visio like adge aggregation in graphviz

Can graphviz do edge aggre开发者_StackOverflow中文版gation like visio ? meaning something like

      o
      |
-------------
|   |   |   |
o   o   o   o

and if not does any other java tool can ?

Our customers are used to this kind of layout and I cant find the way to do it using graphviz

Thanks, Guy

Graphviz uses the term "concentrate" to refer to that functionality. See this page of the Graphfiz Wiki for more info.