistence.jpa.PersistenceProvider
        </provider>
        <mapping-file>META-INF/advanced-entity-mappings1.xml</mapping-file>
        <jta-data-source>jdbc/OracleJtaDS</jta-data-source>
        <exclude-unlisted-classes>false</exclude-unlisted-classes>
        <properties>
            <property name="eclipselink.target-server" value="WebLogic_10"/>
            <property name="eclipselink.target-database" value="org.eclipse.persistence.platform.database.oracle.Oracle11Platform"/>
        </properties>
    </persistence-unit>
</persistence>

In the following example, the composite member persistence unit memberPu2 is defined in the member2.jar file. It has dependency on a class defined in member1.jar and cannotbe used independently.

<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence persistence_1_0.xsd" version="1.0">
    <persistence-unit name="memberPu2">
        <provider>
            org.eclipse.persistence.jpa.PersistenceProvider
        </provider>
        <mapping-file>META-INF/advanced-entity-mappings2.xml</mapping-file>
        <jta-data-source>jdbc/MySqlJtaDS</jta-data-source>
        <exclude-unlisted-classes>false</exclude-unlisted-classes>
        <properties>
            <property name="eclipselink.composite-unit.member" value="true"/>
            <property name="eclipselink.target-database" value="org.eclipse.persistence.platform.database.MySQLPlatform"/>
        </properties>
    </persistence-unit>
</persistence>

Deploying and Accessing a Composite Persistence Unit

All three jars – the composite and the two members– should be deployed on the same class loader. If they are deployed to an application server, the jars should be packed in an ear file. If they run standalone, the jars should be added to the class path.

A composite persistence unit can be accessed as with any other persistence unit.

  • It can be accessed using injection, for example:
@PersistenceUnit(unitName="compositePu")
EntityManagerFactory entityManagerFactory;
@PersistenceUnit(unitName="compositePu")
EntityManager entityManager;
EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("compositePu", properties);

Persistence Unit Properties

  • Composite Persistence Unit property can be specified either in its persistence.xml or passed to the createEntityManagerFactory method;
  • Composite member Persistence Unit property could be either specified in its persistence.xml or passed to composite's createEntityManagerFactory through the eclipselink.composite.properties property.

The following table shows how persistence unit properties that affect composite persistence units and composite member persistence units are handled. For complete PersistenceUnitProperties> reference documentation, see [|PersistenceUnitProperties].//REVIEWERS: Is that correct? Is this table needed for the user doc?//

PersistenceUnitProperties. property name composite pu composite member pu comment
COMPOSITE_UNIT eclipselink.composite-unit Processed advanced If specified by member then the member is substituted for its own members. //REVIEWERS: I think this means "If specified by a composite member persistence unit ..." But what does the rest of the sentence mean?//
COMPOSITE_UNIT_MEMBER eclipselink.composite-unit.member advanced Processed if specified by composite persistence unit, the composite must be member of another composite persistence unit. //REVIEWERS: This suggests that composite PUs can be composite member PUs of other composite PUs. Is that correct? Any limitations?//
COMPOSITE_PROPERTIES eclipselink.composite.properties Processed Ignored
TRANSACTION_TYPE javax.persistence.transactionType Processed Ignored
TARGET_SERVER eclipselink.target-server Processed Ignored
LOGGING_* eclipselink.logging.* Processed Ignored
PROFILER eclipselink.profiler Processed Ignored
COORDINATION_* eclipselink.cache.coordination.* Processed Ignored
SESSION_NAME eclipselink.session-name Processed advanced The member session name is used to read the session from sessions.xml, but the deployed session always has the same name as the member persistence unit (as it is defined in memberPuInfo.getPersistenceUnitName())
DEPLOY_ON_STARTUP eclipselink.deploy-on-startup Processed Ignored
VALIDATION_ONLY_PROPERTY eclipselink.validation-only Processed processed //REVIEWERS: bug 348815: WRONG BEHAVIOUR, should be processed by composite only, ignored by member persistence unit. Workaround for now: specify the property in the composite and in all its members.//
VALIDATION_* eclipselink.validation.* Processed Ignored
CLASSLOADER eclipselink.classloader Processed Ignored
THROW_EXCEPTIONS eclipselink.orm.throw.exceptions Processed Ignored
FLUSH_CLEAR_CACHE eclipselink.flush-clear.cache Processed Ignored
VALIDATE_EXISTENCE eclipselink.validate-existence Processed Ignored
JOIN_EXISTING_TRANSACTION eclipselink.transaction.join-existing Processed Ignored
PERSISTENCE_CONTEXT_* eclipselink.persistence-context.* Processed Ignored
ALLOW_ZERO_ID eclipselink.allow-zero-id Processed Ignored
SESSION_CUSTOMIZER eclipselink.session.customizer Processed Processed Customizers of member persistence units are processed before the composite persistence unit's customizer.
SESSIONS_XML eclipselink.sessions-xml Exception Processed Composite persitence units cannot be read from sessions.xml. Note that a non-composite persistence unit should be able to use a SessionBroker defined in sessions.xml.
JTA_DATASOURCE javax.persistence.jtaDataSource Ignored Processed
NON_JTA_DATASOURCE javax.persistence.nonJtaDataSource Ignored Processed
NATIVE_SQL eclipselink.jdbc.native-sql Ignored Processed
SQL_CAST eclipselink.jdbc.sql-cast Ignored Processed
JDBC_* javax.persistence.jdbc.* eclipselink.jdbc.* Ignored Processed
CONNECTION_POOL_* Ignored Processed
PARTITIONING.* eclipselink.partitioning.* Ignored Processed
EXCLUSIVE_CONNECTION_* eclipselink.jdbc.exclusive-connection.* Ignored Processed
CACHE.* eclipselink.cache.* Ignored Processed
TARGET_DATABASE eclipselink.target-database Ignored Processed
TABLE_CREATION_SUFFIX eclipselink.ddl-generation.table-creation-suffix Ignored Processed
EXCLUDE_ECLIPSELINK_ORM_FILE eclipselink.exclude-eclipselink-orm Ignored Processed
WEAVING eclipselink.weaving Processed Ignored A composite persistent unit switches weaving on and off for all its member persistent units.
WEAVING_* eclipselink.weaving.* Ignored Processed If the weaving is on, members use their own weaving properties.
DESCRIPTOR_CUSTOMIZER_* eclipselink.descriptor.customizer.* Ignored Processed //REVIEWERS: what about this from design doc: "TODO? Should we follow the same pattern as SessionCustomizer and process composite's DescriptorCustomizers after members' ones?"//
NATIVE_QUERY_UPPERCASE_COLUMNS eclipselink.jdbc.uppercase-columns Ignored Processed
UPPERCASE_COLUMN_NAMES eclipselink.jpa.uppercase-column-names Ignored Processed
BATCH_WRITING.* eclipselink.jdbc.batch-writing.* Ignored Processed
SESSION_EVENT_LISTENER_CLASS eclipselink.session-event-listener Processed Processed EventListener defined by a composite member won't receive evens risen by a UnitOfWork - only events risen by it's member. Also see bug 348766. EventListener specified by composite will receive all event (risen by either unit of work or members).
Exception_HANDLER_CLASS eclipselink.exception-handler Processed Processed First ExceptionHandler specified by member handles exception. If it is not specified or fails then composite's ExceptionHandler handles the original exception.
INCLUDE_DESCRIPTOR_QUERIES eclipselink.session.include.descriptor.queries Ignored Processed
ID_VALIDATION eclipselink.id-validation Ignored Processed
TEMPORAL_MUTABLE eclipselink.temporal.mutable Ignored Processed
ORM_SCHEMA_VALIDATION eclipselink.orm.validate.schema Ignored Processed
DDL_* Ignored Processed
PESSIMISTIC_LOCK_TIMEOUT javax.persistence.lock.timeout Ignored Processed
QUERY_TIMEOUT javax.persistence.query.timeout Ignored Processed
ORACLE_PROXY_TYPE eclipselink.oracle.proxy-type Ignored Processed

Entity Manager Properties

  • Composite Entity Manager property could be directly passed to createEntityManager method or setProperty method
  • Composite member property could be passed to the same methods through "eclipselink.composite.properties" property.
EntityManagerProperties. property name composite pu composite member pu comment
COMPOSITE_PROPERTIES eclipselink.composite.properties Processed Ignored
FLUSH_CLEAR_CACHE eclipselink.flush-clear.cache Processed Ignored
VALIDATE_EXISTENCE eclipselink.validate-existence Processed Ignored
JOIN_EXISTING_TRANSACTION eclipselink.transaction.join-existing Processed Ignored
PERSISTENCE_CONTEXT_* eclipselink.persistence-context.* Processed Ignored
ORDER_UPDATES eclipselink.order-updates Processed Ignored
EXCLUSIVE_CONNECTION_* eclipselink.jdbc.exclusive-connection.* Ignored Processed
JDBC_DRIVER javax.persistence.jdbc.driver Ignored Processed
JDBC_URL javax.persistence.jdbc.url Ignored Processed
JDBC_USER javax.persistence.jdbc.user Ignored Processed
JDBC_PASSWORD javax.persistence.jdbc.password Ignored Processed
JTA_DATASOURCE javax.persistence.jtaDataSource Ignored Processed
NON_JTA_DATASOURCE javax.persistence.nonJtaDataSource Ignored Processed
CONNECTION_POLICY eclipselink.jdbc.connection-policy Ignored Processed
ORACLE_PROXY_TYPE eclipselink.oracle.proxy-type Ignored Processed

Limitations

Joins across tables in different data sources are not supported. This limitation affects mapping, query execution, and optimizations. For example:

  • Entities mapped in different composite members cannot be joined in a query.
  • If deleting an entity causes deletion from a table that is mapped by another composite member, then a "delete all" query cannot be performed. Therefore a delete all cannot be used if an entity:
    • has ElementCollection mapped in another composite member,
    • owns bidirectional relationship with a JoinTable with the target mapped in another composite member,
    • has any reference mapping that is privately owned with the target mapped in another composite member.

The inheritance hierarchy cannot be shared between different composite members.

If the target of a reference mapping is defined in a different composite member and JoinTable is used, the join table must belong to the target composite member. Such mappings must be unidirectional: the "invert" mapping cannot use mappedBy. That is because JoinTable must be defined in the same composite member with the target entity. Master mapping requires it to be in slave's member, slave mapping - in master's.You can work around this limitation by defining independent invert mapping with its own JoinTable. If you maintain both sides of the relationship, the two join tables will be in sync.

A native query created without a result class must specify the target composite member persistence unit, for example:

em.createNativeQuery("SELECT F_NAME FROM MBR2_EMPLOYEE").setHint(QueryHints.COMPOSITE_UNIT_MEMBER, "composite-advanced-member_2").getResultList();

Extensions

You can specify ElementCollection with primitive type target values with CollectionTable defined in a different composite member persistence unit, using annotations or eclipselink-orm.xml as described below:

  • Annotations
@ElementCollection()
@CollectionTable(name = "MBR1_RESPONS", joinColumns=@JoinColumn(name="EMP_ID"))
@CompositeMember("composite-advanced-member_1")
@Column(name = "DESCRIPTION")
public Collection<String> getResponsibilities() {
    return responsibilities;
}
  • eclipselink-orm.xml
<element-collection name="responsibilities" composite-member="xml-composite-advanced-member_3">
    <column name="DESCRIPTION"/>
    <collection-table name="XML_MBR3_RESPONS">
        <join-column name="EMP_ID"/>
    </collection-table>
</element-collection>

No @CompositeMember annotation (or composite-member attribute) is required if CollectionTable is defined in the same composite member persistence unit as the source.