WEBVTT 00:00.080 --> 00:06.080 Let's now create a Cplusplus service client for the service server we have created just before. 00:06.080 --> 00:12.890 And as we did with Python, we will first start with kind of a script with no OOP to see the different 00:12.890 --> 00:20.720 steps of the client, and then we will integrate the client inside an OOP node in the next video. 00:20.720 --> 00:22.400 So let's create. 00:23.150 --> 00:29.210 Let's go to our workspace the C plus plus package and source. 00:29.360 --> 00:39.410 Let's add an add to its client no OOP dot cpp. 00:39.410 --> 00:41.510 So I'm using the same name here. 00:41.510 --> 00:44.180 We are going to create the client in that file. 00:44.210 --> 00:48.410 Let's go back to VS code. 00:48.410 --> 00:55.580 And we have the file here I'm still going to start from the template but I'm going to modify it. 00:55.580 --> 00:57.770 So I take the template code. 00:58.190 --> 01:02.390 And I'm not going to use this class. 01:04.550 --> 01:04.970 Okay. 01:05.000 --> 01:13.400 I'm just going to create a node that's going to be this time an rcl cp node. 01:14.030 --> 01:20.000 Okay I need to provide the name add to hint client. 01:20.030 --> 01:23.240 Let's name it no OP. 01:25.190 --> 01:25.730 Okay. 01:25.730 --> 01:28.070 And I'm going to remove this pin as well. 01:28.070 --> 01:29.930 We're not going to make the speed like that. 01:29.990 --> 01:33.560 And let's actually save to get the Autocompletion for Slcp. 01:34.160 --> 01:34.520 Okay. 01:34.520 --> 01:37.730 And let's start from this and let's create a client. 01:37.730 --> 01:41.810 So we will start by initializing Ros2 communications. 01:41.810 --> 01:44.150 Then we create a node. 01:44.180 --> 01:46.370 It's going to be a shared pointer to a node. 01:46.520 --> 01:47.750 We're going to write our code. 01:47.750 --> 01:50.270 And at the end we shut down Ros2. 01:50.270 --> 01:54.080 So let's create a client I'm going to just use the auto keyword. 01:54.080 --> 01:59.780 Again client is equal to and we're going to use the node object here. 01:59.780 --> 02:05.630 And in the node we have the functionality create client as simple as that. 02:05.630 --> 02:08.780 And we need, of course, to provide an interface. 02:08.780 --> 02:19.430 So I'm also going to include the interface which is example interfaces solve and add to instance HPP. 02:19.430 --> 02:23.060 And let's let's save right now to get the auto completion okay. 02:23.090 --> 02:28.610 So it's important that you use the same interface in the server and in the client of course. 02:28.610 --> 02:32.600 So when we create the client it's going to be a template for the interface. 02:32.600 --> 02:35.210 So we provide an interface here. 02:35.270 --> 02:42.500 Example interfaces solve add to ints like that. 02:42.500 --> 02:45.230 And then we need to open the parentheses. 02:45.230 --> 02:48.950 And in this that's going to be the name of the service. 02:48.950 --> 02:52.040 So if we go back here what was the name of the service. 02:52.070 --> 02:54.740 It's add to int right here. 02:55.310 --> 03:02.780 So I will just use the same name for the client and the server so that they can communicate. 03:02.810 --> 03:03.170 All right. 03:03.170 --> 03:03.920 So two things. 03:03.920 --> 03:08.090 To create the client you need the interface and the a name as always. 03:08.120 --> 03:13.850 Then we are going to also wait for the service to be up, because if you try to send the request and 03:13.850 --> 03:16.670 the server is not up, then you're going to get an error. 03:16.670 --> 03:18.860 So let's do here a while. 03:19.220 --> 03:21.620 Not client. 03:22.220 --> 03:23.060 Wait. 03:23.060 --> 03:27.260 So you see I use an error because of course that's going to be a shared pointer. 03:27.860 --> 03:33.320 So wait for service and we need to provide a timeout. 03:33.320 --> 03:44.840 I'm just going to be using here namespace std chrono literals. 03:45.290 --> 03:48.050 And let's say one second. 03:49.610 --> 03:54.470 So basically wait for service is going to return true if the service is found. 03:54.470 --> 03:57.200 But then if it's not found it's going to wait. 03:57.290 --> 04:00.410 If you provide a timeout it's going to wait until the timeout. 04:00.410 --> 04:06.950 So one second if after one second the service is not found, that's going to return false. 04:06.980 --> 04:10.130 And so with the negation here is going to become true. 04:10.130 --> 04:16.070 And so as long as the server is not up every one second, we can do something. 04:16.100 --> 04:18.260 For example, print clcp. 04:18.770 --> 04:35.150 This time I can use Clcp one okay node get logger and we're going to print waiting for the server okay. 04:35.150 --> 04:38.540 You can just add whatever you want okay. 04:38.570 --> 04:42.890 And after this line we know that the server is found. 04:42.890 --> 04:50.960 So if the server is found we can create a request and send a request I'm going to do auto request is 04:50.960 --> 04:51.800 equal to. 04:51.830 --> 04:54.980 And we are going to create a request object. 04:54.980 --> 04:57.440 And actually not just a request object. 04:57.440 --> 05:01.010 But we need to do STD make shared. 05:01.010 --> 05:11.480 So we're going to create a shared pointer to a request object which is example interfaces SRB And two 05:11.510 --> 05:14.570 ints and then we add requests. 05:14.570 --> 05:16.430 You see we have request and response. 05:16.430 --> 05:19.400 So we have two messages inside this interface. 05:19.430 --> 05:22.280 Close the bracket and then we have parentheses. 05:22.310 --> 05:26.900 And so here is a quite big difference when you create a request. 05:26.900 --> 05:32.540 So in C plus plus when you create a request message or if you create if I go back to for example the 05:32.540 --> 05:33.980 number publisher. 05:34.010 --> 05:39.830 You see when you create a message for a topic, you see we don't create a shared pointer. 05:39.830 --> 05:43.250 We just create the object itself and then we publish it. 05:43.250 --> 05:50.630 That's the difference here in a service client we create a shared pointer of the request. 05:50.630 --> 05:54.260 So this is a small inconsistency here in C plus plus okay. 05:54.290 --> 06:00.920 And now we have our request we can request a with an arrow is equal to. 06:00.950 --> 06:03.230 Let's give a number six. 06:04.010 --> 06:10.700 For example request B is equal to two. 06:11.180 --> 06:12.710 So the sum should be eight. 06:12.750 --> 06:18.270 and then we are going to use the client to send the request to the server. 06:18.270 --> 06:22.050 And here we have the async send request. 06:22.050 --> 06:28.020 So we're going to use the asynchronous call so that then we can spin until we get the response. 06:28.020 --> 06:33.120 So async send request I give the shared pointer to the. 06:33.150 --> 06:37.470 So I give the request here which is the shared pointer to the request object. 06:37.470 --> 06:40.320 And that's going to return a future. 06:40.320 --> 06:43.770 And I can use the auto keyword again. 06:43.800 --> 06:46.860 You see that's going to be a future here. 06:47.190 --> 06:54.030 Well that's a that's a client future object something that's specific to Ros2. 06:54.060 --> 07:02.820 And then I can do a clcp spin but not spin spin until future complete. 07:03.300 --> 07:08.220 And I will need to pass first the node because we need to make the node spin. 07:08.220 --> 07:10.140 And for what future? 07:10.140 --> 07:16.650 For the future we have just created here, which is the one we get from the async send request function. 07:16.680 --> 07:17.520 All right. 07:17.520 --> 07:23.490 And then after this returns then we can try to get the response. 07:23.490 --> 07:29.670 So let's do auto response is equal to future dot get okay. 07:29.700 --> 07:32.790 That's how you get the response. 07:32.910 --> 07:36.480 And you can see here we get a shared pointer. 07:36.510 --> 07:42.390 Actually not just the response but a shared pointer to the add to insert response. 07:42.690 --> 07:43.230 All right. 07:43.230 --> 07:53.460 And then if you want you can print a CSP info this get logger. 07:56.700 --> 07:59.280 Oh actually it's not this it's node. 07:59.280 --> 08:00.600 We are not in a class. 08:00.600 --> 08:02.250 We use the node here. 08:02.940 --> 08:06.570 And then I think I've already written that here. 08:06.570 --> 08:10.830 You see we can just do the sum. 08:11.070 --> 08:17.880 I'm just going to take that code and use it there Okay. 08:20.130 --> 08:22.290 So we print the request A plus. 08:22.290 --> 08:28.170 The request b is equal to the response sum that we get after the spinning. 08:28.200 --> 08:28.980 All right. 08:28.980 --> 08:30.900 And the program is complete. 08:30.930 --> 08:31.890 Let's save. 08:31.920 --> 08:33.630 Let's just do a quick recap. 08:34.050 --> 08:35.910 So we initialize rows to communications. 08:35.910 --> 08:37.920 We start a node. 08:37.920 --> 08:40.050 From the node we create a client. 08:40.200 --> 08:42.630 We wait for the service to be up. 08:42.690 --> 08:46.770 After the service is up we can create a request. 08:46.800 --> 08:49.020 We send the request asynchronously. 08:49.020 --> 08:55.440 And then we're going to make the node spin until that future is complete okay. 08:55.470 --> 09:00.780 So the future we get after we send the request then we get the request from the future. 09:00.780 --> 09:03.960 And well then you just do whatever you want with the response. 09:03.960 --> 09:07.380 Let's add an executable to test that. 09:07.710 --> 09:15.630 So another one here add executable add to its client. 09:16.290 --> 09:21.810 No, OOP is quite a long name from SK. 09:22.170 --> 09:26.730 Add two ints client no oop cpp. 09:26.760 --> 09:38.700 That's the file name and an amount target dependencies with this executable name and what dependencies 09:38.700 --> 09:43.620 we need are clcp of course and example interfaces. 09:44.640 --> 09:47.700 Let's not forget to install the executable. 09:47.730 --> 09:50.160 Add two ints client. 09:50.190 --> 09:51.570 No OOP here. 09:51.780 --> 09:56.130 Okay so once again we add those two lines and that one here. 09:56.430 --> 09:57.810 Let's save everything. 09:57.810 --> 10:04.620 And let's go back to the terminal to build the package. 10:05.490 --> 10:11.430 So let's do a call on build I should have the the command with packages. 10:11.430 --> 10:14.010 Select my C plus plus package. 10:15.750 --> 10:16.680 Okay. 10:16.680 --> 10:21.700 And let's well let's use those terminals I'm just going to use that one. 10:23.530 --> 10:28.900 Actually the both terminals, because we have just built and we have a new node. 10:28.900 --> 10:30.220 And let's start here. 10:30.250 --> 10:38.440 Ros to run my CPP package with add two ints client no OOP. 10:38.620 --> 10:40.480 So that's the C plus plus one right. 10:40.480 --> 10:42.100 That's the one we've just written. 10:42.100 --> 10:48.250 And this we should see a log a warning log waiting for the server because there is no server. 10:48.280 --> 10:50.350 Now I'm going to start the server here. 10:50.530 --> 10:52.720 So the C plus plus server for example. 10:53.470 --> 10:57.580 And you see as soon as I start the server it's been found on the client. 10:57.610 --> 11:00.370 The client will send a request. 11:00.400 --> 11:06.160 It's received by the server which processes the request, sends back the response, and then we get 11:06.160 --> 11:07.720 the response on the client side. 11:07.750 --> 11:08.110 Great. 11:08.110 --> 11:14.590 So you have seen the mechanism for the C plus plus client, which is exactly the same as the Python 11:14.590 --> 11:14.830 one. 11:14.860 --> 11:14.980 Okay. 11:15.010 --> 11:18.910 That's the same behavior as we did for the Python client. 11:18.910 --> 11:21.160 And to recap here this code. 11:21.160 --> 11:27.900 So that's not a normal OOP code for rust, but this code is very useful to test services very fast. 11:27.930 --> 11:33.000 Okay, if you have a service server and a request is a bit too complicated to use in the terminal, 11:33.000 --> 11:36.750 then you just use this as a template and you can just test your server. 11:36.750 --> 11:41.100 In fact, for just that script, you could even just use the Python script. 11:41.130 --> 11:42.690 Okay, you don't even need this C plus. 11:42.690 --> 11:44.160 Plus that was just for the example. 11:44.160 --> 11:50.640 But you could use the where is it that script here in Python if you have written that okay. 11:50.640 --> 11:55.200 Because it's just for testing purposes, you're not going to use that in your application in your end 11:55.230 --> 11:56.010 application. 11:56.010 --> 12:00.120 So for just testing purposes you could just use the Python one. 12:00.120 --> 12:00.930 And why is that? 12:00.930 --> 12:05.760 Because if you use Simulink install then you can just modify the code and make different tests. 12:05.760 --> 12:08.010 And you don't need to build every time. 12:08.010 --> 12:09.690 So it's going to be much faster. 12:09.720 --> 12:09.960 Okay. 12:09.990 --> 12:14.850 So for this example the C plus plus one is actually not really needed. 12:14.850 --> 12:19.140 But now you know how to write a C plus plus client without OOP. 12:19.170 --> 12:25.980 Let's see the OOP version which is what you will use in the nodes that you write for your future applications.