[jboss-user] [JBoss Seam] - can't access non-Seam variables from jPDL decision condition
Hello,
After significant amount of troubleshooting, I have discovered that the
org.jboss.seam.jbpm.SeamVariableResolver is used when resolving variables in a expression
inside jBPM jPDL when the process is started inside of Seam.
This is fine and very useful in many cases, however, in my scenario, I am doing the
following:
- starting the process from Seam with a single BUSINESS_PROCESS scope String var
- invoking Seam components from embedded jPDL scripts, which set process context
variables (non-Seam), that are subsequently referenced in condition expressions
- the condition expression evaluation uses the SeamVariableResolver and, as a result does
not see the variable I exposed from my script, although other scripts do (apparently they
use some different variable resolution strategy)
Here is my jPDL snippet:
| <node name="establishInterpretationProcess">
| <transition to="decideOnInterpretation">
| <script>
| <expression>
| import org.jboss.seam.Component;
| import com.foo.ECGInterpretationProcessNameResolverService;
|
| System.out.println("ECG ID is '" + ecgId +
"'");
|
| lookup =
Component.getInstance(ECGInterpretationProcessNameResolverService.NAME, true);
|
| interpretationName =
lookup.determineInterpretationProcessName(ecgId);
|
| System.out.println("Interpretation name in
establishInterpretationProcess is '" + interpretationName + "'");
| </expression>
| <variable name="ecgId" mapped-name="ecgId"
access="read"/>
| <variable name="interpretationName"
mapped-name="interpretationName" access="read,write"/>
| </script>
| </transition>
| </node>
|
| <decision name="decideOnInterpretation">
| <transition name="interpret" to="doInterpretation"/>
| <transition name="dontInterpret"
to="assignForManualInterpretation">
| <condition>#{interpretationName == null}</condition>
| <script>System.out.println("interpretationName was
null!");</script>
| </transition>
| </decision>
|
The specific behaviour here is that the expression #{interpretationName == null} always
evaluates to null, so the associated transition is always taken, regardless of the value
of the interpretationName process context variable (as set in the script)
I tried to outject a value with BUSINESS_PROCESS scope from my component invoked in the
script, but this also was not visible by the expression.
My design goal is to keep the process and the components loosely coupled (the current bsh
notwithstanding :P ) such that either can potentially be reused, which is why I am
wanting to hold some minimal state in the process context.
Does anyone have any suggestions about how I might work around this? I have an idea how I
might modify the SeamVariableResolver to look in the jBPM contexts as well as its own
scopes, but this seems like a big hammer.
thanks,
shea.
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