1 00:00:00,360 --> 00:00:03,930 Instructor: Our next topic are response codes. 2 00:00:03,930 --> 00:00:07,860 So first, let's remember what a response code is. 3 00:00:07,860 --> 00:00:09,480 So, if you remember, 4 00:00:09,480 --> 00:00:12,360 we talked about a typical REST API response 5 00:00:12,360 --> 00:00:14,670 and we looked at this example. 6 00:00:14,670 --> 00:00:17,100 And when analyzing what we are seeing here, 7 00:00:17,100 --> 00:00:19,710 we see that one of the first thing 8 00:00:19,710 --> 00:00:22,500 in the response is the status. 9 00:00:22,500 --> 00:00:24,750 The status in this example is 200 10 00:00:24,750 --> 00:00:29,750 and we already said that 200 represent an okay status. 11 00:00:30,480 --> 00:00:34,307 And of course, there are the other parts of the response. 12 00:00:34,307 --> 00:00:38,040 So basically the responsibility of the response code 13 00:00:38,040 --> 00:00:42,840 is to notify the client about the status of the request, 14 00:00:42,840 --> 00:00:47,840 and specifically did it succeed the request and did it fail? 15 00:00:48,810 --> 00:00:51,810 And if it failed, then why? 16 00:00:51,810 --> 00:00:55,860 And if it failed, what kind of error occurred? 17 00:00:55,860 --> 00:00:59,043 And even more specifically, where was this error? 18 00:01:00,600 --> 00:01:04,980 Now, response codes are extremely important in API 19 00:01:04,980 --> 00:01:07,050 because most clients check 20 00:01:07,050 --> 00:01:09,960 for response code and then act accordingly. 21 00:01:09,960 --> 00:01:12,300 So if the client makes a request 22 00:01:12,300 --> 00:01:14,430 and gets back at 200, 23 00:01:14,430 --> 00:01:17,190 then the client knows that the request succeeded 24 00:01:17,190 --> 00:01:18,930 and it can now go and analyze 25 00:01:18,930 --> 00:01:21,450 the actual content of the request. 26 00:01:21,450 --> 00:01:24,420 But, if some other response code was received 27 00:01:24,420 --> 00:01:28,650 like 400 or 500, then the client usually knows 28 00:01:28,650 --> 00:01:30,690 that there was some kind of problem 29 00:01:30,690 --> 00:01:35,043 and it usually won't even try to analyze the response body. 30 00:01:36,510 --> 00:01:38,160 In addition, monitoring tools, 31 00:01:38,160 --> 00:01:40,680 and we will talk about monitoring later in this course, 32 00:01:40,680 --> 00:01:43,650 often check the response code and report it. 33 00:01:43,650 --> 00:01:46,590 So, from the monitoring tool point of view, 34 00:01:46,590 --> 00:01:49,680 if the monitoring request returned 200, 35 00:01:49,680 --> 00:01:51,300 then everything is fine. 36 00:01:51,300 --> 00:01:53,910 And if some other code was returned 37 00:01:53,910 --> 00:01:56,253 then there is some kind of problem. 38 00:01:57,540 --> 00:01:58,470 In addition, 39 00:01:58,470 --> 00:02:02,220 response codes makes the API easier to use and understand. 40 00:02:02,220 --> 00:02:04,710 So if a developer looks at the API 41 00:02:04,710 --> 00:02:06,480 and he sees the response code, 42 00:02:06,480 --> 00:02:09,060 then he can usually understand immediately 43 00:02:09,060 --> 00:02:10,080 what just happened. 44 00:02:10,080 --> 00:02:13,380 He shouldn't dig into some complicated error messages 45 00:02:13,380 --> 00:02:15,840 and look at stack trace and logging, et cetera. 46 00:02:15,840 --> 00:02:19,770 All he needs to do is to take a look at the response code. 47 00:02:19,770 --> 00:02:23,550 And, response codes are extremely easy to implement, 48 00:02:23,550 --> 00:02:26,610 and unfortunately, they are often overlooked. 49 00:02:26,610 --> 00:02:29,280 A lot of developers aren't even aware 50 00:02:29,280 --> 00:02:31,980 that there is something like a response code 51 00:02:31,980 --> 00:02:35,010 and they always return the same response code 52 00:02:35,010 --> 00:02:36,723 even if it is the wrong one.