both are valid options. In the case of using an mdb, you also have to configure a queue, deploy the mdb etc, write a actionhandler that puts the message in the queue. When using async nodes this is done for you. You have less control in the latter situation about priorities etc...
thanks for your answer !
seems a match "draw" between the two options....anyway in case I have already an EJB layer clustered, it could be a better choice to use the MDB apporoach , so I have already HA out of the box for this operation...?
Yes, if you want to have robustness you should use JMS instead of the internal asynchronous support, which works well for simple applications, but not for the high end.
uhmm... internal async support IS robust since it uses ejbtimers IF you use the jBPM EE version.