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Writing Gateway Launchers

Tips

There are some key features that are typical to most gateway launchers:

• Public Args: exposing variables to users who'd like to modify behaviour from their own launcher

• Firewalling: blocking anything coming into your robot

• Default Flips/Pulls: setting a few regular expression rules to define flips/pulls that you want activated by default (saves alot of service calling).

• Hub Whitelists/Blacklists: be selective about where your gateway interacts on the lan.

Example

The following is a launcher used by the rocon_app_manager and demonstrates all of the above features.

<launch>
  <arg name="gateway_name" default="gateway"/>
  <!-- Polling period for multimaster advertising/flipping -->
  <arg name="gateway_watch_loop_period" default="5"/>
  <!-- semi-colon separated hub names/regex patterns -->
  <arg name="hub_whitelist" default=""/>
  <node pkg="rocon_gateway" type="gateway.py" name="gateway">
    <rosparam command="load" file="$(find rocon_gateway)/param/default.yaml" />
    <rosparam command="load" file="$(find rocon_gateway)/param/default_blacklist.yaml" />
    <rosparam command="load" file="$(find rocon_app_manager)/param/app_manager_advertisements.yaml" />
    <rosparam command="load" file="$(find rocon_app_manager)/param/app_manager_flips.yaml" />
    <!-- The paired hub, if available -->
    <rosparam param="hub_uri">http://localhost:6380</rosparam>
    <param name="name" value="$(arg gateway_name)"/>
    <!-- Nothing comes in! -->
    <rosparam param="firewall">true</rosparam>
    <param name="watch_loop_period" value="$(arg gateway_watch_loop_period)"/>
    <param name="hub_whitelist" value="$(arg hub_whitelist)"/>
  </node>
</launch>