WEBVTT 00:00.110 --> 00:00.710 Hi everyone. 00:00.710 --> 00:01.280 Welcome back. 00:01.280 --> 00:06.530 In this section we will implement a real time use case using all the concepts we have learned so far. 00:06.560 --> 00:10.970 The example application that we are going to build is a online checkout application. 00:10.970 --> 00:15.800 Here the user submits the order details which will be received by the Checkout Service class here. 00:15.800 --> 00:20.030 Because each block that you see here is a representation of a class. 00:20.030 --> 00:24.260 So the checkout service is going to pass the order details to the payment service. 00:24.260 --> 00:29.840 So from the payment service, the payment call will be made to the appropriate bank to acquire the payment. 00:29.840 --> 00:34.940 And then the response will be sent back to the user stating the order is placed successfully. 00:34.970 --> 00:40.790 If there is an available credit or debit or rewards based on what type of payment option is being sent 00:40.790 --> 00:41.780 to the payment service. 00:41.780 --> 00:47.480 So what we are going to implement is a payment service using all the concepts we have learned so far. 00:47.510 --> 00:52.070 Okay, so with this information in place, let's go ahead and look at the project setup for the checkout 00:52.070 --> 00:56.750 service and the different domains that are involved in this online checkout application. 00:56.750 --> 00:57.740 So I'm back in IntelliJ. 00:57.770 --> 01:02.690 Here in the IntelliJ we'll be working on the checkout service for this specific section. 01:02.690 --> 01:08.120 So if you open the project if you expand to the main folder you will notice three different packages. 01:08.120 --> 01:13.440 Number one is a domain which has all the domain classes that are involved in the checkout service application. 01:13.440 --> 01:17.340 And then you'll notice a package named payment, which has a payment service. 01:17.370 --> 01:20.910 If you go ahead and take a look at the implementation, this is very simple and static. 01:20.940 --> 01:26.160 There is no code logic here because as part of this section, we are going to be implementing the payment 01:26.160 --> 01:29.220 service using all the concepts we have learned so far. 01:29.220 --> 01:33.810 So number three is if you go to the service package you have something called a checkout service. 01:33.810 --> 01:39.060 So the checkout service is the one which is going to orchestrate the whole call of receiving the order 01:39.060 --> 01:39.540 details. 01:39.540 --> 01:43.230 So we have this checkout order function which receives the order details. 01:43.230 --> 01:45.300 And then it makes a call to the payment. 01:45.300 --> 01:48.450 Once a payment response is received the payment is success. 01:48.450 --> 01:52.080 Then it is going to return the response as checkout success. 01:52.110 --> 01:55.260 Otherwise the response is going to be checkout failure. 01:55.290 --> 01:57.300 Let's quickly look at the domain over here. 01:57.300 --> 02:00.450 So in this case we receive the order details. 02:00.450 --> 02:04.620 So if you go and take a look at the order details this is of type record okay. 02:04.650 --> 02:06.180 And it holds three properties. 02:06.210 --> 02:07.620 Number one is the order ID. 02:07.650 --> 02:08.910 Number two is a card. 02:08.940 --> 02:11.070 Number three is a final amount. 02:11.070 --> 02:16.230 I kept the order line items out of this particular domain, because I want to keep this example really 02:16.230 --> 02:20.550 simple, because we don't need to worry about what the order line items are. 02:20.580 --> 02:25.300 What we care about is what is the final amount, and give me the card information so that we can actually 02:25.300 --> 02:27.220 go ahead and process the payment. 02:27.220 --> 02:31.360 And if you go ahead and take a look at the card class, this is again another card class. 02:31.360 --> 02:36.040 So we have not coded a record class that is referencing another record class yet. 02:36.040 --> 02:41.800 So this is a good example of how to reference a record class from another record class. 02:41.800 --> 02:44.110 This is actually pretty simple and straightforward. 02:44.110 --> 02:48.520 This is very similar to how you reference another Java class from your Java class. 02:48.520 --> 02:55.150 So in this case the card information has name, card number, verification code, expiry date and card 02:55.180 --> 02:55.570 type. 02:55.570 --> 02:58.570 So card type is interesting because this is going to drive. 02:58.570 --> 03:01.900 What are the different types of payment implementation that we need to write. 03:01.900 --> 03:05.920 So if you go to the card type we have credit debit and rewards. 03:05.920 --> 03:11.200 So our payment service should support all these different types of implementation. 03:11.200 --> 03:15.910 So these are the different domain classes that are going to be involved in our checkout service. 03:15.910 --> 03:20.170 So with this information let's quickly look at the design of how it's going to look like. 03:20.170 --> 03:23.980 Which means how the payment service design is going to be implemented. 03:23.980 --> 03:26.860 If you go to the next slide we have this payment service design. 03:26.860 --> 03:30.130 So the very first thing is we are going to have a payment gateway class. 03:30.160 --> 03:35.310 This is going to be a sealed abstract class, and that sealed abstract class is going to be providing 03:35.310 --> 03:40.080 the support for a debit card payment, rewards card payment and credit card payment. 03:40.080 --> 03:44.100 Because these are the three different card types that our domain supports, right? 03:44.130 --> 03:50.100 So if you go to the order details and if you go to the card and then the card type, we have three different 03:50.100 --> 03:56.010 types of card our checkout service supports in the future, if any other type comes in, we will add 03:56.010 --> 03:57.270 support for that one too. 03:57.300 --> 03:57.660 Okay. 03:57.690 --> 03:59.610 And then we have a payment factory class. 03:59.640 --> 04:03.450 This is going to be acting as a factory which accepts a card type. 04:03.450 --> 04:08.310 And then it's going to return you the appropriate payment instance class so that we can process the 04:08.310 --> 04:08.790 payment. 04:08.790 --> 04:12.540 So the payment service is going to be the entry point for the whole payment. 04:12.540 --> 04:16.200 From there the payment service is going to interact with payment factory. 04:16.200 --> 04:22.080 And then this is going to retrieve one of the instances of this payment implementation based on what 04:22.080 --> 04:23.160 that card type is. 04:23.190 --> 04:26.580 If you have issues trying to visualize this design, don't worry about it. 04:26.580 --> 04:32.490 In the next lecture, we will go step by step in implementing the payment service using all the concepts 04:32.490 --> 04:33.780 we have learned so far. 04:33.780 --> 04:34.800 So please hang on. 04:34.800 --> 04:37.260 We'll go ahead and implement this in the next lecture. 04:37.290 --> 04:38.670 This marks the end of this lecture. 04:38.700 --> 04:40.350 Catch you all in the next lecture. 04:40.350 --> 04:41.430 Thanks for watching.