Hi yuval, Your design is very good. I have one question that what's the order of parent's PreActivity and children's PreActivity.Maybe we should run parent's PreActivity after children's PreActivity.The attached pdf is my understanding of your design. I have put the children's PreActivity before parent's.Please take a look at it. Thanks! Very good work! best wishes! chenzeng -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20160506/9e929f85/attachment.html> -------------- next part -------------- A non-text attachment was scrubbed... Name: aother understanding of new protect flow.pdf Type: application/pdf Size: 119787 bytes Desc: not available URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20160506/9e929f85/attachment.pdf>