WEBVTT 00:00.110 --> 00:00.680 Hi everyone. 00:00.680 --> 00:01.220 Welcome back. 00:01.220 --> 00:07.340 In this lecture we are going to learn about how to build an asynchronous client using the HTTP client 00:07.340 --> 00:09.170 that we have been using so far. 00:09.170 --> 00:13.730 So in this case we are going to use a similar function or a similar client. 00:13.730 --> 00:17.150 And then we are going to be creating a brand new function. 00:17.150 --> 00:21.920 The code is going to look pretty much the same, but the return type and the function that we are calling 00:21.920 --> 00:23.630 here is going to be a little different. 00:23.630 --> 00:26.660 So in this case I'm going to name this one as async okay. 00:26.690 --> 00:30.920 So in the place of send we are going to be calling send async. 00:30.920 --> 00:34.520 So the request arguments to this function is still the same. 00:34.520 --> 00:37.850 But the response is going to be a completable future. 00:37.850 --> 00:44.030 So if you go to the send async function it's going to return you a completable future of HTTP response. 00:44.030 --> 00:48.620 If you have not worked with Completablefuture, whatever I'm going to explain might not really make 00:48.620 --> 00:52.190 sense, but if you have already worked on it, it will be pretty easy to follow. 00:52.190 --> 00:54.710 I have a specific course on this specific topic. 00:54.710 --> 01:00.410 Please check my profile if you want to learn more in depth about how to use Completablefuture and what 01:00.410 --> 01:01.880 are the different options that you have? 01:01.910 --> 01:04.790 Okay, but in here, let's go ahead and get this started. 01:04.790 --> 01:07.720 So what we are going to do, we are going to use a response. 01:07.720 --> 01:10.450 So the response is an async response. 01:10.450 --> 01:10.930 Right. 01:10.930 --> 01:15.070 And then in order to access the actual response there are some functions. 01:15.070 --> 01:16.810 This is a functional API. 01:16.840 --> 01:20.050 So if you press dot it gives you all these options actually. 01:20.050 --> 01:22.780 So in our case we are going to be getting the response. 01:22.780 --> 01:26.500 And then we are going to apply the object mapper logic that we have over here. 01:26.500 --> 01:29.140 So in this case we can use a then apply. 01:29.140 --> 01:32.380 So then apply gives you access to the HTTP response. 01:32.380 --> 01:32.830 Right. 01:32.830 --> 01:34.360 So you can give any name you want. 01:34.390 --> 01:40.060 So in this case I'm going to give the name as HTTP response okay. 01:40.090 --> 01:44.050 And then what we are going to do we are going to be printing the HTTP status code. 01:44.050 --> 01:44.500 Right. 01:44.530 --> 01:47.080 So let's go ahead and copy that one and then put it over here. 01:47.080 --> 01:51.520 So this is going to be HTTP response okay. 01:51.550 --> 01:53.500 This is going to be HTTP response over here. 01:53.500 --> 01:55.540 So that we print the status code over here. 01:55.540 --> 01:56.920 And after that what do we do. 01:56.920 --> 02:02.110 So we need to still perform the logic of converting the string to a movie. 02:02.140 --> 02:02.560 Right. 02:02.560 --> 02:04.870 So we just need to put this logic over here. 02:04.870 --> 02:09.520 Because what we have access here is that here is a HTTP response. 02:09.520 --> 02:12.640 So let's go ahead and add the semicolon over here. 02:12.640 --> 02:13.630 We can remove this code. 02:13.630 --> 02:16.360 And it looks like we need to add the exception logic. 02:16.360 --> 02:18.640 Because there is a JSON processing exception. 02:18.640 --> 02:21.280 That can still happen if this parsing fails. 02:21.280 --> 02:25.030 So now let's go ahead and add the try and catch block over here. 02:25.060 --> 02:25.600 There you go. 02:25.600 --> 02:31.090 So this is to handle the exception that can be thrown from this actual deserialization okay. 02:31.120 --> 02:32.500 So now what we will do. 02:32.530 --> 02:34.180 We need to return this from here. 02:34.210 --> 02:34.420 Right. 02:34.450 --> 02:39.940 So in this case we can add the return over here because the response is going to be a computable future 02:39.940 --> 02:42.130 not the actual movie okay. 02:42.160 --> 02:46.060 So in this case we're going to add compatible future movie over here. 02:46.060 --> 02:49.060 So let me quickly recap what we have done so far here. 02:49.060 --> 02:53.110 So what we have done here is that we have changed the send call to send async. 02:53.110 --> 02:57.850 When we make this call, what this is going to return is a this is going to return you a computable 02:57.850 --> 02:58.360 future. 02:58.360 --> 03:04.210 So once we have the handle of computable future, what this is going to do this is going to hold the 03:04.210 --> 03:04.630 future. 03:04.630 --> 03:10.270 Which means any time when this code completes this particular logic, whatever we have in the then apply 03:10.270 --> 03:11.290 will get invoked. 03:11.290 --> 03:16.950 And what this send async also means is that when the caller makes a call to the specific function. 03:16.980 --> 03:21.510 The thread that's involved in executing this code is not going to be blocked anymore. 03:21.540 --> 03:26.400 As soon as this call is executed, the thread will be released and then a future will be returned. 03:26.400 --> 03:28.170 So we have a handle of this future. 03:28.170 --> 03:33.570 When that future completes, then we will use the logic that we have here to be executed. 03:33.570 --> 03:37.410 Once this logic is executed, the Completablefuture will be executed. 03:37.440 --> 03:37.800 Okay. 03:37.830 --> 03:41.850 And in here, what we are going to do, we are going to be calling the test function over here. 03:41.850 --> 03:45.090 So we are going to call the get movie id async. 03:45.120 --> 03:45.540 There we go. 03:45.570 --> 03:49.080 Let's copy this one and then put it over here and then put it over here. 03:49.080 --> 03:52.200 So in this case what we have is a compatible feature right. 03:52.200 --> 03:54.450 So all these assertions will fail here. 03:54.450 --> 03:57.540 So in this case what we can do we can actually call Dot. 03:57.540 --> 04:00.630 And you have many functions so that we can actually get the data. 04:00.630 --> 04:02.520 What's present in the compatible feature. 04:02.520 --> 04:06.600 Since we are using the test cases we can very well invoke the join function. 04:06.600 --> 04:11.490 So what this join function will do is that it will wait for that compatible feature to complete. 04:11.490 --> 04:16.980 And then we will basically have a handle of that object that is present inside the compatible feature. 04:16.980 --> 04:22.300 And then we are actually performing the assertions as we have done for the synchronous call. 04:22.300 --> 04:25.840 So now what I'm going to do I'm going to be executing this test. 04:27.310 --> 04:29.770 And this test is going to pass as expected. 04:29.770 --> 04:34.120 So one thing you need to make sure is that you need to have the J-web server up and running. 04:34.150 --> 04:38.050 As long as that's up and running you're going to see a green check mark over here. 04:38.080 --> 04:38.680 There you go. 04:38.710 --> 04:41.410 This test case succeeded as expected. 04:41.410 --> 04:46.870 So in this lecture what we have learned is that we have learned how to build an asynchronous HTTP client, 04:46.870 --> 04:49.750 which is by calling the send async function. 04:49.750 --> 04:53.140 So once you call the send async function, what you get is a comparable feature. 04:53.140 --> 04:58.720 And then you implement the handle of that specific response using the then apply function. 04:58.720 --> 05:01.090 So there are many ways of handling exceptions. 05:01.090 --> 05:04.570 Also I'm not going to cover those things as part of this course. 05:04.570 --> 05:09.460 If you want to learn about Completablefuture in detail, I have a specific course named multithreading 05:09.460 --> 05:12.430 Parallel and Asynchronous Coding in modern Java. 05:12.430 --> 05:14.680 So this is a pretty popular course in Udemy. 05:14.710 --> 05:19.000 You're welcome to enroll and then learn more about Completablefuture in this specific course. 05:19.000 --> 05:24.160 If you go to the bottom, there is a or there are many section that talks about comparable feature in 05:24.160 --> 05:24.760 detail. 05:24.760 --> 05:26.170 This marks the end of this lecture. 05:26.170 --> 05:27.340 Thank you for watching.