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Hey now we will learn about the ros nodes So ros node is a modular identity that can have publisher

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 subscriber services and parameters for

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example if a person is a Node it can hear
it means it is subscribing and it can speed

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publishing let's learn more about the ros nodes
here is an illustration that explains the ros nodes

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and here you can see the nodes in the
circle there are three Nodes and they

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are communicating over the topic and there's a
service So currently do not know the service so you

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do not need to spend much time over to
it we will learn these things in the future

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ros2 node list here is the command
that will list all the active nodes

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and currently we have just one active node
we will open up another terminal and uh

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so here we have another node
let's see again the list

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teleop turtle and the turtlesim now we have two nodes let's monitor their connection using rqt_graph

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here we can select all and

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here are the node and there connection between them
we can select here nodes only and refresh and

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there you will see a simpler illustration do you
remember previously we used the remap keyword

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uh we use it to remap a topic now we will
remap a node so Ros 2 run turtlesim

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underscore node minus minus Ros minus args minus
remap and what we have to remap is the node

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node colon equal and we can
enter any name so let's enter

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turtlesimbot

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here we have another window a similar
one so let's see the list of ros nodes we have

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the three nodes right now this one new node turtlesim bot and we can also see the topic ros2

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topic list so we have three topics that are
related to the turtlesim we have two windows

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of turtlesim but we have three topics the topics
remain same because we just have changed the name

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of the Node let's see if we can operate both
turtlesim windows or with just one teleop

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yeah they're moving absolutely they are moving to
get a complete information about a node to learn

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about it's topic subscribers publisher and
the services action we can use a command ros2

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node info and the node name we will enter

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Turtlesim bot and it has displayed a list
of different things like subscriber publisher

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server and the client service clients
and uh actual server rqt underscore graph

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and here you can see the illustration of
the connection between the nodes and the topics

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so congratulations you have
learned to basics of ros nodes

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oh