As EasyBPEL is based on EasyVIPER, an extended behavior is expected to be developed for each extended activity in EasyBPEL.
First we consider an extended behavior is available (see the specific how-to on EasyVIPER page).

The following figure shows this principle of EasyBPEL activity mapped into an EasyVIPER behaviour. For the Invoke activity defined in the BPEL specification, a corresponding Send behavior has been implemented in EasyVIPER. In a same way, any extended activity defined at EasyBPEL level corresponds to an extended behavior at EasyVIPER level.

An extended activity implementation must be composed of a JAVA interface extending the ExtendedActivity interface:

A JAVA class must implement this MyExtendedActivity interface:

You have to fill the constructor (at least with a super() method), the convertElementToModel(), validate() and generate() methods.
The validate method SHOULD be filled whereas the generate method MUST be filled. It consists basically in instantiating the extended behavior developed at EasyVIPER level. Here is an example of generate method:

Your extended activity is completed. You only needs to add it in dependency of your BPEL engine and to set or create an ExtendedActivityInitialization.xml file that can be found for instance in the src/main/jbi of the JBI component that embeds EasyBPEL.

You can see in definition a file is set, that must be present in the extended activity project and that contains configuration. This configuratioon file details what is the namespace of the extended activity, and for each activity of this namespace, the tag associated to the extended activity (in the taken example, there was only one extended activity).