Note: This tutorial assumes that you have completed the previous tutorials: Rocon Launch, Launching a Gateway Hub.
(!) Please ask about problems and questions regarding this tutorial on answers.ros.org. Don't forget to include in your question the link to this page, the versions of your OS & ROS, and also add appropriate tags.

Command Line Tools

Description: Convenient tools for gateway interaction from the command line.

Keywords: rocon, multimaster, gateway

Tutorial Level: BEGINNER

Next Tutorial: Gateway Graph Rqt Plugin

Overview

To keep the workflow concise and clear, we are using rocon_launch to kickstart a multimaster environment using linux terminals running roscores on different ports.

Launch Hub and Gateways

The following starts three separate ros masters - hub, gateway system with tutorials and a gateway system with nothing added (to act as the remote gateway).

> rocon_launch rocon_gateway_tutorials gateway_tutorials.concert --screen

== Operations ==

=== Flipping ===

For ease of testing, [[rocon_gateway]] provides some tools to conveniently interact with the gateways.

Interactively flipping the chatter publisher from the first gateway to the second (make sure you are on ROS_MASTER_URI=http://localhost:11312 here)

{{{
> rosrun rocon_gateway flip
> Create or cancel a flip rule (f/c): f
Automatically selecting target gateway pirate_gateway2 (only one visible)
Select a connection to flip (name-type-node):
    0) /chatter-subscriber-/listener
    1) /babbler-publisher-/babbler
    2) /chatter-publisher-/talker
    3) /fibonacci/client-action_client-/fibonacci_client
    4) /add_two_ints-service-/add_two_ints_server
    5) /fibonacci/server-action_server-/fibonacci_server
Enter [0-5] or regex keyed by name [e.g. /cha.* or .*]: 2
Information
  Local Gateway: /gateway
  Operation    : flip
  Flip Rules   : pirate_gateway2-/chatter-publisher-/talker
Proceed? (y/n): y

You can see here that connections are flipped based on a 'name-type-node' triple. Also note regex's are quite ok as well (this applies further to the actual service calls).

What this actually does is add a flip rule to a watchlist. When it finds a matching connection, it will immediately flip that connection to the specified gateway.

Cancelling a rule that has been added to the watchlist:

snorri@snorriwork64:/opt/multimaster$ rosrun rocon_gateway flip
> Create or cancel a flip rule (f/c): c
Automatically selecting /chatter (only one flip rule in the watchlist)
Information
  Local Gateway: /gateway
  Operation    : cancel
  Flip Rules   : pirate_gateway2-/chatter-publisher-/talker
Proceed? (y/n): y

The second method for gateway interactions is a two-step method, advertise-pull. One gateway advertises some of its connections for public use and another gateway can freely pull these (flipping provides a mechanism for the gateway system who have the connections, while pulling provides control for the gateway accessing the services).

First, let's advertise the /chatter publisher from the first gateway (ROS_MASTER_URI=http://localhost:11312):

> rosrun rocon_gateway advertise 
> Advertise or cancel advertisements (a/c): a
Select a connection to advertise (name-type-node):
    0) /chatter-subscriber-/listener
    1) /babbler-publisher-/babbler
    2) /chatter-publisher-/talker
    3) /fibonacci/client-action_client-/fibonacci_client
    4) /add_two_ints-service-/add_two_ints_server
    5) /fibonacci/server-action_server-/fibonacci_server
Enter [0-5] or regex keyed by name [e.g. /cha.* or .*]: 2
Information
  Local Gateway: /gateway
  Operation    : advertise
  Advertise Rules   : /chatter-publisher-/talker
Proceed? (y/n): y

Then, pull /chatter from the second gateway (ROS_MASTER_URI=http://localhost:11313):

> rosrun rocon_gateway pull 
> Pull or unpull connections (p/u): p
Automatically selecting /chatter (only one visible)
Information
  Local Gateway: /gateway
  Operation    : pull
  Pull Rules   : pirate_gateway-/chatter-publisher-/talker
Proceed? (y/n): y
snorri@snorriwork64:/opt/multimaster$ rostopic list
/chatter
/rosout
/rosout_agg
/zeroconf/lost_connections
/zeroconf/new_connections
snorri@snorriwork64:/opt/multimaster$ rostopic info /chatter
Type: std_msgs/String

Publishers: 
 * /talker_snorriwork64_24493_2191842069361869173 (http://192.168.10.123:58213/)

Subscribers: None

The functionality provided by these script are also accessible via the 'advertise', 'advertise_all', 'pull' and 'pull_all' services maintained by the gateway (with even more fine-grained control).

Introspection

Once you've flipped/advertised/pulled some services, you can use the following scripts to introspect on the gateway network.

Introspecting the local gateway (from the first gateway at ROS_MASTER_URI=http://localhost:11312):

> rosrun rocon_gateway gateway_info
Found a local gateway at /gateway
Gateway
  Namespace   : /gateway
  Name        : pirate_gateway
  Ip/Hostname : 192.168.10.123
  Connected   : True
  On Hub      : Pirate Hub
  Firewall    : False
  Public Watchlist
       : /chatter-publisher-/talker
  Public Interface
       : /chatter-publisher-/talker
  Flip Watchlist
       : pirate_gateway2-/babbler-publisher-/babbler
  Flipped Connections
       : pirate_gateway2-/babbler-publisher-/babbler
  Flipped in Connections
       : -
  Pull Watchlist
       : -
  Pulled Connections
       : -

Inspecting the remote gateways (in this case from the second gateway at ROS_MASTER_URI=http://localhost:11313):

> rosrun rocon_gateway remote_gateway_info 
Found a local gateway at /gateway
Local Gateway                                                                                                                           
  Namespace: /gateway                                                                                                                   
  Ip/Hostname: 192.168.10.123                                                                                                           
Remote Gateway                                                                                                                          
  Name       : pirate_gateway                                                                                                           
  Ip/Hostname: 192.168.10.123                                                                                                           
  Firewall   : False                                                                                                                    
  Public Interface                                                                                                                      
          : /chatter-publisher-/talker
  Flipped Interface
          : pirate_gateway2-publisher-/babbler-/babbler
  Pulled Interface
          : -

Using the Ros Services Directly

The functionality provided by these scripts are also accessible via the 'flip', 'flip_all', 'advertise', 'advertise_all' services maintained by the gateway. Using the services directly provides even finer grained control - regex based patterns for the gateway, name and node in a remote rule, the ability to provide a rule for a connection which doesn't exist yet, amongst others.

Wiki: rocon_gateway_tutorials/Tutorials/hydro/Command Line Tools (last edited 2013-04-22 02:44:47 by DanielStonier)