WEBVTT 00:00.080 --> 00:05.390 Let's come back to the turtle sim package and experiment a little bit more with services. 00:05.390 --> 00:13.670 So let's run the turtle SIM node first rose to run turtle sim and turtle sim node. 00:14.480 --> 00:18.440 All right I'm going to put it here on the side. 00:18.440 --> 00:23.090 And here let's also run the Teleop turtle node. 00:23.090 --> 00:26.510 So Ros to run turtle SIM. 00:26.510 --> 00:29.210 And it was turtle. 00:30.410 --> 00:31.010 Turtle key. 00:31.040 --> 00:34.010 That's the executable name okay. 00:34.010 --> 00:36.140 Let's make the turtle move a bit. 00:36.920 --> 00:37.790 All right. 00:37.850 --> 00:38.870 That's it. 00:39.380 --> 00:43.970 Now here on this terminal let's see what services we have. 00:43.970 --> 00:48.080 So let's do directly Ros2 service list. 00:49.100 --> 00:51.620 And you can see we have a bunch of services. 00:51.620 --> 00:54.620 So we can find first you see Top Turtle. 00:54.620 --> 01:01.360 We can find those seven services that are linked to most of the parameters for that node. 01:01.450 --> 01:06.400 Then we have the total SIM with those seven parameters for that node. 01:06.400 --> 01:12.520 And so if we remove those you see that we have four services here. 01:12.520 --> 01:14.890 And then we have three more here. 01:14.890 --> 01:18.760 So we have seven services specific to this application. 01:18.790 --> 01:19.060 All right. 01:19.060 --> 01:20.200 So it's already quite a lot. 01:20.230 --> 01:22.030 Now let's try to use one. 01:22.030 --> 01:23.950 Let's try to use the first one here. 01:23.950 --> 01:24.550 Clear. 01:24.550 --> 01:26.290 What is this service. 01:26.290 --> 01:31.090 This service is going to clear the trace that the turtle leaves here. 01:31.090 --> 01:34.750 So let's do ros2 service. 01:34.780 --> 01:35.740 What can we do. 01:35.770 --> 01:40.930 We already have the name we can do type slash clear okay. 01:40.960 --> 01:42.580 We can use the auto completion. 01:42.760 --> 01:47.890 And you see that we have an interface STD service. 01:47.890 --> 01:49.660 So that's standard services. 01:49.660 --> 01:52.270 And then slash SRV and empty. 01:52.360 --> 01:54.880 What do we have inside this interface. 01:54.880 --> 01:58.660 So we can do Ros2 interface show. 01:58.660 --> 02:05.050 And and you can see it's empty as its name suggests, it's empty. 02:05.050 --> 02:06.910 So so we don't have any request. 02:06.940 --> 02:10.120 Actually, it's not that we don't have any request and response. 02:10.120 --> 02:16.540 We have a request and we have a response, but they just contain nothing, which is perfectly valid. 02:16.540 --> 02:18.250 And you see we have three dashes. 02:18.250 --> 02:23.980 So that is the actual minimum thing you can do to write an interface with three dashes. 02:23.980 --> 02:28.000 Here you just say that the request is empty and the response is empty. 02:28.000 --> 02:32.830 So you can just call the service and you don't need to provide anything for the request. 02:32.830 --> 02:33.940 So let's try that. 02:33.940 --> 02:38.920 Let's do a Ros2 service call with slash clear. 02:39.430 --> 02:43.060 And then I should put just the S here and press tab. 02:43.450 --> 02:44.440 It should find it. 02:44.440 --> 02:51.080 And well we could put double quotes and an empty request like that. 02:51.110 --> 02:53.540 You could even omit it if you want. 02:53.570 --> 02:54.980 Let's press enter. 02:55.820 --> 02:57.020 And you see it's working. 02:57.020 --> 02:58.490 So what happened? 02:58.520 --> 03:00.020 You see, we have a log here. 03:00.020 --> 03:01.430 Clearing turtle sim. 03:01.430 --> 03:04.700 So there is a service server here that printed something. 03:04.880 --> 03:10.040 We make the request, we receive the response and the trace here is gone. 03:10.070 --> 03:12.890 Okay let's focus on this window again. 03:12.890 --> 03:14.720 Let's make the turtle move. 03:14.900 --> 03:16.820 You see we have a new trace. 03:16.910 --> 03:20.840 And if I call the service again here, it's gone. 03:20.870 --> 03:23.150 Okay, so this one is quite easy to use. 03:23.150 --> 03:27.200 And as you can see, as I told you, for service names you will use verbs. 03:27.200 --> 03:27.590 You see. 03:27.620 --> 03:28.160 Clear. 03:28.190 --> 03:28.670 Kill. 03:28.670 --> 03:29.120 Reset. 03:29.150 --> 03:29.900 Spawn. 03:29.930 --> 03:30.770 Set. 03:30.800 --> 03:31.610 Teleport. 03:31.640 --> 03:33.200 Those are verbs. 03:33.230 --> 03:34.730 Now let's see what. 03:34.730 --> 03:38.030 We don't need this node anymore. 03:38.030 --> 03:39.470 Let's try to use another one. 03:39.470 --> 03:43.070 So spawn is going to spawn a new turtle on the screen. 03:43.070 --> 03:45.320 So how can we use that one? 03:45.400 --> 03:50.560 rank two service type with spawn. 03:52.360 --> 03:52.870 Okay. 03:52.900 --> 03:55.570 And that's another interface. 03:55.570 --> 04:00.430 So you can see here we were using the package standard services. 04:00.520 --> 04:08.290 This one is from the package total SIM plus two interface show with spawn. 04:09.370 --> 04:11.860 And that one contains a bit more stuff. 04:11.860 --> 04:13.420 So you see we have the three dashes. 04:13.420 --> 04:17.200 So the request is here we have x, y and theta. 04:17.200 --> 04:19.960 So those are the coordinates for the turtle. 04:19.960 --> 04:22.720 So x is going to be here y is going to be here. 04:22.720 --> 04:25.180 And theta is the orientation of the turtle. 04:25.180 --> 04:27.220 And then we can provide a name if we want. 04:27.250 --> 04:28.480 That's optional. 04:28.480 --> 04:33.310 If you don't provide one a unique name you can see a unique name will be created. 04:33.310 --> 04:35.470 And then as the response you get the name. 04:35.470 --> 04:40.480 So either you've provided the name and you probably get the same one, or you're going to get the name 04:40.480 --> 04:42.620 that was generated for the turtle. 04:42.650 --> 04:47.900 Okay, so you see, we can guess a lot of stuff already using the command line tool with just a running 04:47.900 --> 04:48.230 node. 04:48.230 --> 04:50.120 And we don't have to check the code. 04:50.120 --> 04:56.300 So let's try to use this service Ros2 service call with spawn. 04:56.330 --> 04:58.550 And then we provide the interface. 04:58.550 --> 05:02.060 So from the package total sim let's put T and then tab. 05:02.060 --> 05:05.630 And then let's construct the request. 05:05.630 --> 05:09.470 So zero and zero starts at this point. 05:09.470 --> 05:13.190 If we put five and five it's going to be around the middle. 05:13.190 --> 05:17.990 So let's do x and then space 5.0 okay. 05:18.020 --> 05:20.600 That's a float number y. 05:20.630 --> 05:22.640 Let's put 5.0. 05:22.820 --> 05:26.210 And then well I don't want to provide theta okay. 05:26.240 --> 05:31.130 So theta is going to be zero I don't need to provide it I don't need to provide a name okay. 05:31.160 --> 05:32.330 I could leave it like that. 05:32.330 --> 05:34.520 But I'm going to choose the name. 05:34.520 --> 05:38.310 And let's use single quotes here because we are inside double quotes. 05:38.340 --> 05:40.710 Let's call it my turtle. 05:40.740 --> 05:42.810 Otherwise I think it's going to create. 05:42.930 --> 05:44.340 So this one is turtle one. 05:44.370 --> 05:46.680 And then it's going to create turtle two, etc.. 05:46.710 --> 05:48.270 Let's press enter here. 05:48.870 --> 05:55.290 And you see we have a new turtle that was spawned as coordinate five, five and zero means that it's 05:55.290 --> 05:57.810 just facing forward for the orientation. 05:57.810 --> 06:00.000 And as a response we get my turtle. 06:00.000 --> 06:02.160 And you see we have spawning turtle here. 06:02.160 --> 06:07.140 And finally we can use kill to remove that turtle. 06:07.140 --> 06:15.570 So let's see Ross two service type with kill. 06:16.320 --> 06:21.690 And we have the interface Ross two interface show. 06:21.750 --> 06:24.330 So you see it's always the same thing. 06:24.330 --> 06:28.320 So I encourage you to practice and use all the services you see here. 06:28.320 --> 06:28.830 We have. 06:28.830 --> 06:30.390 So this one is a bit easier. 06:30.390 --> 06:34.110 We just provide the name of the turtle and it's going to return nothing. 06:34.120 --> 06:36.250 so rushed to service. 06:36.250 --> 06:38.890 Call with kill. 06:39.190 --> 06:48.130 And then I put t, I press tab and then I put the request inside quotes and curly brackets name. 06:48.520 --> 06:51.100 And well we're going to use the same name. 06:51.100 --> 06:53.620 That's going to be my turtle okay. 06:53.620 --> 06:56.320 So my turtle. 06:56.470 --> 06:59.920 And let's see what we have okay. 06:59.950 --> 07:01.150 And the turtle is gone. 07:01.150 --> 07:03.850 We can do the same for the turtle one okay. 07:03.880 --> 07:05.380 That one is named turtle one. 07:05.380 --> 07:08.020 You can see here on the on the services. 07:08.020 --> 07:10.150 So I can do turtle. 07:12.520 --> 07:16.600 Turtle one and turtle one is gone as well. 07:16.630 --> 07:17.020 Great. 07:17.020 --> 07:22.000 So as you can see here, turtle SIM is great to practice with notes and all topics and services. 07:22.000 --> 07:26.350 If you want at this point to practice more, you can write some code to interact with the topics and 07:26.350 --> 07:27.130 services. 07:27.130 --> 07:31.240 In fact, that's what we will do in the final project of this course.