Re: [wsbpel] installing compensation handlers for faulted scopes

[David RR Webber - XML ebusiness <Gnosis_@compuserve.com>]

Arkin,

This sounds suspiciously like how BPSS handles this - see 
attached diagram for repair parts ordering - where steps, 
actions, and succeed / fail sets are linked as components.

Of course in the example these are simple transition binaries,
but I like the broader object model - instead of the procedural
iterative one because:

1) Its much easier for business users to understand as it models
     their visualization of the sequences and events and coupling

2) Things don't have to be sequential - they can happen in parallel

3) The 'smarts' are in the runtime engine - and the user is freed from
     the mechanics of writing procedural code.

This being said - the notion of using the BPSS model as a highlevel
design tool to orchestrate BPEL components that become 
'choices' business users can add to their processing is definately 
appealing.

Thoughts?

Thanks, DW
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Message text written by Assaf Arkin
>
So then you decide to look at some common cases and realize that the 
best practice is to always do recovery in the fault handler. This sounds 
like a constraint that prevents you from doing simple things, but in 
fact it doesn't. It lets you model complex cases including parallel work 
with understandable logic if you use it correctly. And the best practice 
becomes very easy to write and adhere to.

That doesn't mean you can't get anywhere should a failure ensue. Let's 
say that some activity is talking to a supplier and encounters a problem 
and all it can do in its fault handler is recover from that and 
complete. But it's outcome is not a successful one, and by putting it 
inside a loop you can repeat it and have it talk to a different supplier 
until you get the desired outcome. You can repeat that any number of 
times, if you have N suppliers you can talk to all of them until you get 
a successful outcome.
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OAG-Refrigerator-Repair-Part-Ordering.jpg