## repository: https://code.ros.org/svn/ros-pkg
<<PackageHeader(nodelet_topic_tools)>>
<<TOC(4)>>

The `nodelet_topic_tools` package contains a MUX (`NodeletMUX`) and a DEMUX (`NodeletDEMUX`) nodelet. 

== MUX ==
`NodeletMUX` represent a mux nodelet for topics: it takes N (<=8) input topics, and publishes all of them on one output topic. One implementation of `NodeletMUX` can be found in [[pcl_ros]].

Usage example:
{{{#!xml block=launch
  <node pkg="nodelet" type="nodelet" name="pcl_manager" args="manager" output="screen" />
  <!-- MUX the data onto one topic -->
  <node pkg="nodelet" type="nodelet" name="data_mux" args="load pcl/NodeletMUX pcl_manager" output="screen">
    <rosparam>
      input_topics: [/passthrough/output, /normal_estimation/output]
    </rosparam>
  </node>
}}}

The above accepts data from `/passthrough/output` and `/normal_estimation/output`, and republishes it on `/data_mux/output`.

To compile the `NodeletMUX` nodelet in your library, add something like:
{{{#!cplusplus
typedef nodelet::NodeletMUX<sensor_msgs::PointCloud2, message_filters::Subscriber<sensor_msgs::PointCloud2> > NodeletMUX;
PLUGINLIB_DECLARE_CLASS (pcl, NodeletMUX, NodeletMUX, nodelet::Nodelet);
}}}

(replace `sensor_msgs::PointCloud2` with the message type of choice).


== DEMUX ==
`NodeletDEMUX` represent a demux nodelet for topics: it takes 1 input topic, and publishes on N (<=8) output topics. One implementation of `NodeletDEMUX` can be found in [[pcl_ros]].

Usage example:
{{{#!xml block=launch
  <node pkg="nodelet" type="nodelet" name="pcl_manager" args="manager" output="screen" />
  <!-- MUX the data onto one topic -->
  <node pkg="nodelet" type="nodelet" name="data_demux" args="load pcl/NodeletDEMUX pcl_manager" output="screen">
    <rosparam>
      output_topics: [/output1, /output2]
    </rosparam>
  </node>
}}}

The above accepts data from `/data_demux/input`, and republishes it on `/data_demux/output1` and `/data_demux/output2`.

To compile the `NodeletDEMUX` nodelet in your library, add something like:
{{{#!cplusplus
typedef nodelet::NodeletDEMUX<sensor_msgs::PointCloud2> NodeletDEMUX;
PLUGINLIB_DECLARE_CLASS (pcl, NodeletDEMUX, NodeletDEMUX, nodelet::Nodelet);
}}}

(replace `sensor_msgs::PointCloud2` with the message type of choice).

== Throttle ==

<<Version(Fuerte)>>

`NodeletThrottle` can throttle a topic in a nodelet to a specified rate. Note that this tool is in the `nodelet_topic_tools` namespace.

Usage example:
{{{#!xml block=launch
  <node pkg="nodelet" type="nodelet" name="nodelet_manager" args="manager" output="screen" />

  <node pkg="nodelet" type="nodelet" name="data_throttle" args="load my_pkg/NodeletThrottleImage nodelet_manager" output="screen">
    <remap from="topic_in"  to="camera/rgb/image_color"/>
    <remap from="topic_out" to="camera/rgb/image_color_throttle"/>
  </node>
}}}



To compile the `NodeletThrottle` nodelet in your library, add something like:
{{{#!cplusplus
#include <nodelet_topic_tools/nodelet_throttle.h>
#include <sensor_msgs/Image.h>
#include <pluginlib/class_list_macros.h>

typedef nodelet_topic_tools::NodeletThrottle<sensor_msgs::Image> NodeletThrottleImage;
PLUGINLIB_DECLARE_CLASS (my_pkg, NodeletThrottleImage, NodeletThrottleImage, nodelet::Nodelet);
}}}

(replace `sensor_msgs::Image` with the message type of choice).

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