WEBVTT 00:00.050 --> 00:05.510 Let's now see how to use the custom interface you have just created inside your own code. 00:05.660 --> 00:06.800 First with Python. 00:06.800 --> 00:09.530 So we have created a hardware status interface. 00:09.530 --> 00:14.600 I'm just going to create a node that contains a publisher, and we're going to call it hardware status 00:14.600 --> 00:15.230 publisher. 00:15.260 --> 00:16.970 Okay very simple node. 00:16.970 --> 00:22.040 So let's go in our workspace in the Python package. 00:22.040 --> 00:27.140 So I'm going to use the same Python package here and create a new node. 00:27.380 --> 00:34.580 And let's create hardware status publisher dot p y. 00:35.030 --> 00:38.510 And let's make it executable. 00:39.680 --> 00:44.870 Now I'm going to go back to VS code which was already open here. 00:45.170 --> 00:51.290 Let's go to the Python package and let's do what we've done previously. 00:51.290 --> 00:55.430 Let's take the template and let's add it here. 00:55.460 --> 00:58.850 Hardware status publisher dot p y. 00:59.150 --> 01:08.150 And let's name this hardware status Publisher node here and there. 01:08.180 --> 01:19.460 Let's remove those comments and let's also rename the node hardware status publisher. 01:19.490 --> 01:20.330 Okay. 01:20.750 --> 01:21.890 Let's save. 01:21.890 --> 01:23.000 And then. 01:23.120 --> 01:29.240 So the first thing we do when we create a publisher is also to import the interface. 01:29.240 --> 01:38.600 So the interface we've created here you see it's my robot interfaces MSG hardware status. 01:38.600 --> 01:53.840 So in the code we are going to do from my robot interfaces dot msg import hardware status okay. 01:53.870 --> 01:54.710 And I save. 01:54.710 --> 01:57.140 And as you can see well you might have this. 01:57.140 --> 02:03.320 Probably you will have this if you just had VSCode already open like me is that it's not recognized. 02:03.320 --> 02:07.190 So the package is found somehow, but the interface is not recognized. 02:07.220 --> 02:08.300 And why is that? 02:08.330 --> 02:15.980 Well, here you see, I have VS code that was already opened previously in a terminal that was sourced. 02:16.280 --> 02:23.510 But since then we have built the package in that terminal and we have created a new interface. 02:23.810 --> 02:26.780 But vs code in the environment it's working. 02:26.810 --> 02:29.660 Doesn't know about this interface yet. 02:29.690 --> 02:31.430 And so how to solve that issue. 02:31.460 --> 02:32.690 Well it's very simple. 02:32.690 --> 02:40.040 After you create the interface better to close VS code and then to go in a terminal where you've already 02:40.040 --> 02:40.430 sourced. 02:40.430 --> 02:46.130 For example, here you just open a new one or you go to that one in a terminal where you have sourced 02:46.160 --> 02:55.190 your workspace with all the new interfaces, and then you go back here and you open VS code and this 02:55.190 --> 02:55.760 time. 02:55.760 --> 02:57.680 So let's give it a few seconds. 02:58.940 --> 03:01.400 You see we have Ros extension initializing here. 03:01.400 --> 03:03.230 And this time you see now it's green. 03:03.230 --> 03:04.610 It is found. 03:04.640 --> 03:07.370 And so we can use it with the autocompletion and all that. 03:07.400 --> 03:07.670 Okay. 03:07.700 --> 03:13.780 So make sure that when you build an interface and if you want to use it, then you close VSCode and 03:13.780 --> 03:15.790 you just open a new terminal. 03:15.790 --> 03:21.940 You open VSCode again, or you source an existing terminal and you see you open VSCode in a sourced 03:21.940 --> 03:22.690 environment. 03:22.720 --> 03:23.620 Very important. 03:23.650 --> 03:24.160 Great. 03:24.160 --> 03:28.660 So we have imported we have successfully imported the interface that we have created. 03:28.690 --> 03:34.900 Now, as you can see, we are using my robot interfaces inside my Python package. 03:35.140 --> 03:42.460 So we are using another package, which means I'm going to go to my package dot XML for the Python package 03:42.460 --> 03:42.850 here. 03:42.850 --> 03:45.130 And I'm going to add a new depend tag. 03:45.190 --> 03:50.410 Depend my robot interfaces. 03:52.000 --> 03:52.480 All right. 03:52.480 --> 03:56.080 So then now we have three dependencies and that's it. 03:56.110 --> 03:56.710 Okay. 03:56.710 --> 03:57.340 That's it. 03:57.370 --> 04:01.150 You just import it add the dependency in the package dot XML. 04:01.150 --> 04:02.320 And that's basically it. 04:02.350 --> 04:05.110 It's just like any other interface we have used previously. 04:05.140 --> 04:05.320 Okay. 04:05.350 --> 04:08.680 There is nothing more special about the interfaces that you create. 04:08.680 --> 04:10.960 And then well let's see how to use it. 04:10.960 --> 04:16.840 So I'm going to create a very simple Publisher self, let's call it hardware. 04:16.840 --> 04:28.690 So h w status pub is equal to self create publisher with hardware status. 04:29.050 --> 04:30.430 That's the interface here. 04:31.330 --> 04:35.410 And then let's call it hardware status. 04:35.530 --> 04:39.040 And let's give it a queue size okay. 04:39.040 --> 04:49.120 And let's create a timer self timer self create timer with let's say one second. 04:49.120 --> 04:53.650 And then let's create a callback actually not a call. 04:53.680 --> 04:58.810 Let's call it publish hardware status. 05:01.900 --> 05:02.200 Okay. 05:02.200 --> 05:06.520 That's going to be the function we use to create a message and publish on the topic. 05:06.670 --> 05:10.870 And so to create a message we are simply going to use the hardware status. 05:10.870 --> 05:15.400 So hardware status we are going to use the class and create an object. 05:15.400 --> 05:16.120 That's it. 05:16.320 --> 05:23.850 And then we can do MSG, dot and you see we have all of the fields, for example MSG dot temperature 05:24.810 --> 05:34.530 and let's say 43.7 and then MSG dot amateurs ready and let's say true. 05:35.010 --> 05:37.470 So you see we use the data type for each field. 05:37.470 --> 05:47.220 And then MSG dot debug message is equal to let's say nothing special. 05:47.250 --> 05:47.610 All right. 05:47.610 --> 05:53.340 So you see we just fill the different fields of the message that we have created. 05:53.340 --> 06:02.760 And then after we create the message we publish it with the hardware status publisher Dot publish the 06:02.760 --> 06:03.420 message. 06:03.420 --> 06:08.970 And then I can put the callback here self dot publish hardware status. 06:09.420 --> 06:11.310 And let's finish with a log. 06:11.790 --> 06:12.960 Get logger. 06:15.360 --> 06:25.740 Info with How do it status publisher has been studied. 06:26.100 --> 06:28.020 Okay, so I went quite fast here. 06:28.020 --> 06:32.670 But this is a structure that we have done already several times in this course. 06:32.700 --> 06:33.900 It's always the same. 06:33.900 --> 06:38.040 We create a publisher, a timer, we create a message, we publish the message. 06:38.070 --> 06:42.450 The only difference here is that we use a custom interface, but the code is basically the same. 06:42.450 --> 06:45.240 So let's save and let's test it. 06:45.240 --> 06:49.620 So I'm going to create a new executable here in setup.py. 06:50.010 --> 06:56.490 Let's name it hardware status publisher is equal to. 06:56.520 --> 06:58.530 So the file name is hardware. 06:59.100 --> 07:10.230 Actually we need to put the package name Mypy pkg dot hardware status publisher. 07:10.230 --> 07:12.240 And still the main function. 07:12.270 --> 07:12.450 Okay. 07:12.450 --> 07:17.790 You see I use a slightly different name for the executable and the file name this time, which is completely 07:17.790 --> 07:18.420 fine. 07:18.810 --> 07:26.490 And let's go there again And let's go back here and let's build. 07:26.610 --> 07:35.100 Click on build with packages select and the Python package. 07:36.720 --> 07:38.640 And then let's choose the workspace. 07:38.640 --> 07:40.050 Let's just do it here. 07:40.080 --> 07:45.720 We can just do the source install setup bash from the workspace directly. 07:46.080 --> 07:56.400 And then let's do Ros to run my Pi PG with hardware status publisher okay it is publishing. 07:56.400 --> 08:01.980 And here for example, let's do a Ros two topic list. 08:03.060 --> 08:11.880 We see hardware status and then Ros two topic equal hardware status. 08:12.120 --> 08:14.730 And as you can see we have an error message. 08:14.730 --> 08:16.950 So that's why I kept those terminals like this. 08:16.950 --> 08:19.020 Why do we have an error message. 08:19.020 --> 08:26.660 It says the message type is invalid simply because well if you remember we have built the message here, 08:26.660 --> 08:29.960 and since then we haven't sourced that environment. 08:29.990 --> 08:31.340 Okay, so this one is sourced. 08:31.370 --> 08:32.420 This one is sourced. 08:32.420 --> 08:36.740 So the same command here should run in this terminal. 08:37.970 --> 08:38.330 Okay. 08:38.360 --> 08:45.830 You see we receive the messages but not in that one because we haven't sourced the environment. 08:45.860 --> 08:46.100 Okay. 08:46.130 --> 08:47.720 So this is very important. 08:47.750 --> 08:53.210 And in this case, as you can see when we build a new interface and a new node, what I recommend really 08:53.210 --> 08:56.120 is just let's close everything. 08:57.110 --> 08:59.150 Let's reopen everything. 08:59.150 --> 09:08.180 So now everything is correctly sourced to run my Python pkg with hardware status publisher. 09:08.270 --> 09:18.020 And here for example, rose to topic equal with a hardware status. 09:19.490 --> 09:20.990 And this time is working. 09:20.990 --> 09:24.410 And we're just publishing the same thing every second. 09:24.440 --> 09:24.890 All right. 09:24.890 --> 09:29.660 So now you know how to use a custom message inside your own Python nodes.