expr.state

Use this property on a service to define state variables and other state variables that update them. Use it on a notify operation to trigger it on a particular state change.

<!-- NewCount updates Count -->
<service name="Expr"  
  provision="expr">  
  <prop name="expr.state"    
    Count="NewCount"/>
</service>

<!-- OldCount is the last 
known value of Count -->
<notify name="myNotify"  
  service="Sequencer"  
  clients="Expr"  
  fields="TRIGGER">  
  <prop name="expr.state"    
    Count="OldCount"/>  
  <prop name="expr.src"    
    content-type="text/x-erlang"><![CDATA[
Count > 5.  
  ]]></prop>
</notify>
Note: Variable names must start with a capital letter.