TomEE and JPA DataSources
This short article shows the different places DataSources can be defined for web applications using JEE running in a TomEE server.
The situation
In order that your @PersistenceContext
knows against which database it should connect, you have a META-INF/persistence.xml
which defines a persistence-unit
which defines a jta-data-source
:
META-INF/persistence.xml<?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_2.xsd"
version="2.2">
<persistence-unit name="PersUnitName" transaction-type="JTA">
<jta-data-source>jdbc/mydatabase</jta-data-source>
</persistence-unit>
</persistence>
Finally the database connection must be put into JNDI under jdbc/mydatabase
or to be more precise under java:comp/env/openejb/Resource/<CONTEXT>/jdbc/mydatabase
.
Where DataSources can be defined
In JEE 6 or later DataSources can be defined in
- a <data-source> in $WEBAPP/WEB-INF/web.xml (or application.xml, application-client.xml, ejb-jar.xml)
- a
@DataSourceDefinition
in one of your Java classes
Tomcat adds DataSource definitions under some more locations [1]:
- as a <Resource> inside <GlobalNamingResources> in $TOMCAT/conf/server.xml
- as a <Resource> inside <Context> in $WEBAPP/META-INF/context.xml
- as a <Resource> inside <Context> in $TOMCAT/conf/Catalina/localhost/mypath.xml
- as a <Resource> inside <Context> in $TOMCAT/conf/server.xml
TomEE adds even more DataSource definition locations [2]:
- as a <Resource> inside $TOMEE/conf/tomee.xml
- as a <Resource> inside $WEBAPP/WEB-INF/resources.xml
- as a list of key=value entries in $TOMEE/conf/system.properties
- as a “-D” command-line option
The bad news
Defining the <Resource> at any location in a <Context> does add a DataSource object into JDNI, but it doesn’t work for your application - this bug is files under https://issues.apache.org/jira/browse/TOMEE-263
I came up with a (maybe too simple) solution.
DataSource definitions in some detail
As we have seen DataSources can be defined in various locations, unfortunately they have different formats.
Under META-INF/context.xml (or any other “context”) it looks like:
<?xml version="1.0" encoding="UTF-8"?>
<Context><Resource name="jdbc/mydatabase" auth="Container"
type="javax.sql.DataSource" username="root" password=""
driverClassName="com.mysql.cj.jdbc.Driver"
url="jdbc:mysql://localhost/myschema" /></Context>
While in WEB-INF/resources.xml
<?xml version="1.0" encoding="UTF-8"?>
<tomee>
<Resource id="jdbc/mydatabase" type="DataSource">
JdbcDriver = com.mysql.cj.jdbc.Driver
JdbcUrl = jdbc:mysql://localhost/myschema
UserName = root
</Resource>
</tomee>
So long story short, make sure you are using the right format at the right place.
Links:
[1] https://tomcat.apache.org/tomcat-9.0-doc/jndi-resources-howto.html
[2] http://tomee.apache.org/datasource-config.html