content/alternate-descriptors.mdtext

Title: Alternate Descriptors
As of OpenEJB 3.1.1, you have the ability to specify an alternate set of
deployment descriptors to use for a given environment.	This is focused
mostly on testing where it is often desirable to use a slightly different
configuration for a set of tests or even a specific test.

# When nothing else does the trick

Note that this approach was added as a catch-all for when one of the
simpler overriding techniques will not work.  For the common case of
needing to tweak your persistence.xml, see the [Configuring PersistenceUnits in Tests](configuring-persistenceunits-in-tests.html)
 page for a simpler approach.

For many reasons it is very inconvenient to have to maintain two sets of
descriptors, one for production and one for testing.  We aggressively add
features based on user feedback and questions.	If you are looking for a
way to solve a problem without duplicating entire descriptors, please let
us know.  You should never have to go the long way to do something simple.

<a name="AlternateDescriptors-openejb.altdd.prefix"></a>
# openejb.altdd.prefix

To use this functionality, just set the new "openejb.altdd.prefix" system
property or `InitialContext` property to something like "_test_", then any
descriptors in your META-INF/ directory that start with "_test._" will
override the regular descriptor.  So for example with an app like this:

 - META-INF/ejb-jar.xml
 - META-INF/*test*.ejb-jar.xml
 - META-INF/persistence.xml
 - META-INF/*test*.env-entry.properties

Just initialize your test case like so:


     Properties properties = new Properties();
     properties.setProperty(Context.INITIAL_CONTEXT_FACTORY,
          "org.apache.openejb.client.LocalInitialContextFactory");
     properties.setProperty("openejb.altdd.prefix", "test");
    
     InitialContext initialContext = new InitialContext(properties);


The logical result will be the prefixed file replacing the non-prefixed
file as the active descriptor:

 - META-INF/ejb-jar.xml -> *test*.ejb-jar.xml
 - META-INF/persistence.xml
 - META-INF/env-entry.properties -> *test*.env-entry.properties

This will work in any environment in which OpenEJB works (embedded,
standalone, tomcat, geronimo, etc.).

Note that there does *not* have to be an equivalent non-prefixed version of
the file.  In the example above, only a "test.env-entry.properties" file
exists and there is no equivalent plain "env-entry.properties" file.  This
prefixing works for any deployment descriptor in the META-INF/ directory or
WEB-INF/ directory.  The prefix does not have to be "test" and could be
anything you choose.  You can also have as many prefixed files as you need
and could even go as far as to have one prefix per individual test.

<a name="AlternateDescriptors-Morethanoneprefix"></a>
# More than one prefix

It is possible to have several prefixes, specified in order of preference,
so that it is possible to avoid duplicating descriptors that are used in
more than one "profile".  For example, the "foo" test case uses the same
"env-entries.properties" file as the "bar" test case, but both have their
own ejb-jar.xml files:

 - META-INF/ejb-jar.xml
 - META-INF/test.ejb-jar.xml
 - META-INF/footest.ejb-jar.xml
 - META-INF/bartest.ejb-jar.xml
 - META-INF/persistence.xml
 - META-INF/test.env-entry.properties

The "foo" test case could set the _openejb.altdd.prefix_ as follows:


     //...
     properties.setProperty("openejb.altdd.prefix", "footest, test");
    
     InitialContext initialContext = new InitialContext(properties);


Resulting the following logical view of the app:

 - META-INF/ejb-jar.xml -> *footest*.ejb-jar.xml
 - META-INF/persistence.xml
 - META-INF/env-entry.properties -> test.env-entry.properties

And the "bar" test case could set the  _openejb.altdd.prefix_ as follows:


     //...
     properties.setProperty("openejb.altdd.prefix", "footest, test");
    
     InitialContext initialContext = new InitialContext(properties);


Resulting the following logical view of the app:

 - META-INF/ejb-jar.xml -> *bartest*.ejb-jar.xml
 - META-INF/persistence.xml
 - META-INF/env-entry.properties -> test.env-entry.properties

In both scenarios the same env-entry.properties file
(test.env-entry.properties) is shared.

Note that there is a "test.ejb-jar.xml" file that is present, however in
both cases it is not used as the order of preference in the list is "left
to right" meaning most preferred first.