Changing Process variables

[maxip]

Hi,

my plan is that people can easily add variablse into a process and using them for decisions.

So i assign a variable:

<start-state name="start">
 <task name="start">
 <controller>
 <variable name="einkaufswert" access="read,write,required"></variable>
 </controller>

 </task>
 <transition name="system_ist_gestartet" to="Verkäufer fordert Ware an"></transition>
 </start-state>

i want to use them like this:

<decision name="Einkaufswert &lt; 5000 ?">
 <transition name="false" to="Auftrag ausführen">
 <condition expression="#contextInstance.variables['einkaufswert'] lt 5000"/>
 </transition>
 <transition name="true" to="Abteilungsleiter überprüft Auftrag">
 <condition expression="#contextInstance.variables['einkaufswert'] ge 5000"/>
 </transition>
 </decision>

And now:

How can i assign a value to this variable named einkaufswert ?

And which script language is uses for this and where can i find a manual or tutorial for this script language ?

thx a lot

cya maxip