The following code produces an extra node that is unconnected ...
digraph kafka {
node [shape=rect, style=filled, fillcolor=lightyellow, fontname=Verdana, fontsize=9, arrowsize=0.8 label="producer"];
producer1 producer2 producer3;
node [label=consumer];
consumer1 comsumer2 consumer3;
kafka [label="kafka cluster"];
edge [label=" topic ", fontsize="8"];
producer1 -> kafka; producer2 -> kafka; producer3 -> kafka;
edge [label=" msg "];
kafka -> consumer1; kafka -> consumer2; kafka -> consumer3;
}
The image I was trying to reproduce using GraphViz is the one at:
http://kafka.apache.org/images/producer_consumer.png
All I am adding to that image is some extra formatting and edge labels ... but I get an extra node with label "consumer" unconnected to the rest of the graph.