WEBVTT 00:00.260 --> 00:04.130 Hey, everyone, and welcome back to the Knowledge Portal Video series. 00:04.160 --> 00:09.020 Now, in the earlier lecture we were discussing about the Http protocol. 00:09.020 --> 00:15.080 So continuing our journey with it today, we'll be understanding our first Http protocol method, which 00:15.080 --> 00:15.820 is get. 00:16.010 --> 00:18.770 So let's go ahead and understand more about it. 00:20.590 --> 00:28.750 So Http get request is a very simple method which is generally used to fetch the information which is 00:28.750 --> 00:30.160 specified in the request. 00:30.190 --> 00:30.640 Uri. 00:31.270 --> 00:35.710 So the syntax is get followed by the request uri. 00:35.740 --> 00:41.170 So if you're not aware what a request Uri is all about, let's take a very simple example for this. 00:42.010 --> 00:47.800 So I'll open up my atom editor and there are three URLs which are present over here. 00:47.830 --> 00:51.760 One is Dexter's labs in slash sample dot HTML. 00:51.790 --> 00:58.990 Then you have Dexter's labs in slash index.html and Dexter labs in slash video dot mp4. 00:59.290 --> 01:02.500 Now in all of these the first. 01:04.100 --> 01:07.340 Entity remains the same, which is Dexter Labs. 01:07.560 --> 01:14.510 And so you find that the server is the same and then you have a unique resource which you are mentioning 01:14.510 --> 01:14.930 over here. 01:15.140 --> 01:19.940 So this is the unique resource or a unique file is sample dot HTML. 01:20.060 --> 01:25.310 In the second request you have index dot HTML and the third request that is video dot mp4. 01:25.670 --> 01:33.590 So this specific parameter which signifies the unique file within the server is called as the request 01:33.620 --> 01:34.190 uri. 01:34.490 --> 01:36.290 So let's try this out. 01:36.290 --> 01:40.250 So I'll copy this and I'll paste it here. 01:40.610 --> 01:44.690 So now you have a sample dot HTML file. 01:44.840 --> 01:52.370 Let's modify this and put index dot HTML and you have a different page load altogether. 01:52.370 --> 01:54.220 So you have a different page over here. 01:54.230 --> 01:55.730 You have a different page over here. 01:55.880 --> 02:01.730 The reason is because here you are calling a file or a resource called a sample dot HTML. 02:01.760 --> 02:05.010 And here you are calling a resource called as index dot HTML. 02:05.970 --> 02:14.250 So the parameter which calls the unique resource within the server, in this case it is slash sample 02:14.250 --> 02:17.640 dot HTML is called as the request Uri. 02:19.080 --> 02:19.820 Perfect. 02:19.830 --> 02:23.340 So going back to our presentation. 02:23.430 --> 02:27.630 Get method is used along with the request uri. 02:27.810 --> 02:36.720 So when you talk about one of the example you have get slash admin followed by the http 1.1. 02:36.720 --> 02:40.400 So there are various Http protocols like 0.9. 02:40.410 --> 02:46.350 It all started with then you have 1.0, you have 1.1, and now even 2.0 is present. 02:46.440 --> 02:53.220 So depending upon the protocol language, which your browser is speaking, the protocol version might 02:53.220 --> 02:53.820 change one. 02:53.820 --> 03:01.410 Point one is a fairly common protocol version which is being used and in the next line you have host 03:01.410 --> 03:04.700 followed by Dexter dot CPU Labs dot n. 03:04.710 --> 03:12.840 So this entire request is interpreted as Dexter dot Labs dot n slash admin. 03:12.840 --> 03:15.270 So this is what it signifies. 03:15.540 --> 03:16.230 Perfect. 03:16.230 --> 03:18.440 So this is a very simple get request. 03:18.450 --> 03:25.020 There are various type of other get requests which is being used and one is called as the conditional 03:25.020 --> 03:25.780 get request. 03:25.800 --> 03:33.030 So conditional get method is generally used to fetch information with a specific condition. 03:33.030 --> 03:34.950 So let's take an example. 03:35.040 --> 03:39.270 You have get slash sample dot HTML. 03:39.300 --> 03:44.040 You have the Http protocol version, which is Http 1.1. 03:44.250 --> 03:55.620 Host this Dexter labs in and the condition here is if modified since Saturday 29th October 2017, followed 03:55.620 --> 03:57.210 by the time in GMT. 03:57.600 --> 04:07.920 So what is basically means get me sample dot HTML file from Dexter labs dot in server only if it is 04:07.920 --> 04:11.250 modified after this specific time. 04:11.460 --> 04:21.000 If it is if sample dot HTML is not modified after this specific amount of time, then the web server 04:21.000 --> 04:22.320 will send a 304. 04:22.350 --> 04:25.170 It will not fetch this specific resource. 04:25.170 --> 04:32.280 If it is modified, then the web server will send the entire sample dot HTML files content back to the 04:32.280 --> 04:32.940 client. 04:33.090 --> 04:35.430 So this is the conditional get. 04:35.730 --> 04:41.250 Let's talk about one more method which is partial get. 04:41.460 --> 04:49.680 So a partial get method is used to retrieve only specific content instead of everything by default. 04:50.130 --> 04:52.260 So let's take an example. 04:52.260 --> 05:02.160 You have get followed by the request url slash movie dot mp4, then http 1.1 and the host is Dexter 05:02.730 --> 05:03.480 Labs dot in. 05:03.480 --> 05:09.930 And in the third line there is one header which is added, which is range followed by bytes which is 05:09.930 --> 05:12.390 0/1 0 to 4. 05:12.600 --> 05:19.950 So what this basically means that I don't really need the entire movie dot mp4 file because it might 05:19.950 --> 05:21.450 be very big as well. 05:21.540 --> 05:29.370 I only need the first one 0 to 4 bytes of this specific movie dot mp4 file. 05:29.820 --> 05:32.970 And this is what a partial get means. 05:32.970 --> 05:38.070 It means give me only partial information instead of the entire file. 05:38.850 --> 05:40.710 So this is very useful. 05:40.710 --> 05:48.330 And in youtube.com you will see whenever you load a video, entire video is not streamed, only a specific 05:48.330 --> 05:50.670 information is streamed at the start. 05:50.730 --> 05:56.310 And when you complete it, then next range of information gets streamed. 05:56.640 --> 06:01.620 So we'll understand this with an example in the upcoming lecture. 06:01.620 --> 06:03.330 And let's do one thing. 06:03.370 --> 06:13.780 Let's write our first get request, not with the web browser, but with a manual handwritten request. 06:13.780 --> 06:20.410 So when you manually write things, it gives you a lot of satisfaction and it will help you understand 06:20.470 --> 06:22.540 things in more detail. 06:23.500 --> 06:26.320 So let's try this out. 06:28.360 --> 06:35.290 Let me check if I can zoom this more so that it will become much more visible. 06:35.530 --> 06:38.380 I hope this is much more visible now. 06:38.740 --> 06:47.000 So let's do a telnet on Dexter Labs dot in followed by the port. 06:47.020 --> 06:48.010 Port is 80. 06:48.040 --> 06:51.700 So 80 is the port in which the web server is listening. 06:52.630 --> 06:57.430 I'll press enter so it stays connected. 06:57.430 --> 07:04.630 And now since we are connected, we can write our first Http based request. 07:04.810 --> 07:16.210 So our request will be get slash sample dot HTML followed by the http 1.1. 07:16.840 --> 07:30.250 So we'll write this and now in the host we'll say Dexter dot Labs dot in, I'll press enter twice. 07:30.250 --> 07:37.180 And now you see the web server gave us a response saying that 200. 07:37.180 --> 07:37.450 Okay. 07:37.480 --> 07:38.050 200. 07:38.050 --> 07:38.400 Okay. 07:38.440 --> 07:46.120 Means that this request is successfully processed and it gave us range of headers. 07:46.570 --> 07:52.930 After giving the range of headers, it gave us the actual file, which is this is sample file. 07:52.930 --> 07:57.760 And then it states specially designed for your handwritten get request. 07:57.760 --> 08:04.190 And whenever you open this in the browser, you directly get this specific file. 08:04.190 --> 08:11.600 Browser in turn creates this specific Http request and sends it to the server. 08:11.630 --> 08:18.410 Now, instead of browsing, instead of browser formulating this request, we have actually written it 08:18.410 --> 08:20.480 in a handwritten format. 08:20.690 --> 08:31.100 So I hope you got the basic idea on how exactly the request is sent to the server and the response is 08:31.100 --> 08:32.000 received. 08:32.120 --> 08:41.180 So go ahead and try this out in your site as well so that it will give you a much more better understanding 08:41.180 --> 08:43.220 on how things would really work. 08:43.250 --> 08:46.460 So I hope this has been informative for you. 08:46.460 --> 08:53.420 And in the next lecture we will be speaking more about the conditional get and the partial get, and 08:53.420 --> 08:55.940 we'll look into how that would really work. 08:56.270 --> 08:58.100 So this is it about this lecture. 08:58.100 --> 09:02.750 I hope this has been informative for you and if you have any doubts, questions, suggestions, feel 09:02.750 --> 09:08.780 free to connect us at Twitter, Facebook or LinkedIn or email us at instructors at the Labs dot n. 09:08.870 --> 09:10.130 Thanks for watching.