WEBVTT 00:00.660 --> 00:08.190 In the last module we have already seen on why the Http expires and the Http date headers are useful 00:08.190 --> 00:10.740 as far as the http caching is concerned. 00:12.380 --> 00:20.120 So in this module we'll configure our Nginx machine to include the expires header for different file 00:20.120 --> 00:20.900 formats. 00:22.330 --> 00:27.460 So for our scenario, we have two file formats that we'll be using. 00:27.460 --> 00:30.560 One is dot txt and one is dot PNG. 00:30.580 --> 00:34.390 So essentially they are the text and image file format. 00:34.630 --> 00:39.190 And for each file format we will set a different expiry header. 00:40.280 --> 00:42.290 So let's see on how we can do that. 00:43.770 --> 00:50.040 So let me do a call on example.com slash logo dot PNG. 00:51.890 --> 00:53.150 Ah, so sorry. 00:54.260 --> 00:54.660 Pinch it. 00:55.430 --> 00:58.910 So if we see over here, the date header is included. 00:58.940 --> 01:04.490 However, there is no expires header for this particular file. 01:05.570 --> 01:08.870 Same goes for the sample dot txt. 01:11.860 --> 01:15.220 The date header is mentioned, but there is no expires header. 01:15.490 --> 01:20.440 So let's see on how we can configure the expires header for both of them. 01:22.350 --> 01:25.590 So I'll go to ATC Nginx. 01:27.670 --> 01:31.480 Conniff And let's open Conniff. 01:33.340 --> 01:35.650 Now, this is a simple configuration file. 01:36.340 --> 01:45.880 So let's add one more location directive that will basically specify for any image file on the website. 01:46.630 --> 01:50.470 Gash that image for, let's assume, 48 hours. 01:51.550 --> 01:53.230 So browser. 01:53.230 --> 01:59.710 When it opens image from example.com, it will cache it for 48 hours. 01:59.920 --> 02:00.820 So. 02:03.270 --> 02:04.860 Include location director. 02:06.090 --> 02:08.790 Say for any image. 02:10.590 --> 02:11.670 Say I'll say. 02:11.700 --> 02:12.480 PNG file. 02:13.080 --> 02:14.970 You can even include Jpeg. 02:16.780 --> 02:18.220 I'll say expires. 02:19.240 --> 02:20.110 48 hours. 02:21.830 --> 02:23.480 You also have to mention the. 02:26.620 --> 02:29.020 Root location for the images, which is. 02:29.440 --> 02:31.060 I'll just copy it from the here. 02:33.820 --> 02:34.120 Okay. 02:45.280 --> 02:45.850 Okay. 02:45.850 --> 02:56.800 So the expires directive basically tells that any file that ends with PNG extension, which is from 02:56.800 --> 03:02.830 this particular directory, the expires of that file should be 48 hours. 03:02.830 --> 03:10.450 So basically what nginx will do is Nginx will add a expires header which will expire after 48 hours 03:10.450 --> 03:12.310 of the time of response. 03:12.580 --> 03:16.690 So i'll save this particular and let's do next. 03:17.020 --> 03:17.530 Okay. 03:17.530 --> 03:18.970 Let's reload nginx. 03:21.180 --> 03:21.410 Awesome. 03:23.320 --> 03:26.740 So now if we do a call on Http. 03:28.190 --> 03:30.680 Example.com logo dot PNG. 03:32.570 --> 03:33.440 Then. 03:34.250 --> 03:37.400 Now you see an expired header has been introduced. 03:39.540 --> 03:42.150 Now, we have already mentioned 48 hours. 03:42.150 --> 03:45.930 So if we look into the date header, date header is. 03:47.180 --> 03:55.660 18th November, Wednesday at 110 and expires is 20th November at 110. 03:55.670 --> 04:01.040 So this is exactly 48 hours from the time the response has come. 04:02.030 --> 04:06.710 Now, if you also notice Enginex has also introduced the cache control header. 04:06.740 --> 04:10.280 Max hyphen h followed by the second. 04:11.540 --> 04:17.170 So this basically if you multiply, then it becomes 48 hours. 04:17.180 --> 04:25.490 So this second corresponds to the number of hours after which the image or the cache should be considered 04:25.490 --> 04:25.940 stale. 04:27.690 --> 04:35.910 Now we have already discussed expires header is specifically for the Http 1.0 protocol in the 1.1, 04:35.940 --> 04:45.750 the nginx or the Http has introduced a new header field which is cache control where the expiry is mentioned 04:45.750 --> 04:47.130 in seconds. 04:47.940 --> 04:49.320 So for. 04:51.000 --> 04:58.080 All the Http 1.1 client, they'll actually read the cache control directive and not the expires header 04:58.080 --> 04:58.960 field over here. 05:00.570 --> 05:07.260 So even if you don't mention explicitly the cache control nginx will automatically add when you add 05:07.260 --> 05:11.790 the expires field within the location directive that we have already added. 05:12.980 --> 05:16.280 Now, this is specifically for the image file. 05:16.280 --> 05:22.730 So if we go on sample dot text, still it is not showing any expires header. 05:22.730 --> 05:24.170 So we have to. 05:25.480 --> 05:27.820 Specify for the text file as well. 05:27.910 --> 05:40.720 So if I will have to add one more location directive, say anything which ends with dot txt route would 05:40.720 --> 05:41.440 be the same. 05:47.080 --> 05:48.550 I'll say expires. 05:48.580 --> 05:49.420 I'll say one hour. 05:52.100 --> 05:55.270 I'll save the file and I'll reload the enginex. 05:57.580 --> 06:02.770 Let's clear the screen and let's do a call again on example.com. 06:04.590 --> 06:05.970 Slash sample.txt. 06:09.840 --> 06:19.710 And now you see the expires header has been added and for ease of readability it is 3600 seconds, which 06:19.710 --> 06:20.760 counts to one hour. 06:20.910 --> 06:31.620 So it will tell the cache that this response can be considered as the latest response for one hour. 06:33.540 --> 06:42.850 Now going back to the web conf, you can actually specify the negative value as well. 06:42.870 --> 06:46.740 So if I say minus one over here and let's do reload 06:49.230 --> 06:50.880 and if we go. 06:54.980 --> 06:57.800 You see basically the. 06:58.940 --> 07:06.560 Okay, date was 140 and the expires is also 114. 07:06.560 --> 07:12.890 So basically this means that do not cache this particular response. 07:12.890 --> 07:15.440 So sample.txt should not be cached. 07:15.470 --> 07:21.080 So even if you see in the cache control, there is a new field which is no cache which has been introduced. 07:21.680 --> 07:30.710 So if you want to include or if you want to instruct the browsers to not cache this particular responses, 07:30.710 --> 07:35.900 then you can actually say expires minus one and this will do the job. 07:37.310 --> 07:45.080 So this is it about how you can include the expires header as far as the responses are concerned? 07:45.410 --> 07:47.530 So this is it about this module. 07:47.540 --> 07:51.350 I hope this has been informative for you and I'd like to thank you for viewing.