var a = $("#node_2 .frame");
    var b = $("#node_1 .frame");
    var posA = $("#node_2").position();
    var posB = $("#node_1").position();
    var xA = posA.left + (a.width()+20)/2;
    var yA = posA.top + (a.height()+20)/2;
    var xB = posB.left + (b.width()+20)/2;
    var yB = posB.top + (b.height()+20)/2;
    var dy = yB-yA;
    var dx = xB-xA;
    var rad = Math.atan2(dy,dx);
    l = $("#line");
    l.width(Math.sqrt(dy*dy+dx*dx));
    l.css('top', yA+((yB-yA)/2));
    l.css('left', xA+((xB-xA)/2)-(l.width()/2));
    l.css('-moz-transform', "rotate("+rad+"rad)");