I have been trying to learn how to connect to the embedded database Apache Derby that comes out of the box with glassfish4. What do I have to set in the src/META-INF/persistence.xml in my project? Is it somehow preconfigured? If not, how can I change its settings - through glassfish console?
Thanks in advance for your help.
You need to edit the persistence.xml to add the persistence-provider, the classes you want to manage, and some configuration for your database, in case you do not use JTA, in your IDE, and package it with the app. You can generally enter the following in the persistence.xml:
<persistence-unit name="call_it_as_you_want" transaction-type="RESOURCE_LOCAL">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>YourClass</class>
<properties>
<property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.ClientDriver" />
<property name="javax.persistence.jdbc.url" value="jdbc:derby://127.0.0.1:1527/yourDatabase;create=true" />
<property name="javax.persistence.jdbc.user" value="your_database_login" />
<property name="javax.persistence.jdbc.password" value="your_database_password" />
<property name="eclipselink.ddl-generation" value="drop-and-create-tables" />
</properties>
</persistence-unit>
Before that, check if derby runs on port 1527 - i think it should. If you are going to use JPA with EJBs you can use JTA configuration - in this case persistence.xml will only need to declare the pool you will create from the admin console of Glassfish.
Related
I have a couple of unit tests for an application's JPA layer. This JPA layer consists in JPA entities and a service providing the basic API required in order to persist the entities. The unit tets directly use the javax.persistence classes in order to handle the PersistenceManager. Then it tests the persistence API and I can see in the log the SQL statements to create tables and sequences, etc.
The relevant part of the persistence.xml file looks like:
<persistence-unit name="..." transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
...
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test"/>
<property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
<property name="hibernate.format_sql" value="false"/>
<property name="hibernate.show_sql" value="true"/>
</properties>
</persistence-unit>
...
I have downloaded H2 1.4.200, the Windows installer, and I installed it on Windows 10. Now using the H2 console I want to connect to the database and inspect the tables, sequences, etc. that were created automatically by Hibernate.
So, going to http://localhost:8082 I get the following:
But when I try to connect to my database, using the defined JDBC connection string, I get the following:
What am I doing wrong here ?
Many thanks in advance.
Nicolas
Finally, I've replaced H2 with Oracle.
I'm new to Hibernate and JPA in general.
I read a lot about this warning, but I still can't solve it.
The answers I read so far, said that it is necessary to have hibernate.cfg.xml in the project.
But I also read that:
If you are using JPA i.e. Hibernate EntityManager, you'll need the persistence.xml. So you generally don't need both as you use either Hibernate proprietary API or JPA.
(what is the purpose of two config files for Hibernate?)
Using persistence.xml I have this warning every time I use Hibernate.
This is my persistence.xml:
<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="integration"
transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<properties>
<property name="hibernate.dialect"
value="org.hibernate.dialect.MySQL5InnoDBDialect" />
<property name="hibernate.hbm2ddl.auto" value="update" />
<property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/db-name?autoReconnect=true"/>
<property name="hibernate.connection.username" value="root" />
<property name="hibernate.connection.password" value="root" />
<property name="hibernate.show_sql" value="false" />
<property name="hibernate.format_sql" value="true" />
<property name="hibernate.id.new_generator_mappings"
value="true" />
</properties>
</persistence-unit>
</persistence>
I can't figure out what I'm doing wrong.
Thanks in advances
It is just a warning stating that you are using a built_in connection pool which is not a suitable solution in the production environment, you should use the application server connection pool in the production environment. depending on your application server you can setup database connection inside your application server then configure hibernate to use that connection.
But if you want to solve this problem without configuring the application server you can see this.
I am new to JPA and use Hibernate as the JPA provider. I came to know that we need META-INF/persistence.xml configuration file.
I successfully created a simple Java program to persist data in DB using JPA.
All fine, doubts started when I looked into the persistence.xml file to understand it better.
Sample below:
<persistence-unit name="test-jpa" transaction-type="RESOURCE_LOCAL">
<properties>
<property name="hibernate.connection.driver_class" value="org.h2.Driver"/>
<property name="hibernate.connection.url" value="jdbc:h2:tcp://localhost/~/test"/>
<property name="hibernate.connection.username" value="sa" />
<property name="hibernate.connection.password" value="" />
<property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
<property name="hibernate.hbm2ddl.auto" value="create" />
<property name="hibernate.show_sql" value="true" />
</properties>
</persistence-unit>
The following is the Java code for reading the configuration:
EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("test-jpa");
The following are the doubts:
How do we know that Hibernate is the JPA provider? Is it inferred by seeing the property tags in the file?
In config file, there are many <property> tags, are they pre-defined which can appear in the file (for a given JPA provider) or can we randomly add any property? who reads those <property> tags?
A JPA provider would provide documentation that would tell you all of that. Doesn't yours? I'd be surprised.
You should either have a <provider> element in the persistence-unit to define which provider to use, or it would use the default for the environment that you are running in (in JavaSE you would need to have 1 and only one JPA provider in the CLASSPATH, in JavaEE the server would have its own default).
They are provider-specific. Any properties that are prefixed javax.persistence would be JPA STANDARD. The first 4 of those posted have javax.persistence variants that you should have used instead.
I'm using Wildfly with Hibernate and I will have two different projects accessing the same database. Each project has its own persistence.xml, but the datasources within the persistence.xml are the same. Currently I have one project with these datasources. This looks like this:
Project A:
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
<persistence-unit name="MyProjectPersistenceUnit" transaction-type="JTA">
<jta-data-source>java:jboss/datasources/myprojectDS</jta-data-source>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
<property name="hibernate.connection.useUnicode" value="true" />
<property name="hibernate.connection.characterEncoding" value="UTF-8" />
<property name="hibernate.connection.charSet" value="UTF-8" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.hbm2ddl.auto" value="validate" />
</properties>
</persistence-unit>
<persistence-unit name="MyProjectLoggingUnit" transaction-type="RESOURCE_LOCAL">
<non-jta-data-source>java:jboss/datasources/myprojectDS</non-jta-data-source>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
<property name="hibernate.connection.useUnicode" value="true" />
<property name="hibernate.connection.characterEncoding" value="UTF-8" />
<property name="hibernate.connection.charSet" value="UTF-8" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.hbm2ddl.auto" value="validate" />
</properties>
</persistence-unit>
</persistence>
The additional project's persistence.xml will look like this:
Project B:
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
<persistence-unit name="MyProjectLoggingUnit" transaction-type="JTA">
<jta-data-source>java:jboss/datasources/myprojectDS</jta-data-source>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
<property name="hibernate.connection.useUnicode" value="true" />
<property name="hibernate.connection.characterEncoding" value="UTF-8" />
<property name="hibernate.connection.charSet" value="UTF-8" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.hbm2ddl.auto" value="validate" />
</properties>
</persistence-unit>
</persistence>
The first project uses both JTA and RESOURCE_LOCAL transactions, so I can handle logging "manually". The second project uses JTA only since I only do logging operation there. Project A does CRUD operations, Project B does create operations only. Both projects run within the same Wildfly server. Is it possible that any problem, maybe with locking in database, transactions in Wildfly or whatever, could occur between project A and project B while accessing the same database with the same datasources from different projects as I do it?
I don't think so, but I'm afraid that some 'side effects' could occur I don't know yet.
There should not be any problem, as Datasource is managed by jboss, it will allocate connection as per your configuration, locking can occure if you are using same row for processing from different projects but let database take care of that.
And there are different entities involved for not creating any problem like tho TCP connection is same/ shared sessions and transactions are diffrent for operation, spring and hibernate both are mature and best what they do, unless you messed with configurations ;), your looks good.
I agree that in principal you should not worry! BUT, since we are not dealing with magic and there is always an explanation when something does not work, the only case you should worry is a potential business coupling between the 2 applications and of course ends up in the data base. What I am trying to say, is that if Application1 which uses the same DB with Application2, performs things on entities that eventually are expected to be visible/ update for the logic on the other application, then yes there might be a chance that you will face some technical deadlocks (eventually pretty fine for a DB) but could be a problem on the business code level.
It is a matter of design and higher coupling, which happens to result in a technical coupling on the DB. I am not sure if I describe it correct, as a high level concern :)
Im using JNDI for datasource defined in our application server(websphere) and it is configured to manage the db connection pool. I have a service deployed on that server which also defines db connection pooling as per the cofiguration below.
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">
<persistence-unit name="test">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.c3p0.min_size" value="1"/>
<property name="hibernate.c3p0.max_size" value="10"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.ejb.autodetection" value="hbm"/>
<property name="hibernate.use_sql_comments" value="true"/>
</properties>
</persistence-unit>
</persistence>
Now, my goal is to completely remove the db connection pooling management on the service and let the application service handle it. If I remove the two c3p0 entries, does that mean no db connection pooling is happening inside the service and all are managed by the application server?
Im new to this kind of thing, and inputs or reference is highly appreciated. Thanks
[UPDATE1]
From C3P0ConnectionProvider "Hibernate will use this by default if the hibernate.c3p0.* properties are set."
Based on the above xml, I already removed the default pooling. Now if I did not define any pooling provider on the service then I essentially removed the pooling on the service right? I feel this is a dumb question now but please confirm if this is correct. Thanks :)