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 (TODO link to easyviper how to)).

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