If "actionstate A" will call "actionstate A1",and "actionstate A1" will call "actionstate A11",then there is an "actionstate B" after "actionstate A"...
Can the activity diagram express these interaction?
A sad truth,there isn't sequence diagram in ArgoUML.If the activity diagram can't express the interaction between Objects,I will use collaboration diagram to express these model in my design phase of Filesharing module.