How to add binding to Script task

[elygre]

We are considering embedding Activiti into an application, where we want to enable the use of the application-specific APIs in Activiti script tasks:

// This is a groovy task
// The object "applicationSpecificApi" is injected into the script binding by us, similar to the object "execution"
def approvedAmount = execution.getVariable("amount");
def approvedBy  = execution.getVariable("user_id");
applicationSpecificApi.authorizeSpending (approvedAmount, approvedBy);
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How do we add such a binding (a reference to either documentation or sample code should suffice)?

Thanks,
Eirik

[jbarrez]

You would have to check how the ScriptTask is implemented. Somewhere in classes below, the task or execution is simply injected in a hashmap of objects that are available.

[elygre]

For reference, in case other people have the same question. It looks like there are two mechanisms that are more or less accessible.

First, the engine configuration has a list of "ResolverFactory", as shown in the code below (from ProcessEngineConfigurationImpl). By setting your own ResolverFactories, you can inject your own resolver:

protected void initScriptingEngines() {
   if (resolverFactories==null) {
      resolverFactories = new ArrayList<ResolverFactory>();
      resolverFactories.add(new VariableScopeResolverFactory());
      resolverFactories.add(new BeansResolverFactory());
   }
   if (scriptingEngines==null) {
      scriptingEngines = new ScriptingEngines(new ScriptBindingsFactory(resolverFactories));
   }
}
Second, the "BeansResolverFactory" which is inserted by default in the code above, uses "Map<Object, Object> ProcessEngineConfigurationImpl.getBeans()" to look for beans to inject (presumably the same beans that are available in expressions), so you can just set beans to be injected here:

// While creating the engine
Map<Object, Object> beans = new HashMap<Object, Object>();
beans.put("myservice", new MyService());
((ProcessEngineConfigurationImpl)config).setBeans(beans);

// In a script task
myservice.callMyFunction()
We ended up with the second solution, for now; it looks easy enough to change later, if required.