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Referencing entities from other jars in EAR

I'm trying to create a layered web proyect with an EAR. I divided the Entities from the DataAccess in order to only allow DataAccess to be called by BusinessLogic.
I'm actually getting this exception:
Object: co.edu.icesi.i2trading.entities.Statetype#21397ba0 is not a known entity type.
And I found here that I need to create a persistence.xml in the EAR, but I can't really understand how.
Sharing a persistence unit across components in a .ear file
I tried placing the XML file in the Configuration Files:
And referencing the jar with <jar-files> in the persistence.xml;
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 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 http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="I2TradingDataAccessPU" transaction-type="JTA">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<jta-data-source>jdbc/I2DataSource</jta-data-source>
<jar-file>../I2TradingEntities.jar</jar-file>
<jar-file>../../I2TradingEntities.jar</jar-file>
<shared-cache-mode>NONE</shared-cache-mode>
<properties>
<property name="eclipselink.target-server" value="None"/>
<!-- <property name="eclipselink.logging.level" value="ALL"/> -->
<property name="eclipselink.logging.level" value="WARNING"/>
</properties>
</persistence-unit>
</persistence>
With no success. Any idea why? I'm very new to Web Developing and this is getting to my nerves.
I'm also getting this WARNING in the persistence.xml's DESIGN tab:

I believe that the instruction jar-file interprets any path from the file that holds the persistence.xml... So, your configuration specifies that the Entities JAR are siblings of your EAR file.
The best (and easy) solution for your problem is to put the given persistence.xmlat the META-INF folder of your I2TradingEntities.jar and remove the <jar-file> instructions from it ... This will instruct the Application Server to create a PersistenceContext called "I2TradingDataAccessPU" and to detect any #Entity Class contained in that JAR.

Java EE jta hibernate.hbm2ddl.import_files does not work

I try to import sql file when web application runs. I placed import.sql into src/main/resources/import.sql. Then I modified my persistence.xml by adding import_files directive:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
version="2.1"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jsp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="spPU" transaction-type="JTA">
<description>SP Persistence Unit</description>
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<jta-data-source>java:jboss/datasources/SpDS</jta-data-source>
<properties>
<property name="hibernate.hbm2ddl.auto" value="create"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="false"/>
<property name="hibernate.hbm2ddl.import_files" value="import.sql"/>
</properties>
</persistence-unit>
</persistence>
But after redeploy or restart server nothing to uploads in database.
I use WildFly 8.1.0, Hibernate 4.3.5.Final, Database h2database 1.3.161.
I tried to remove blank lines from import.sql and change hibernate.hbm2ddl.auto to create-drop.
Any idea why import.sql does not load in database?

I had similar situation, please check if:
1) You can run your sql script manualy (No SQL errors are shown when error occurs during import)
2) Please make sure that all sql statements are single-lined, eg:
create table Table1{ column1, column2,etc.};
instead of
create table Table1{
col1 ..,
col2 ..,
}
I noticed these 2 issues when using import, hope this solves your problem too.
[UPDATE]
Thx to #vsapiha there is support for multiple lines sql:
<property name="hibernate.hbm2ddl.import_files_sql_extractor">org.hibernate.tool.hbm2ddl.M‌​ultipleLinesSqlCommandExtractor</property>

You don't need to specify the import files. Hibernate will look by default at WEB-INF/classes/import.sql, the place where it will be in your WAR if you place the file where you did. I always use WAR and never had to specify the location of it.
If you use JAR, the import goes in the root of the file, according to this link. (I never tried it though).

No Entity metadata found for the class

I'm back with the same problem ...
I'm trying to uses queries in my Cassandra DB with Kundera (Cassandra ORM), this queries work in an others project but when I try to do it in webapp (using tomcat 6.0), I got this error :
com.impetus.kundera.metadata.KunderaMetadataManager - No Entity metadata found for the class
=> JavaNullPointerException.
But when I leave the persistence.xml from my project I got an other error. (NoPersistence.xml found or something ... )
So, my project found Persistence.xml, but not my Entity class : fileCassandra.
You can see my persistence.xml :
<?xml version="1.0" encoding="UTF-8"?>
<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
http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<!-- 192.168.3.107 -->
<persistence-unit name="cassandra_pu">
<provider>com.impetus.kundera.KunderaPersistence</provider>
<class>net.***.common.db.***.FileCassandra</class>
<properties>
<property name="kundera.nodes" value="localhost"/>
<property name="kundera.port" value="9160"/>
<property name="kundera.keyspace" value="KunderaExamples"/>
<property name="kundera.dialect" value="cassandra"/>
<property name="kundera.client.lookup.class" value="com.impetus.client.cassandra.pelops.PelopsClientFactory" />
<property name="kundera.cache.provider.class" value="com.impetus.kundera.cache.ehcache.EhCacheProvider"/>
<!-- <property name="kundera.cache.config.resource" value="/ehcache-test.xml"/> -->
</properties>
</persistence-unit>
</persistence>
net..common.db..FileCassandra I must replace by * because it's name from my companie ;)
The same methods (include EntityManager) works in junit on other project, when I build my project in Tomcat, this error appears ...

This happens when you have multiple entries of the same class in your classpath.
The ideal place to have your entities is closest to the same class loader which loads kundera core and client(HBase, Cassandra etc.).
For example, if these kundera files are under WEB-INF/lib, you'd rather have your entities under the application where as if kundera files are on the applications lib folder, better bundle your entities in a jar and put them there (and remove the entities in your app).

Only issue which i can see is classes and persistence.xml location.
try to place persistence.xml within /WEB-INF/classes/META-INF/, Provided that your entity definitions are within classes folder!
-Vivek

DDL generation and general persistence.xml settings (OpenJPA)

Summary
I'm trying to run a Java web application JPA 2.0 example. The example application was written to run in Glassfish, using EclipseLink as JPA provider.
I would like to convert it to run in TomEE with OpenJPA as the JPA provider, but I can't any detailed tutorials for getting up and running with OpenJPA.
Problem
I'm having trouble converting persistence.xml to work with OpenJPA instead of EclipseLink. More specifically, the given persistence.xml doesn't specify:
Entity classes. Are these necessary?
The desired JPA provider. Will the container default to something?
The JDBC driver. How do I specify an "in-memory" DB (just for initial testing purposes)?
Also:
How are the DDL generation properties expressed in OpenJPA? I wasn't able to find them the OpenJPA User Guide.
Details
Below is the EclipseLink persistence.xml:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
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 http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="order" transaction-type="JTA">
<jta-data-source>jdbc/__default</jta-data-source>
<properties>
<property name="eclipselink.ddl-generation" value="drop-and-create-tables" />
<property name="eclipselink.ddl-generation.output-mode"
value="both" />
</properties>
</persistence-unit>
</persistence>
I have the following Entity classes:
order.entity.LineItem
order.entity.LineItemKey
order.entity.Order
order.entity.Part
order.entity.PartKey
order.entity.Vendor
order.entity.VendorPart
Question
Does anyone know what the equivalent persistence.xml would look like for OpenJPA?
Alternatively, if anyone could point me to an OpenJPA tutorial that covers these issues that would be just as good

If you add the openjpa.jdbc.SynchronizeMappings property as shown below OpenJPA will auto-create all your tables, all your primary keys and all foreign keys exactly to match your objects
<property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)"/>
Alternatively, you can use EclipseLink in TomEE by just adding the EclipseLink jars to <CATALINA_HOME>/lib/
refer here for Common PersistenceProvider properties

Foreign key constraints
The next line does not create foreign keys:
<property name="openjpa.jdbc.SynchronizeMappings"
value="buildSchema(ForeignKeys=true)"/>
Only creates schema and deletes content of a database.
But if you want create foreign keys, use the following lines:
<property name="openjpa.jdbc.SynchronizeMappings"
value="buildSchema(foreignKeys=true,schemaAction='dropDB,add')"/>
<property name="openjpa.jdbc.SchemaFactory"
value="native(foreignKeys=true)" />
<property name="openjpa.jdbc.MappingDefaults"
value="ForeignKeyDeleteAction=restrict, JoinForeignKeyDeleteAction=restrict"/>
See generated SQL
In another way, if you want to see the SQL output:
<property name="openjpa.Log"
value="DefaultLevel=TRACE,SQL=TRACE" />
NOTE: In order to see the generated output in the TomEE console, you need to change the log level in the file loggin.properties with openjpa.level = FINEST
See more in http://openjpa.apache.org/faq.html

Entities not mapped after moving them into external jar package

In my Java/Seam/JbossAS app, I decided to externalize my Model classes (hibernate entities) and moved them into another project. The project produces model.jar, which is then used by the main app. The model.jar dependency is resolved by Ivy.
Building the main app with Ant works without problems. Then I copy manually the model.jar into 'mainapp.ear/lib' directory. Afterwards I deploy the app and there are no problems (although I notice that there are is no log info about found mappings). But when I want to login, I get the exception:
javax.el.ELException: javax.ejb.EJBTransactionRolledbackException:
org.hibernate.hql.ast.QuerySyntaxException: AppUser is not
mapped [select u from AppUser u where u.userName = :usernamePar]
There were no code changes in the meantime, just externalizing some of the classes into a jar. Does this mean, that I need the source code of the Model classes when compiling the main app?

The EntityManagerFactory is built for scanning entities only from the jar that has a /META-INF/persistence.xml file into.
In order to scan other jars you have to use <jar-file>:
<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 http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="manager1" transaction-type="JTA">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<jta-data-source>java:/DefaultDS</jta-data-source>
<mapping-file>ormap.xml</mapping-file>
<jar-file>MyApp.jar</jar-file>
<class>org.acme.Employee</class>
<class>org.acme.Person</class>
<class>org.acme.Address</class>
<shared-cache-mode>ENABLE_SELECTOVE</shared-cache-mode>
<validation-mode>CALLBACK</validation-mode>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
</properties>
</persistence-unit>
</persistence>
See 2.2.1 Packaging in Hibernate doc.

Also check if your hibernate mappings are correctly placed wrt hibernate config file. Note that hibernate mapping resources or classes are relative to the location of hibernate.cfg.xml file.