WEBVTT 00:00.230 --> 00:04.280 Hey, everyone, and welcome back to the Knowledge Portal Video series. 00:04.280 --> 00:08.330 And in today, we'll be speaking about the head method. 00:08.360 --> 00:14.690 Now, we already had an overview about the head method in the earlier lectures when we ran Curl Hyphen 00:14.870 --> 00:21.260 Command, however, I decided to just have a dedicated lecture so that it will become easier for us 00:21.260 --> 00:22.040 to revise. 00:23.660 --> 00:32.410 So when you talk about a response which a web server will send, there are two parts in the response. 00:32.420 --> 00:36.320 One is the header fields and second is the message body. 00:36.320 --> 00:42.620 And this is very important because whenever a web server will send a response, if the first thing that 00:42.620 --> 00:48.830 it will show is the header field and after the header field, it will give us the message body if it 00:48.830 --> 00:49.760 is required. 00:49.910 --> 00:57.800 Now header field itself gives a lot of information like in here you say you see it is 200. 00:57.800 --> 00:58.010 Okay. 00:58.010 --> 01:01.080 That means the request has been successfully processed. 01:01.500 --> 01:05.220 Along with that you have various other important information like the date. 01:05.220 --> 01:10.950 So this is the date in which file was last updated or last modified. 01:10.980 --> 01:15.090 You have a content type, you have the content length. 01:15.120 --> 01:18.750 Content length is very important when you are sending a partial get request. 01:18.750 --> 01:23.100 I hope you remember and you have a cache control which is public. 01:23.100 --> 01:31.530 So these specific headers sometimes becomes quite important and there can be a possibility where client 01:31.530 --> 01:36.270 just needs to know the header field and not the message body. 01:36.660 --> 01:43.020 So if a client just wants to know the header field, then the head method is something which will be 01:43.020 --> 01:43.890 useful. 01:44.340 --> 01:51.740 So head method is used to fetch only the Http headers as part of the response. 01:51.750 --> 01:59.400 Now, whenever a head method is used, so a head method is very identical to a get method, except that 01:59.400 --> 02:04.410 the server must not return a message body in the response. 02:04.410 --> 02:05.670 This is very important. 02:05.700 --> 02:15.660 Whenever a head based header is sent to the web server, the web server should send the response but 02:15.660 --> 02:17.610 without the message body. 02:18.180 --> 02:22.950 Now the example is very simple You have a curl hyphen. 02:22.950 --> 02:30.630 I followed by the URL of the server for which you are sending a head based request. 02:31.170 --> 02:31.770 Perfect. 02:31.770 --> 02:33.600 So let's do one thing. 02:33.600 --> 02:40.520 Let's go ahead and I'll start Wireshark as well so that it will become much more simpler for us to see 02:40.530 --> 02:42.090 on what exactly is happening. 02:43.560 --> 02:44.460 I'll start. 02:44.460 --> 02:47.850 And this time let me do a curl. 02:50.760 --> 02:56.730 I say Dexter dot k p labs dot n say sample dot HTML. 02:58.860 --> 03:02.950 And now you will see it returned only the header fields. 03:02.970 --> 03:04.860 So I'll stop the wireshark 03:07.050 --> 03:13.140 and let's put http so that it will become much more simpler. 03:14.160 --> 03:16.080 So this is the Http. 03:19.520 --> 03:21.810 Packet corresponding to a keyword request. 03:21.810 --> 03:29.550 So if I do a http stream now, what you will see is what curl did. 03:29.570 --> 03:30.020 Curl. 03:30.020 --> 03:35.800 Instead of sending get it, send a head for slash sample dot HTML. 03:35.810 --> 03:44.210 So now in response to this, what a web server did, web server sent only the response header. 03:44.210 --> 03:46.700 It did not send the message body. 03:46.880 --> 03:56.150 However, if you remove the hyphen I over here you will find that it now sent the response body as well. 03:56.150 --> 04:02.480 And this is the basics about the Http head method. 04:02.510 --> 04:09.230 Again, this becomes very very important because you need to know on what are the parameters which your 04:09.980 --> 04:13.720 web server is accepting for a specific resource. 04:13.730 --> 04:19.880 This also helps a lot in cache control as well as partial gets as well. 04:19.880 --> 04:26.060 So we'll be looking into this once we go ahead and work with a web server. 04:26.070 --> 04:28.340 Nginx in great detail. 04:28.340 --> 04:30.290 So this is it about this lecture. 04:30.290 --> 04:37.100 I hope the basic Http head header is understood and if you have any doubts, questions, suggestions, 04:37.100 --> 04:43.540 feel free to connect us at Twitter, Facebook or LinkedIn or mail us at instructors at their labs dot 04:43.550 --> 04:43.680 in. 04:43.730 --> 04:44.960 Thanks for watching.