WEBVTT 00:00.170 --> 00:03.950 Hey, everyone, and welcome back to the Knowledge Portal Video series. 00:03.980 --> 00:09.560 Now, in the earlier lecture, we were discussing the basic about what protocols are all about. 00:09.590 --> 00:14.740 Now, continuing our journey today, we'll be discussing the basics of Http protocol. 00:14.750 --> 00:19.070 So let's go ahead and understand more about it with a simple use cases. 00:21.330 --> 00:23.850 So on the left hand side, you have a client. 00:23.850 --> 00:28.440 Let's assume this as a web browser, a Google Chrome or a Mozilla Firefox. 00:28.440 --> 00:31.230 And on the right hand side you have a web server. 00:31.470 --> 00:35.880 So this web server has certain files within it. 00:35.910 --> 00:38.460 Now, there are three files that you will see over here. 00:38.490 --> 00:45.120 One is movies dot HTML, second is documentary dot mp4, and third is my song dot mp3. 00:45.450 --> 00:52.310 Now this client wants to play documentary dot mp4, which is there within the web server. 00:52.320 --> 01:00.840 So in a very simple terms, how this would really work is the client or a web browser will send a request 01:00.840 --> 01:05.910 to the server asking that I want to watch documentary dot mp4. 01:06.330 --> 01:13.380 Now, depending upon the settings configured in the web server, the web server will reply back saying 01:13.380 --> 01:21.340 that here you go and it will send the documentary dot mp4 file back to the client's web browser. 01:21.640 --> 01:28.870 Now, depending on what kind of player like VLC or HTML5 player, what kind of player a browser has, 01:28.870 --> 01:35.440 it will go ahead and play this documentary MP4, which the server has sent back. 01:35.800 --> 01:41.620 So this is a very simple way of communication between a client and a server. 01:41.850 --> 01:44.530 Http protocol is very similar. 01:44.530 --> 01:47.890 So let's take an example of Http protocol now. 01:48.190 --> 01:55.450 So a web browser will send a request to the web server this time instead of the plain English language 01:55.450 --> 01:56.770 which we had used. 01:56.830 --> 02:00.010 They will be using the Http language. 02:00.310 --> 02:02.700 So what web browser will do? 02:02.710 --> 02:09.700 Web browser will send a request which would be get followed by the name of the file, which is get documentary 02:09.730 --> 02:10.870 dot mp4. 02:10.900 --> 02:15.730 Get basically means that I want to fetch this specific file. 02:16.210 --> 02:25.030 So web server will understand that the client wants to fetch the documentary dot mp4 so the web server 02:25.030 --> 02:32.830 will fetch the documentary MP4 and it will send it back to the client. 02:33.370 --> 02:37.000 Now in the response you see, you have 200. 02:37.000 --> 02:37.510 Okay. 02:37.540 --> 02:38.440 200. 02:38.440 --> 02:38.770 Okay. 02:38.770 --> 02:42.520 Means your request has been successfully processed. 02:42.520 --> 02:46.480 And this is the documentary dot mp4. 02:46.630 --> 02:53.260 Along with that, the web server will also have a header called as content type, which basically tells 02:53.260 --> 03:01.540 what type of content it is, which basically signifies that this specific file is a type video and sub 03:01.540 --> 03:02.680 type is mp4. 03:02.710 --> 03:10.270 So now the web browser will understand that the file which the web server has sent it is of type video 03:10.270 --> 03:16.990 and MP4, and then it will play this specific file according to the player that it has. 03:17.140 --> 03:25.600 So very simple way of communication between a web server and a client. 03:25.600 --> 03:27.040 So let's do one thing. 03:27.040 --> 03:32.230 Let's fire up our Wireshark so this things become much more clear to us. 03:33.760 --> 03:36.010 So let's do one thing. 03:36.010 --> 03:39.880 I have my wireshark up and running, so there are three interfaces over here. 03:39.880 --> 03:43.600 I'm using Wi-Fi, so I'll be selecting the Wi-Fi interface. 03:44.020 --> 03:47.020 So I'll start the capture. 03:47.020 --> 03:52.660 And now let me go ahead and type Dexter Labs dot in. 03:54.490 --> 04:03.700 So this is a very simple page where you have a text information call as let's say, Http and you have 04:03.700 --> 04:06.730 a simple labs dot logo which are designed. 04:07.900 --> 04:12.790 So when you go to the Wireshark now I'll stop the packet capture. 04:17.790 --> 04:20.010 Let's go down. 04:22.340 --> 04:25.640 And this is the get request that was sent. 04:26.120 --> 04:27.670 Let's do one thing. 04:27.680 --> 04:33.530 I'll right click here and I'll select follow the TCP stream. 04:33.920 --> 04:35.240 So. 04:38.340 --> 04:40.050 Let's find it out. 04:40.050 --> 04:41.220 Follow TCP stream. 04:42.030 --> 04:42.970 Perfect. 04:42.990 --> 04:47.580 So now what has happened is this is all internal happenings. 04:47.580 --> 04:50.030 You will not see this in the browser. 04:50.040 --> 04:59.430 So what happened was browser sent this request when we typed Dexter Labs in browser, sent a get request 04:59.430 --> 05:01.830 on the host Dexter Labs. 05:04.580 --> 05:11.180 Now the Web server which is running here, which is running on Dexter's labs and receive the request 05:11.180 --> 05:14.480 and it responded back with 200. 05:14.480 --> 05:14.900 Okay. 05:15.080 --> 05:16.010 200. 05:16.010 --> 05:16.370 Okay. 05:16.370 --> 05:21.830 Basically means the request that my browser made is successfully processed. 05:22.040 --> 05:29.060 And along with that it sent HTML contents back, which you will see you have. 05:29.060 --> 05:34.430 Let's Http and you also have the labs hyphen logo dot PNG. 05:35.180 --> 05:38.370 So this is what actually happened behind the scenes. 05:38.390 --> 05:44.330 Now if you'll see over here, along with the get request, there are a lot of other Http headers which 05:44.330 --> 05:47.310 the browser has sent to the web server. 05:47.330 --> 05:54.110 Now all of these are very important for communication and depending upon the headers which the browser 05:54.110 --> 06:00.950 or a client sends to the web server, the web server will respond according to that. 06:01.640 --> 06:07.680 So this is a very simple way of communication. 06:07.680 --> 06:12.900 So this response that you see over here, you can actually see in the web browser. 06:12.900 --> 06:20.340 So if you right click over here and do a view page source, this is the exact contents that you will 06:20.340 --> 06:21.040 see over here. 06:21.060 --> 06:26.630 So this is the high level overview about the Http protocol. 06:26.640 --> 06:35.010 In the subsequent lectures we will be discussing about each and every headers, which are part of a 06:35.010 --> 06:42.600 routine Http communication so that it will give us a very solid foundation in the Http protocol. 06:43.170 --> 06:51.570 So if you might be wondering how these things are decided and the answer to this is the RFC of Http 06:51.570 --> 06:52.050 protocol. 06:52.050 --> 07:01.380 So RFC basically contains the rules of a Http protocol, and these rules are being followed both by 07:01.380 --> 07:03.780 the client as well as the web server. 07:03.780 --> 07:09.100 And since the rules are followed on both the ends, the communication can proceed. 07:09.120 --> 07:13.810 So we'll be discussing more about all of these in the subsequent lectures. 07:13.830 --> 07:20.790 I hope you understood the basic about the Http protocol in a high level overview and if you have any 07:20.790 --> 07:26.940 doubts, suggestions, questions, feel free to connect us at Twitter, Facebook or LinkedIn or mail 07:26.940 --> 07:29.370 us at instructors at the Rate Labs dot in. 07:29.460 --> 07:30.660 Thanks for watching.