Fault Handling In One-Way BPEL Process?

Guys,

Here's what I'm trying to do: if a composite returns certain data, mark the calling BPEL process as recoverable.

In order to test, I have a simple composite:

1. External service FTP Get polls file system for files

2. FTP Get passes payload, via simple Mediator, to one-way BPEL process

3. BPEL process does an assign (just so it has done something that can be recovered)

4. BPEL process throws the bpelx:assertFailure (I am unable to throw a user-defined fault, see below)

5. bpelx:assertFailure should be caught by fault handling framework

I can not see a way of defining a fault message against the