http://www.mastertheboss.com/jboss-jbpm/jbpm6/introduction-to-jbpm-6

http://www.mastertheboss.com/jboss-jbpm/jbpm6/jbpm-6-web-application-example

https://access.redhat.com/videos/872003

Reference Book about SIP

SIP: Understanding the Session Initiation Protocol, Fourth Edition

A DEEP DIVE INTO THE SIP PUBLISH/ SBSCRIBE METHOD

https://andrewjprokop.wordpress.com/2015/03/17/a-deep-dive-into-the-sip-publish-method/

https://andrewjprokop.wordpress.com/2015/03/11/a-deep-dive-into-sip-subscriptions/