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As discussed previously, we could also create launch files to load more than one instance of the nodelet class. The following launch file, hello_ros.launch, will load two nodelets with the names Hello1 and Hello2:

<launch> 
<!-- Started nodelet manager --> 
 
  <node pkg="nodelet" type="nodelet" name="standalone_nodelet"  args="manager" output="screen"/> 
<!-- Starting first nodelet --> 
 
  <node pkg="nodelet" type="nodelet" name="Hello1" args="load nodelet_hello_ros/Hello standalone_nodelet" output="screen"> 
  </node>             
 
<!-- Starting second nodelet --> 
 
  <node pkg="nodelet" type="nodelet" name="Hello2" args="load nodelet_hello_ros/Hello standalone_nodelet" output="screen"> 
  </node>             
 
</launch> 

We can launch the nodelets with this launch file as follows:

$ roslaunch nodelet_hello_world hello_ros.launch

Using rqt_graph, we can view how the nodelets interconnect inside the ROS framework:

$rosrun rqt_gui rqt_gui

ROS computational network graph showing two instances of a nodelet