Re: [rules-users] [droolsflow] Code-based constraints for EventWait nodes - is this possible?
No, the constraint of an EventWait node (or the State node in Drools
5.1) can only be rule-based. The reason for this is that the rule
engine knows when to re-evaluates rules (based on the evailable input).
If you would use a code-based constraint, the engine would have no idea
when this code constraint might become true (if it was false at the
start). Only constant re-evaluation of the code constraint could
achieve this (which would be tremendously inefficient). Could you
explain why you would like to have this behaviour? Maybe there is an
alternative way to model this.
To change the value of a variable from inside the process (using an
action), simply use kcontext.setVariable(name, value). We do not
recommend manually changing the value of a process variable from outside
the engine. Again, could you explain why you would like to have this
functionality?
Kris
Quoting Alan.Gairey(a)tessella.com:
Can the constraint for an EventWait node in a flow be code-based
(rather
than rule-based)? The Eclipse plug-in (v 5.0.1) doesn't allow this to
be
specified, unlike say for a Split node, although the relevant XML can
of
course be edited.
Trying to load such a process flow results in a NullPointerException,
because the constraint is always interpreted as a rule.
Ideally what I'd like to do is have an EventWait node where the
constraint
tests the value of a process variable. This then leads me to another
question; is there a way of setting the value of a process variable
via
the Drools Flow API?
Thanks in advance for any help,
Alan
Tessella plc
26 The Quadrant, Abingdon Science Park, Abingdon, Oxfordshire, OX14
3YS
E: Alan.Gairey(a)tessella.com, T: +44 (0)1235 555511, F: +44 (0)1235
553301
www.tessella.com Registered in England No. 1466429
This message is commercial in confidence and may be privileged. It is
intended for the addressee(s) only. Access to this message by anyone
else
is unauthorized and strictly prohibited. If you have received this
message
in error, please inform the sender immediately. Please note that
messages
sent or received by the Tessella e-mail system may be monitored and
stored
in an information retrieval system.
Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm