The article directories

    • (1) background
    • (2) the premise
    • (3) task
      • Ⅰ preparation
      • ⅱ ros2 service Command
        • ros2 service list
        • Ros2 SRV show eloquent service type
          • Eloquent version
        • Ros2 service find (Dashing not supported)
        • Ros2 interface show (Dashing not supported)
        • ros2 service call
    • (4) summarize

(1) background

Services are also a means of communication, req/ RESPone is a trigger, and topic is a subscription

(2) the premise

  • Install ros2
  • Configure the environment
  • Put the turtle

(3) task

Ⅰ preparation

Start the turtle command:

ros2 run turtlesim turtlesim_node
ros2 run turtlesim turtle_teleop_key
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ⅱ ros2 service Command

ros2 service list

Lists the service command prompt

usage: ros2 service list [-h] [--spin-time SPIN_TIME] [-t] [-c]

Output a list of available services

optional arguments:
  -h, --help            show this help message and exit
  --spin-time SPIN_TIME
                        Spin time in seconds to wait for discovery (only
                        applies when not using an already running daemon)
  -t, --show-types      Additionally show the service type
  -c, --count-services  Only display the number of services discovered
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You can see it through commands and RQT

Ros2 SRV show eloquent service type

Is to look at some of the ways that SRV messages,

  • Execute command lineros2 srv show turtlesim/srv/SetPen
  • RQT view
  • The file to view

Eloquent version

Ros2 service find (Dashing not supported)

Find a service by type, using the Eloquent version

ros2 service find <type_name>
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For example,

ros2 service find std_srvs/srv/Empty
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Ros2 interface show (Dashing not supported)

To view the service message information,Eloquent version

Command:ros2 interface show <type_name>.srv

Example:ros2 interface show turtlesim/srv/Spawn.srv

ros2 service call

Invoke service, command line mode

ros2 service call <service_name> <service_type> <arguments>
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We call /clear and /spawn

ros2 service call /clear std_srvs/srv/Empty
ros2 service call /spawn turtlesim/srv/Spawn "{x: 2, y: 2, theta: 0.2, name: 'bigggg'}"
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(4) summarize

If the communication is not continuous, it is better to use Services and actions