1 00:00:02,050 --> 00:00:05,920 Now, that is where REST APIs come into play. 2 00:00:05,920 --> 00:00:10,920 This is a specific pattern of building URL-based APIs. 3 00:00:10,920 --> 00:00:13,510 So when you say that you build a REST API, 4 00:00:13,510 --> 00:00:18,020 you build such a URL-based API by following certain rules, 5 00:00:18,020 --> 00:00:21,220 which are not officially standardized, 6 00:00:21,220 --> 00:00:23,303 but common ground, you could say. 7 00:00:24,520 --> 00:00:28,600 REST stands for representational state transfer, 8 00:00:28,600 --> 00:00:30,640 but it's not too important actually, 9 00:00:30,640 --> 00:00:33,120 what's more important is how it actually works 10 00:00:33,120 --> 00:00:35,740 and how you build REST APIs. 11 00:00:35,740 --> 00:00:39,030 And whilst there are more details to it, 12 00:00:39,030 --> 00:00:40,660 which you can dive into, 13 00:00:40,660 --> 00:00:43,910 there is one really important core rule, 14 00:00:43,910 --> 00:00:46,730 which you will see in all REST APIs 15 00:00:46,730 --> 00:00:50,560 or APIs that call themselves REST APIs out there. 16 00:00:50,560 --> 00:00:53,330 Because REST indeed is the most popular 17 00:00:53,330 --> 00:00:55,410 and common form of building APIs, 18 00:00:55,410 --> 00:00:58,180 and you will therefore for see it a lot. 19 00:00:58,180 --> 00:01:01,240 Now, that one rule which I mentioned is in the end 20 00:01:01,240 --> 00:01:03,760 that you have these endpoints, 21 00:01:03,760 --> 00:01:07,460 these URL, HTTP method combinations, 22 00:01:07,460 --> 00:01:11,520 and every such endpoint maps to a certain action. 23 00:01:11,520 --> 00:01:14,810 For example, we could have an endpoint, a route, 24 00:01:14,810 --> 00:01:18,670 in our backend code, where we expect a GET request 25 00:01:18,670 --> 00:01:23,670 to a path named /cars, so our domain /cars. 26 00:01:24,581 --> 00:01:27,100 And for incoming GET requests to this path, 27 00:01:27,100 --> 00:01:30,730 we might then return a list of available cars. 28 00:01:30,730 --> 00:01:34,330 For example, if we're building a car rental service, 29 00:01:34,330 --> 00:01:37,260 then this could be one of our endpoints. 30 00:01:37,260 --> 00:01:39,580 And of course, we could have more endpoints, 31 00:01:39,580 --> 00:01:43,470 and we could have a bunch of HTTP method, URL 32 00:01:43,470 --> 00:01:48,210 or path combinations that then trigger different actions. 33 00:01:48,210 --> 00:01:51,520 Besides the GET /cars, example I already showed you, 34 00:01:51,520 --> 00:01:54,140 we could, for example, except POST requests 35 00:01:54,140 --> 00:01:58,150 to our domain.com/rental, 36 00:01:58,150 --> 00:02:01,640 which could create a new rental request, 37 00:02:01,640 --> 00:02:04,020 if we are building a car rental service, 38 00:02:04,020 --> 00:02:07,020 and then of course, return a response that contains 39 00:02:07,020 --> 00:02:11,810 whether the request was confirmed or declined, for example. 40 00:02:11,810 --> 00:02:15,560 We could accept PUT requests to a rental process 41 00:02:15,560 --> 00:02:17,950 that has a certain ID assigned to it, 42 00:02:17,950 --> 00:02:22,160 which would allow us to update that rental data piece 43 00:02:22,160 --> 00:02:25,820 or a PATCH request to update some user data 44 00:02:25,820 --> 00:02:30,110 or a DELETE request to cancel the rental of a car. 45 00:02:30,110 --> 00:02:32,440 And these are just some dummy examples, 46 00:02:32,440 --> 00:02:35,490 but the idea hopefully is clear. 47 00:02:35,490 --> 00:02:39,470 We build such a Web service as a REST API 48 00:02:39,470 --> 00:02:41,670 by defining a couple of routes 49 00:02:41,670 --> 00:02:45,960 where the HTTP method path combination is very important, 50 00:02:45,960 --> 00:02:50,780 and then our users, our customers, of our service, 51 00:02:50,780 --> 00:02:54,410 can send requests to these specific endpoints 52 00:02:54,410 --> 00:02:59,260 to trigger certain actions or get back certain responses. 53 00:02:59,260 --> 00:03:02,240 That's the idea behind REST APIs in the end, 54 00:03:02,240 --> 00:03:06,510 and that, as mentioned, is the most common form of APIs, 55 00:03:06,510 --> 00:03:10,650 the most common approach of building Web APIs. 56 00:03:10,650 --> 00:03:13,660 Nonetheless, there is something which I have highlighted 57 00:03:13,660 --> 00:03:16,853 before in the course, which I wanna highlight again. 58 00:03:17,870 --> 00:03:20,970 Even though we have all these nice combinations here, 59 00:03:20,970 --> 00:03:24,750 it's still the backend code dead really matters in the end. 60 00:03:24,750 --> 00:03:28,940 It's the backend code that decides what actually happens. 61 00:03:28,940 --> 00:03:31,390 Of course, we have these endpoints 62 00:03:31,390 --> 00:03:34,890 and we set them up following certain conventions. 63 00:03:34,890 --> 00:03:37,110 For example, we would create a endpoint 64 00:03:37,110 --> 00:03:39,070 in our route configuration 65 00:03:39,070 --> 00:03:43,470 that wants the DELETE request method for deleting some data, 66 00:03:43,470 --> 00:03:45,300 but these are just conventions. 67 00:03:45,300 --> 00:03:48,170 What actually happens on our server 68 00:03:48,170 --> 00:03:51,710 is only decided by our backend code. 69 00:03:51,710 --> 00:03:54,270 We could theoretically set up a route 70 00:03:54,270 --> 00:03:57,590 that wants a GET request to a certain path 71 00:03:57,590 --> 00:04:00,640 where we then delete some data on the backend, 72 00:04:00,640 --> 00:04:02,800 this just wouldn't make sense. 73 00:04:02,800 --> 00:04:06,310 So as the developer creating such a Web service, 74 00:04:06,310 --> 00:04:08,950 we typically come up with endpoints, 75 00:04:08,950 --> 00:04:13,540 so with request method, URL or path combinations 76 00:04:13,540 --> 00:04:16,470 that also give the sender of the request 77 00:04:16,470 --> 00:04:19,523 a clear idea of what is likely to happen. 78 00:04:22,150 --> 00:04:23,250 Of course, in addition, 79 00:04:23,250 --> 00:04:25,950 we should also provide clear documentation, 80 00:04:25,950 --> 00:04:29,440 written documentation, if we plan on selling a service 81 00:04:29,440 --> 00:04:32,620 to others, but the endpoints should already give 82 00:04:32,620 --> 00:04:35,963 a first clue of what's probably going to happen. 83 00:04:37,040 --> 00:04:38,660 Now, in this course section, 84 00:04:38,660 --> 00:04:42,150 we're going to learn how to build such a REST API, 85 00:04:42,150 --> 00:04:43,280 because as mentioned, 86 00:04:43,280 --> 00:04:46,460 that is the most common form of an API. 87 00:04:46,460 --> 00:04:50,160 I still also wanna mention that there are alternatives 88 00:04:50,160 --> 00:04:53,300 because the REST is just a pattern for building Web APIs, 89 00:04:53,300 --> 00:04:56,090 and of course, there are also different patterns. 90 00:04:56,090 --> 00:05:00,020 Alternatives would, for example, be the SOAP API, 91 00:05:00,020 --> 00:05:03,800 though, to be very honest, that's not too important anymore, 92 00:05:03,800 --> 00:05:06,170 you don't really need to learn that 93 00:05:06,170 --> 00:05:08,660 unless you really work on a project 94 00:05:08,660 --> 00:05:11,360 where you are forced to use that, 95 00:05:11,360 --> 00:05:14,860 but a very popular alternative to REST APIs 96 00:05:14,860 --> 00:05:17,840 are GraphQL APIs. 97 00:05:17,840 --> 00:05:20,820 This is a pattern developed by Facebook, 98 00:05:20,820 --> 00:05:24,380 and here, for example, you don't have different endpoints 99 00:05:24,380 --> 00:05:28,250 with different request method path combinations. 100 00:05:28,250 --> 00:05:31,360 Instead, there you have just one endpoint, 101 00:05:31,360 --> 00:05:34,800 which is a POST request to some path of your choice, 102 00:05:34,800 --> 00:05:37,670 and then it's the data that's part of the request 103 00:05:37,670 --> 00:05:41,310 that describes what should happen on the server. 104 00:05:41,310 --> 00:05:43,200 It's a totally different topic. 105 00:05:43,200 --> 00:05:47,230 I do dive into GraphQL APIs in my NodeJS course, 106 00:05:47,230 --> 00:05:49,510 if you're interested in that, but still, 107 00:05:49,510 --> 00:05:53,990 as I mentioned before, REST APIs or APIs that are similar 108 00:05:53,990 --> 00:05:58,450 to the concepts implied by the REST API approach 109 00:05:58,450 --> 00:06:01,760 are the most common form of APIs, and therefore, 110 00:06:01,760 --> 00:06:04,310 that's what we'll dive into in this course section. 111 00:06:05,250 --> 00:06:08,000 And with that enough of the theory, 112 00:06:08,000 --> 00:06:10,300 we're now going to get our hands dirty 113 00:06:10,300 --> 00:06:13,160 and build our first API together now, 114 00:06:13,160 --> 00:06:16,660 and for then, we're going to start with a simple example 115 00:06:16,660 --> 00:06:19,460 and we're going to build our own Web service 116 00:06:19,460 --> 00:06:24,460 with a web-based API that allows users of that service, 117 00:06:24,560 --> 00:06:28,690 no matter if that's ourselves on our decoupled frontend 118 00:06:28,690 --> 00:06:31,860 or other developers with their own sites, 119 00:06:31,860 --> 00:06:36,780 to send requests to that API to get a daily quote. 120 00:06:36,780 --> 00:06:38,940 So when our request reaches this route, 121 00:06:38,940 --> 00:06:42,413 we wanna retrieve and return a random daily quote. 122 00:06:43,440 --> 00:06:45,870 Now, we're not going to add endpoints 123 00:06:45,870 --> 00:06:49,960 for storing daily quotes because that's not a feature 124 00:06:49,960 --> 00:06:52,550 this service will provide to our customers. 125 00:06:52,550 --> 00:06:54,360 Instead, the that is something which we, 126 00:06:54,360 --> 00:06:56,770 as the service administrator, 127 00:06:56,770 --> 00:06:59,510 could do through some other API, 128 00:06:59,510 --> 00:07:01,660 which is not exposed to the public, 129 00:07:01,660 --> 00:07:05,210 or as we will do it here, by directly manipulating 130 00:07:05,210 --> 00:07:08,400 the database with database queries. 131 00:07:08,400 --> 00:07:10,150 This is what we're going to build, 132 00:07:10,150 --> 00:07:12,130 and we're going to build it from the ground up 133 00:07:12,130 --> 00:07:15,670 with Node, Express and MongoDB, though, of course, 134 00:07:15,670 --> 00:07:18,100 I wanna emphasize that you could use 135 00:07:18,100 --> 00:07:22,090 any programming language, any framework for that language, 136 00:07:22,090 --> 00:07:24,940 and of course, also any database. 137 00:07:24,940 --> 00:07:28,610 You could also build Web APIs with MySQL. 138 00:07:28,610 --> 00:07:30,773 That would work just fine as well.