Overriding a provided API with an alternative version

In the following example, an application called Scholar needs to use classes that it provides (or that are provided in a library that it uses), rather than using the copies of the classes that are available in the Liberty profile.

• When the classes are packaged within the application, override the default parentFirst delegation behavior with a classloader element in the server.xml configuration file or a file that it includes:

  <application id="" name="Scholar" type="ear" location="scholar.ear">
    <classloader delegation="parentLast" />
  </application>

  This tells the application class loader to look at the Liberty profile classes only after looking in the application and its associated libraries for a class.
• When the classes are packaged in a shared library, add the delegation attribute to the classloader element that configures the use of the shared library as follows:

  <application id="" name="Scholar" type="ear" location="scholar.ear">
    <classloader delegation="parentLast" commonLibraryRef="mySharedLib"/>
  </application>
  
  <library id="mySharedLib">
    <fileset dir="${server.config.dir}/myLib" includes="*.jar" />
  </library>

You can also use the privateLibraryRef attribute for private libraries in an application. See Sharing a library across multiple Java EE applications.