Hibernate ORM within WildFly

The WildFly application server includes Hibernate ORM as the default JPA provider out of the box.

This means that you don’t need to package Hibernate ORM with the applications you deploy on WildFly, instead the application server will automatically enable Hibernate support if it detects that your application is using JPA.

You can also benefit from these modules when not using JPA or JavaEE, to avoid including Hibernate ORM and all its dependencies into your deployment. This will require activating the module explicitly using a jboss-deployment-structure.xml file or a Manifest entry: see Class Loading in WildFly for some examples.

There may be times though where a newer version of Hibernate ORM is available than the one coming with a given WildFly release. For that case the Hibernate ORM project provides a ZIP file containing the required modules, so that each new version can also be included in WildFly. Such a module will not replace the existing Hibernate ORM module, but it will become an alternative option that your application can choose to use instead of the default version it includes.

Our goal is to provide a module ZIP file targeted at the WildFly version current at the time of the Hibernate release (e.g. WildFly 10 for Hibernate 5.1.x and 5.2.x).

Where to download the modules from

The module ZIP files can be downloaded from Maven Central, to facilitate automatic unpacking during your build.

Example 1. Maven identifier for the WildFly modules zip file

Once downloaded, extract the contents of the ZIP file into the modules directory of your WildFly installation.

Example 2. Example Maven build step to prepare WildFly with custom Hibernate ORM modules for integration tests

WildFly module identifiers: slots and conventions

Note that the Hibernate ORM modules coming with WildFly will remain untouched: you can switch between the original version and the new version from the ZIP file as needed as a matter of configuration. Different applications can use different versions.

The application server identifies modules using a name and a slot. By default, the module org.hibernate:main will be used to provide JPA support for given deployments: main is the default slot and represents the copy of Hibernate ORM coming with WildFly itself.

By convention all modules included with WildFly use the "main" slot, while the modules released by the Hibernate project will use a slot name which matches the version, and also provide an alias to match its "major.minor" version.

Our suggestion is to depend on the module using the "major.minor" representation, as this simplifies rolling out bugfix releases (micro version updates) of Hibernate ORM without changing application configuration (micro versions are always expected to be backwards compatible and released as bugfix only).

For example if your application wants to use the latest version of Hibernate ORM version 5.2.x it should declare to use the module org.hibernate:5.2. You can of course decide to use the full version instead for more precise control, in case an application requires a very specific version.

Switch to a different Hibernate ORM slot

In order to use a different module other than the default org.hibernate:main specify the identifier of the module you wish to use via the jboss.as.jpa.providerModule property in the persistence.xml file of your application, as in the following example.

Example 3. Using an alternative module slot of Hibernate ORM
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
    version="2.1" >

    <persistence-unit name="examplePu">

        <!-- ... -->

            <property name="jboss.as.jpa.providerModule" value="org.hibernate:5.2"/>

        <!-- ... -->


Needless to say, this will affect the classpath of your application: if your single application declares multiple persistence units, they should all make a consistent choice!

This property is documented in the WildFly JPA Reference Guide; you might want to check it out as it lists several other useful properties.

Avoiding outdated Javassist versions from WildFly

Since Hibernate ORM version 5.2, it requires a more recent version of Javassist than the one provided by WildFly 10. Unfortunately the JPA subsystem of WildFly will expose its Javassist version to any JPA application even if you override the module using the above mentioned jboss.as.jpa.providerModule property.

To avoid this problem use a jboss-deployment-structure.xml to explicitly demand to not get the WildFly copy of javassist. This will allow Hibernate ORM to use the Javassist version provided by its own module, which will contain the recommended versions.

Example 4. WildFly configuration file to avoid the wrong Javassist version
<jboss-deployment-structure xmlns="urn:jboss:deployment-structure:1.1">
            <module name="org.javassist" />

This file needs to be included in your deployment, in the top level archive. The exact position depends on the deployment kind: for example when deploying a WAR file, include it in WEB-INF; other common deployment archives will expect this resource to be found in META-INF.

See Class Loading in WildFly for more details about using a custom jboss-deployment-structure.xml.

Limitations of using the custom WildFly modules

When using these modules you’re going to give up on some of the integration which the application server normally automates.

For example enabling an Infinispan 2nd level cache is straight forward when using the default Hibernate ORM module, as WildFly will automatically setup the dependency to the Infinispan and clustering components. When using these custom modules such integration will no longer work automatically: you can still enable all normally available features but these will require manual configuration, as if you were running Hibernate in a different container, or in no container.