Why should I use a BPEL engine?

I found this wonderful presentation:

http://www.ibm.com/developerworks/websphere/library/techarticles/0803_fasbinder2/0803_fasbinder2.html

basically, use OSB when you have to do this:

validation
protocol mediation
transformations
messages enrichment
simple service composition with no compensation
static ou dynamic routing
load balancing and fault tolerance
error handling
monitoring performance and SLA


use a BPEL Engine for:
complex long running processes
service composition with compensation and complex orchestration