WEBVTT 00:00.080 --> 00:05.930 In this lesson, we will use the Ros2 command line tool to introspect the interfaces that we have built 00:05.930 --> 00:11.210 and well, in fact, you've already seen the most important command line tools you can use here. 00:11.210 --> 00:15.890 I will make a global reminder, so maybe you can understand things that you might have missed. 00:15.890 --> 00:17.810 And there's going to be a few more tips. 00:17.810 --> 00:24.410 So the first very important thing is to make sure that all terminals are sourced, because maybe you 00:24.410 --> 00:29.270 have built an interface or a node somewhere, and you are still using a terminal that you have sourced 00:29.270 --> 00:31.550 previously, but not after building. 00:31.790 --> 00:39.020 And so the best thing we can do sometimes is just close all the terminals and then just open new ones, 00:39.650 --> 00:46.400 okay, because everything is sourced from the bashrc, we know that now we have all the terminals correctly 00:46.400 --> 00:46.970 sourced. 00:46.970 --> 00:48.500 Then to see an interface. 00:48.500 --> 00:50.270 We have already used that several times. 00:50.270 --> 01:00.530 Ros2 interface show for example using an existing package that was already installed in example interfaces, 01:01.160 --> 01:06.570 um, msg and let's say int 64. 01:07.140 --> 01:07.410 Okay. 01:07.440 --> 01:08.940 We can see the interface. 01:08.940 --> 01:11.220 We can also do Ros2 interface. 01:11.550 --> 01:14.910 Show my robot interfaces. 01:15.060 --> 01:18.120 SV compute rectangle area. 01:18.120 --> 01:25.530 So you see to show the interfaces from the global Ros2 installation or from our workspace is exactly 01:25.530 --> 01:26.130 the same. 01:26.160 --> 01:29.250 Okay, we are going to treat the interfaces the same way. 01:29.280 --> 01:34.320 Now there is another command you can use with Ros2 interface it's list. 01:34.320 --> 01:41.490 And that's going to list all of the interfaces that are installed and sourced in that environment. 01:41.550 --> 01:43.740 And that's going to be a lot. 01:43.890 --> 01:44.400 Okay. 01:44.430 --> 01:48.660 You can see there are quite a few interfaces actually. 01:48.660 --> 01:49.680 It's quite a lot. 01:49.830 --> 01:50.490 Okay. 01:50.610 --> 01:55.800 And you can see packages like for example geometry messages example interfaces. 01:55.830 --> 01:56.070 Okay. 01:56.100 --> 01:59.040 So you see a lot of things that we've used already. 01:59.040 --> 02:01.410 So there you have all the interfaces. 02:01.440 --> 02:05.250 Then for example let's do clear. 02:05.280 --> 02:12.610 If you want to see the interfaces for one package you can do Ros2 interface and then package. 02:13.120 --> 02:16.900 And then for example, my robot interfaces. 02:16.900 --> 02:19.360 You see the auto completion should work here. 02:20.260 --> 02:23.410 And we have all the interfaces for that package. 02:23.410 --> 02:24.880 So we have created two. 02:24.910 --> 02:30.250 Now let's do this command again for sensor messages. 02:30.250 --> 02:33.010 You see that package that we have seen before. 02:33.040 --> 02:36.010 This package is installed already for you. 02:37.120 --> 02:42.310 And we can find all of the messages in the sensor messages package. 02:43.030 --> 02:51.700 And then for each message you can do a Ros2 interface show if you want to see, for example, that one 02:51.700 --> 02:52.990 magnetic field. 02:53.380 --> 02:56.230 Okay, you can see this one is really quite complex. 02:56.230 --> 03:02.830 But what you can see, you can use Ros2 interface list, Ros2 interface package and Ros2 interface show 03:02.830 --> 03:06.730 to discover the different interfaces that you have installed. 03:06.730 --> 03:15.540 Now, if you have a running node like for example, the let's do hardware status publisher. 03:15.570 --> 03:21.390 If you have a running node, there are a few ways you can find the different topics and services and 03:21.390 --> 03:23.970 see what interface you need to use. 03:24.000 --> 03:27.360 Okay, so we've already seen that with Ros2 node. 03:27.390 --> 03:35.040 So you can find the node list and then rose to node info with that node. 03:35.220 --> 03:41.490 We can find already you see we have a publisher here with the name and we can already see the interface. 03:41.490 --> 03:43.500 So that's one way to find it. 03:43.500 --> 03:53.550 Then we can also do Ros2 topic list and then ros2 topic info with that topic name. 03:53.610 --> 03:56.250 And we also find the same information. 03:56.280 --> 03:56.640 Okay. 03:56.640 --> 04:00.810 So there are several ways to get to the same conclusion from the command line. 04:00.840 --> 04:10.980 Now let's stop that and let's start the add to int server that we've created in the section on services. 04:10.980 --> 04:12.930 So this time we have a service. 04:13.950 --> 04:20.770 Let's do a Ros two node list and then rust two node info. 04:22.330 --> 04:27.850 And you can see in the service list that's here. 04:27.880 --> 04:33.490 Service servers we have our service name and the interface. 04:34.150 --> 04:34.450 Right. 04:34.480 --> 04:37.900 And you can also do roles to service list. 04:39.340 --> 04:46.150 And then you have roles to service type with the name of the service. 04:46.240 --> 04:48.550 And we find the type again. 04:48.580 --> 04:49.000 All right. 04:49.000 --> 04:53.800 So it's quite easy to find the interface for existing topics and services. 04:53.800 --> 05:00.550 And to conclude here it's important to make the difference between the communication layer and the actual 05:00.550 --> 05:02.170 content of the communication. 05:02.200 --> 05:02.530 Okay. 05:02.560 --> 05:06.880 So the service for example the service here name and the topics. 05:06.880 --> 05:09.190 Those are the communication layers. 05:09.190 --> 05:13.570 And they are transporting some messages some interfaces. 05:13.570 --> 05:20.290 So the interface is the actual content that you send over the topic or over the service.