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So we have discussed about workspace and the package.

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It is a very basic thing and I assume that you understand it deeply through any Wikipedia page of Ross

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or any course that you have taken.

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I'm not going into deep detail how that works.

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We are just going to create workspace and package in it.

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So let's write the commands and I want you to be very comfortable with these commands by practice and

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let's start.

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So we are currently in our home folder and I'm going to create a directory.

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Within argument minus V because we need a subdirectory as well.

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The workspace name is going to be part planning workspace and a subdirectory inside of this workspace

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is going to be source just for now.

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Then we will move into this workspace and the source.

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Packages are going to be created in this for sauce for you too.

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So let's create a package.

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I have written the command here.

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We have it across to package create.

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Then the name of the package will type by type dependencies are sealed by any standard messages.

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Let me added just this command is hard to memorize.

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So I have written it in your repository and it will be very easy for you and for me it's but so let's

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created in the source folder package has been created and let's say the workspace call you can build.

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I'm not going to create Simulink.

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We are just going to create a simple called can build that will copy all the files into the shareholders.

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So package has been created and workspace has been built.

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So far things are working fine if there is an error with the call confining.

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You can cancel the wiki page that I have opened here for you.

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Docs not rostered or do foxy tutorials and they are in depth about all of these things.

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What I am going to do is create.

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A note of publisher subscriber to Tester workspace and package.

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Okay, so let's open the folder that we just created.

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That was part planning workspace, but planning workspace and the source folder, the maze board.

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Let's add it into our voice code so our life becomes very easy as it also gives us the capability of

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file managing.

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Here we have baseboard resources and other stuff and I assume that you know all about this stuff through

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my previous course or through Ros Vicky you can understand them.

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They are very easy, by the way.

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Or if you are not compatible, you will get after this course at the end of this course.

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Now let's create a folder named as source folder or know its roster.

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So we have this.

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Ms. but we have to write all Python related scripts inside of it, so it works like a Python package.

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What I am interested in is creating a publisher and subscriber to get started with What is this publisher?

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Note I'm going to copy the code here and you can run the Gate Command as well to obtain the file, but

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I will write the command.

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Okay, let's create a new file.

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I think its name was Docker Dot by.

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Base the game on.

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Was it a talker?

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Yes, it's a publisher, so it would be a target.

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And the next file is going to be a subscriber.

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Where is the code?

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Here is it.

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I'm going.

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Do not perform the second option.

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And let's open up the terminal control P to bring in this command pilot terminal or sorry, we have

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to press control shift B to bring the action panic dominant.

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Um.

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Create a terminal.

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It is in the maze, Bart.

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We have to bring it into another named Mes.

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But name folder inside of this means to me is what?

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If we list it, you can see we have the talker by and by these two, four years, I am going to be stuck

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on the blue grid and it is going to download the file subscriber member function.

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I'm going to rename it to be less net.

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Okay.

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I think the spellings are wrong, but I don't get.

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We have two files, and what we need to do now is to build the package.

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What executables of Python does this package needs to create?

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That thing is going to be happening in the set of five.

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I'm doing it fast because I want you to get started with the maze.

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Solving this is just basics, but I am giving you a refresher for that and I'm going to just copy and

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paste the commands from the wiki so you can get a deeper understanding from this wiki, not this lecture.

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And this is the process of adding entry point into your python based package so your package can understand

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what executable files to show to the ROS system and produce name is going to be Docker.

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I'm going to add it to be Docker node.

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This is the name that we will use to call this executable.

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The name of our package is Baseboard Board.

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So here we have the Mays bought.

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Package name, publisher, member function and the file name which is Docker Anarchy.

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So I am going to copy and paste Docker.

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Docker, just docker, not the BI.

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So I'm going to copy and paste it again because we have a subscriber as well.

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I just need to confirm one thing.

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Okay.

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The name is going to be subscriber?

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No.

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And.

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The name of the file is Listener.

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The basic syntax is you give the name of the package, you give the name of the code containing file

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the script.

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And what function do we need to call when we run your main function?

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In both of these files, we have this main function which we are calling now in setup goodbye file.

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These names are actually the names we will be using to call these functions, to call these files.

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So everything is fine.

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Let's perform calls.

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So these files get copied into the shared food.

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Now let's run it across to run and the name of the files word listener dot by and they are not available.

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The reason that I wanted to bring you here was we have to source our package with this source install.

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In store develop.

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Uh.

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What was it installed?

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Set up.

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Bash.

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What is happening here?

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Let me show you.

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So we have our package here.

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Part planning workspace in which we have these folders automatically created.

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We created just the source folder.

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But to make this workspace available to all of the ROS installation in this system or a virtual environment,

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we need to source a file of this workspace and that is this setup dot bash file.

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So I am writing this command inside of this folder, which is what folder?

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Go inside of the install folder and source this file.

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Let's source it.

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It has been source.

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Okay.

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Now we need to run those nodes that we created for us to run.

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And the name of the package is the name of the package was RMS bought previously?

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If I would have written me as but it should not appear.

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And I give you an example of listener directly.

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First, we need to write the name of the package and then name of the nodes.

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I'm double pressing the tab button.

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It is providing me all of the available options.

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So subscriber node and let's run it.

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There will be no output for one reason there is no listener.

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So let's open up a new terminal.

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And then.

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Execute the same thing.

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Me?

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What I'm pressing, Gavin, is not completing.

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And the reason is, whenever you open up a new terminal, you need to source the workspace you want

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to access.

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I know it is dieting, but I have a solution for that and.

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I'll show you the solution after this video.

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Ross to run maze pressing tap, I press step to confirm that it is automatically picking up the names

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Maze Board and the name of the file was Docker dot by right.

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If I now press enter and see the output of the subscriber, you can see both of these things are communicating

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with each other that how do I know that?

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Let's confirm it.

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With the help of our cute graph, which is the last thing that gives us information about nodes communicating

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with each other.

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Okay, you just need to write it up.

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No, Ross, do it on all.

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Although you get so minimum publisher is publishing and subscriber is subscribing on the name of the

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topic is topic.

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Let's take a look on the code now.

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So we have these two things.

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If I try to enlarge it now, they are fine.

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If I delete the command and see it in one video.

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In one window.

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This is the docket the talker is publishing on this topic.

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And then messages are sent into the buffer.

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The data type, as this time period is 0.00.5, meaning every second two packets are sent.

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The data is of string data type and this is going to be stored in the data and then it is going to be

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published and printed on this dominant on which this talk is coming to the next site whenever we run

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the subscriber.

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In an object oriented way.

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It has created a subscriber.

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And whenever the subscriber on this specific topic obtains any information, it is going to be calling

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this function.

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Listener callback.

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The listener callback is just printing what it has received from.

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I heard the this string and message data.

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So it is giving information.

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This publisher is giving information.

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Hello, world two, two, two.

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And this subscriber is getting information.

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I heard.

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Hello World.

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So this was the basic publisher subscriber and our workspace and package is set.

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Now we need to move towards making of the report and I am assuming that you have basic understanding

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of ROS workflow.