WEBVTT 00:00.080 --> 00:05.930 In this lesson we will review how to introspect your last two services with the Ros2 command line. 00:05.930 --> 00:12.290 In fact, you've already seen most of the comments with Ros2 service list and Ros to service call. 00:12.290 --> 00:16.250 So you can open a terminal and you can type Ros2. 00:16.280 --> 00:17.540 Then we have service. 00:17.540 --> 00:21.710 If you press on tab twice, you will also see all of the possible. 00:21.710 --> 00:25.760 You see all of the possible subcommands for the Ros2 service. 00:25.760 --> 00:31.730 And if you do dash h, you also have kind of a small documentation with more information. 00:31.730 --> 00:36.380 So let's clear that and let's start a service server okay. 00:36.410 --> 00:38.000 We're going to introspect services. 00:38.000 --> 00:39.560 So we need a service. 00:39.560 --> 00:40.730 How to start a service. 00:40.730 --> 00:43.520 Well we create it when we create a server. 00:43.520 --> 00:50.660 So let's run our service server in for example the C plus plus package or the Python one. 00:50.660 --> 00:56.780 It doesn't matter add to int server okay. 00:56.810 --> 00:58.550 So we have the server running here. 00:58.550 --> 01:00.290 And now I can do ros two. 01:00.320 --> 01:07.850 So first let's do a Ros two node list just to show you once again that you can find from the node information. 01:07.850 --> 01:09.500 You can find the services. 01:09.500 --> 01:14.480 We can do ros2 node info with the node name. 01:14.930 --> 01:20.150 And you see in the service servers here we have the add to hints. 01:20.150 --> 01:23.420 So we have the name and the interface. 01:23.420 --> 01:25.610 So we have all the information already here. 01:25.640 --> 01:30.980 But then you can also find this service with Ros2 service list. 01:32.060 --> 01:33.800 You see we have the service here. 01:33.800 --> 01:40.040 And you can see that we have 1234567 additional services here. 01:40.040 --> 01:41.450 What are those services. 01:41.450 --> 01:44.990 Well most of them you see contain the word parameters. 01:44.990 --> 01:48.080 So this is for the parameter functionality. 01:48.110 --> 01:51.950 So we're going to see parameters in a future section in this course. 01:51.950 --> 01:59.690 And basically for each node that you start you also have a bunch of services that allow you to for example 01:59.690 --> 02:06.530 get parameters, modify parameters and stuff like that so that you will have for every node you create, 02:06.530 --> 02:09.900 you see that's the name of the node and then parameter. 02:09.900 --> 02:13.020 You also have here get type description. 02:13.020 --> 02:15.840 So you may have additional stuff. 02:15.840 --> 02:21.330 But basically if you didn't create it in your code, you see that it's been automatically generated 02:21.330 --> 02:23.310 and you will have those seven. 02:23.340 --> 02:27.990 Or maybe if they do an update and they add one more or they remove, well, you're going to have about 02:27.990 --> 02:32.010 seven services here for each node that you start. 02:32.040 --> 02:32.550 All right. 02:32.550 --> 02:38.490 So if we filter those out we can just see that this is the one that we have created. 02:38.490 --> 02:43.590 And then there is another command you can do ros2 service type. 02:44.400 --> 02:45.960 So type. 02:46.380 --> 02:54.000 And note that for topics it was Ros2 topic info for service it's Ros2 service type okay. 02:54.000 --> 03:00.090 It's not the same world and you can put the here service name. 03:00.270 --> 03:02.460 And we also get the type. 03:02.490 --> 03:02.700 Okay. 03:02.730 --> 03:06.450 You see it's the same thing we got with the Ros2 node info. 03:06.720 --> 03:10.620 And then how to see what's inside this interface. 03:10.620 --> 03:19.140 Well we have the Ros2 interface show, and you just put the name of the interface, and that's going 03:19.170 --> 03:20.790 to show you what's inside. 03:20.820 --> 03:21.000 Okay. 03:21.030 --> 03:22.470 So this we've already done it. 03:22.470 --> 03:26.610 So here you have the request three dashes and the response. 03:26.640 --> 03:27.120 All right. 03:27.120 --> 03:34.230 So knowing how to use those commands is very useful because let's say you start a service server that 03:34.230 --> 03:37.050 you haven't written and you don't know what's in the code. 03:37.080 --> 03:39.390 Then you see that we just started here. 03:39.390 --> 03:45.090 And then with Ros2 command line tools, we can find all the information we need so that we can create 03:45.120 --> 03:50.940 a client, for example, and so that we can call the service and we can even call the service from the 03:50.940 --> 03:51.480 terminal. 03:51.480 --> 03:56.700 So if the request is quite small here, you see we just have two easy fields. 03:56.700 --> 03:58.770 So just primitive data types. 03:58.770 --> 04:02.820 If the request is quite small here you see we just have two integers. 04:02.820 --> 04:05.910 Then that's going to be easy to create a request from the terminal. 04:05.910 --> 04:09.780 So in this case you can do ros2 service call. 04:09.780 --> 04:12.810 And then you will need to provide a few things in that order. 04:12.810 --> 04:15.990 So the first thing is the service name. 04:15.990 --> 04:16.000 Servicename. 04:16.000 --> 04:20.620 So add to int and you should use Autocompletion here. 04:20.650 --> 04:25.870 Okay, just so you don't make any typo after the name of the service, you need to provide the interface. 04:25.870 --> 04:30.910 And here you can just type the first letter and press tab and it's going to find it. 04:30.940 --> 04:31.330 Okay. 04:31.360 --> 04:35.470 Because it knows that for this service it needs that interface. 04:35.470 --> 04:41.290 So if you put the first 1 or 2 letters and then the tab doesn't work, it's probably because you have 04:41.290 --> 04:43.420 written that service name wrong. 04:43.420 --> 04:45.190 Or maybe it's not up okay. 04:45.220 --> 04:46.900 But use the Autocompletion here. 04:46.900 --> 04:49.750 So Ros2 service call name interface. 04:49.750 --> 04:55.780 And then if I press tab twice you see that we have. 04:55.780 --> 04:58.510 So we need to provide A and B. 04:58.990 --> 05:05.980 You see we have this kind of syntax here that's not really readable and not easy to use. 05:05.980 --> 05:13.690 So instead we can just use double quotes and create the request with curly brackets okay. 05:13.720 --> 05:15.550 And then put each field. 05:15.550 --> 05:18.640 So for example a and then colon. 05:18.730 --> 05:20.530 And then that's important. 05:20.530 --> 05:24.250 You have to put a space, because if you don't put a space, you're going to get an error here. 05:24.250 --> 05:26.200 And let's put a value. 05:26.230 --> 05:33.670 Then if you want to provide several parameters, you put another comma and then space and then B space 05:33.670 --> 05:34.990 seven for example. 05:34.990 --> 05:37.150 And we can press enter. 05:37.930 --> 05:38.980 It's going to create. 05:38.980 --> 05:40.420 So it's going to send a request. 05:40.450 --> 05:41.920 You see we have the request here. 05:41.920 --> 05:44.050 And then it's going to get the response. 05:44.050 --> 05:47.920 And note that you don't need to provide all the parameters here. 05:47.950 --> 05:50.830 If I just put a let's see what's going to happen. 05:50.980 --> 05:52.900 You see it's still working. 05:52.900 --> 06:00.250 If you don't provide a parameter in the request, you see that it's automatically set to zero for a 06:00.250 --> 06:00.670 integer. 06:00.670 --> 06:02.530 And for string is going to be an empty string. 06:02.560 --> 06:02.860 All right. 06:02.890 --> 06:06.040 So that's how you can call a service from the terminal. 06:06.040 --> 06:08.770 And you can test simple service servers. 06:08.800 --> 06:13.420 Now there is another way to call the service I'm going to show you with Rkt. 06:13.600 --> 06:15.880 So if you start Rkt. 06:17.950 --> 06:19.840 Okay maybe you have this. 06:19.870 --> 06:21.220 That was activity graph. 06:21.220 --> 06:23.870 You can close it here Okay. 06:23.870 --> 06:26.780 And we are back to this acute window. 06:26.810 --> 06:31.700 You can go on plugins and services service color. 06:32.540 --> 06:37.370 So I click here and you see we have well you can choose the service here. 06:37.370 --> 06:39.320 We're going to choose add to insert. 06:39.320 --> 06:45.200 And we have the service name the type and the different fields of the requests. 06:45.230 --> 06:45.740 Okay. 06:45.770 --> 06:53.600 And you can just double click here and let's say for three let's put the window here and let's call 06:53.600 --> 06:54.410 the service. 06:54.440 --> 06:56.360 You see we have a log on the server side. 06:56.360 --> 06:57.770 And we have the response here. 06:57.770 --> 07:01.160 So RCT can also be quite nice to use. 07:01.160 --> 07:02.660 That's a graphical tool. 07:02.660 --> 07:05.540 And also you don't need to write so much stuff on the terminal. 07:05.540 --> 07:07.970 You just put the different fields here okay. 07:08.000 --> 07:11.480 That's also going to work well for simple requests. 07:11.480 --> 07:15.680 So you can see to test service server you have lots of different choices. 07:15.680 --> 07:18.080 You can use the Ros2 service call in the terminal. 07:18.080 --> 07:19.040 You can use RCT. 07:19.130 --> 07:25.580 You can also use the script we have created with either Python or C plus, plus and modify the script 07:25.610 --> 07:28.070 to send the appropriate request.