Hi Diogo,
you can use the method
Collection<NodeInstance> getNodeInstances()
for example:
import org.jbpm.workflow.instance.WorkflowProcessInstance;
WorkflowProcessInstance processInstance=(WorkflowProcessInstance)ksession.startProcess("processId");
Collection<NodeInstance> currentNodeInstances=processInstance.getNodeInstances();
in collection currentNodeInstances you'll find all active nodes of processInstance!
I have answered your question?
Francesco