[RSD] [ebxml-bp] Decision vs Fork

["Jean-Jacques Dubray" <jeanjadu@Attachmate.com>]

Discussion|oasis.ebbp;
Topic|Control Flow;
Point|Fork vs Decision;
JJD@
||Hi:  (This is a comment)
	
||I wanted to add from our discussion yesterday that a:
a) a fork means that several path are possible but we don't when and
which paths will be active
b) an XOR fork means that as soon as one of these path are active, all
the others become disabled. However, all were possible to start with
c) a decision differs from a fork in the sense that a decision selects
only one possible path, the other one is automatically disabled. An XOR
fork could be designed to operate like a decision, but a decision cannot
amount to an XOR fork.
	
ME@
If you have any of these with a transaction that does not exit to
another fork, join or decision does this effectively give you the
possibility to return to the same fork, decision etc
JJD@
A BTA must have exactly one outgoing transition. The transition can go
to an end state, go back to the fork, ... A fork simply means that
several BTAs can be able at the same time. Maybe "fork" is not the right
term since it is not technically an executed fork
@JJD
@ME	 
ME@
What does an OR fork mean?
An OR fork works in combination with the timeout. This is the only way
to end an OR fork unless all paths were completed. An OR fork is
typically used to manage CancelPO and ChangePO, all can happen any
number of time, 

ProcessPO
    \
________________ (or fork, TO=2 days)
\     \ /     \
\   Change  Cancel
\              \
[timeout]      EndState
\
________________
     \ 
     \
@ME	 
ME@
How does the isConcurrent affect these constructs?
JJD@
isConcurrent is limiting the ability to execute multiple BTA of the same
BT across collaboration instances (with the same party), or within the
same collaboration if multiple paths are open.

This is like a database, you do not allow for concurrency. You could say
that this is necessary for ProcessPO since you could be approving two
POs simultaneously, going over the spending limit of your customer, if
you did not know that these two POs are currently being processed.

@JJD
@ME	 
@JJD