1 00:00:00,720 --> 00:00:02,830 I will come back in this lecture. 2 00:00:02,850 --> 00:00:11,040 I'll show you how to do a simple request that goes out onto the Web, grabs the content of a text file 3 00:00:11,040 --> 00:00:18,030 stored in a publicly accessible Eurorail, and then presents the contents of this text file onto the 4 00:00:18,030 --> 00:00:18,350 show. 5 00:00:19,140 --> 00:00:26,170 So here's the example sketch that I've prepared to demonstrate how to do a simple request. 6 00:00:26,880 --> 00:00:34,290 This script uses the network requests and Jason modules, which I described in the previous lecture. 7 00:00:34,620 --> 00:00:41,460 On top of them, I'm also using the USIS module, which allows me to do something like this down here. 8 00:00:41,460 --> 00:00:49,500 And basically, if my ISP 32 fails to connect to my local Wi-Fi network, it will just call the exit 9 00:00:49,680 --> 00:00:58,020 method that belongs to the user's module and stop the execution of the program and then I'll get back 10 00:00:58,020 --> 00:00:58,750 to the show. 11 00:00:59,640 --> 00:01:03,000 So that's the only thing that I've added to this script. 12 00:01:03,000 --> 00:01:09,930 In addition to the modules that are described in the previous lecture before we have a look at the actual 13 00:01:09,930 --> 00:01:16,680 code, I just want to show you that I have created a simple text file, this text file here, which 14 00:01:16,680 --> 00:01:18,390 is available on my website. 15 00:01:18,920 --> 00:01:25,200 Its name is Hemorrhoidal takes the and just a couple of lines of text here that I'm going to fetch. 16 00:01:26,190 --> 00:01:30,480 I have stored this file on my Web server. 17 00:01:30,480 --> 00:01:37,860 As I said, this is its name and I'm able to use them to make modifications. 18 00:01:38,460 --> 00:01:40,530 So this is my interface. 19 00:01:40,530 --> 00:01:47,280 I'm going to make a change to this in a moment and see how that change affects what the script presents 20 00:01:47,280 --> 00:01:48,120 on the shell. 21 00:01:48,420 --> 00:01:55,440 In your case, if you don't have a Web server, you can just place this file on any publicly accessible 22 00:01:56,310 --> 00:01:57,000 location. 23 00:01:57,000 --> 00:02:04,050 Jerrell, it could be could be perhaps even a Dropbox Eurorail or a Google drive. 24 00:02:04,050 --> 00:02:12,720 Your real just tried to make the target file as small as possible because it's got too many characters 25 00:02:12,720 --> 00:02:13,230 in it. 26 00:02:13,230 --> 00:02:19,140 It will most likely exceed the memory of arem limitations of your HP thirty two. 27 00:02:19,140 --> 00:02:21,710 And that will cause the script to crash. 28 00:02:22,050 --> 00:02:26,610 So just remember that you're easiest to do, has a limited amount of ram and therefore you won't be 29 00:02:26,610 --> 00:02:37,650 able to fetch large files from the web that will exceed that limited memory space in its frame. 30 00:02:38,080 --> 00:02:42,480 Again, that will cause the E.S.P to in your script to crash. 31 00:02:43,110 --> 00:02:43,470 All right. 32 00:02:43,470 --> 00:02:45,030 So I've got my recommendation here. 33 00:02:45,030 --> 00:02:48,210 You can check it out for more details and. 34 00:02:49,700 --> 00:02:57,000 Let's have a look at what is going on now, so in line 40 to the first thing to do is to use the with 35 00:02:57,050 --> 00:02:58,630 open structure. 36 00:03:00,630 --> 00:03:06,040 To open up this Jason file, which is this Jason file right here. 37 00:03:06,070 --> 00:03:12,840 So if you never work with Jason file before, then be assured there's nothing difficult about them. 38 00:03:13,830 --> 00:03:21,560 They all start with curly brackets, top and bottom, and then you can have your value pairs in this 39 00:03:21,570 --> 00:03:22,250 notations. 40 00:03:22,260 --> 00:03:26,100 They've got in quotes the name of the value. 41 00:03:26,370 --> 00:03:32,100 And then you've got if you talk about a string, you've got, again, double quotes with the value. 42 00:03:33,150 --> 00:03:34,910 You could have a number here as well. 43 00:03:34,920 --> 00:03:42,990 If you want to store a numerical value or could be an integer or a number that contains decimals. 44 00:03:43,650 --> 00:03:50,430 And then you just need to remember to put a comma there and then you have the next value pair and so 45 00:03:50,430 --> 00:03:50,730 on. 46 00:03:50,860 --> 00:03:59,340 So be using this chasten file to contain the credentials of my wi fi network to which my microcontroller 47 00:03:59,340 --> 00:04:03,630 is connecting to or perhaps an epic for a remote resource. 48 00:04:04,170 --> 00:04:11,520 And you need to store this file through the files here for my especially too. 49 00:04:11,730 --> 00:04:12,350 Right. 50 00:04:12,360 --> 00:04:21,030 So you need to make sure that this Jason file to make the bottom pane a bit bigger. 51 00:04:21,070 --> 00:04:21,830 You can see. 52 00:04:21,840 --> 00:04:22,390 There you go. 53 00:04:22,950 --> 00:04:23,310 All right. 54 00:04:23,320 --> 00:04:29,930 So you need to make sure that this file is stored in the file system of your macropod device or the 55 00:04:30,120 --> 00:04:31,220 facility in this case. 56 00:04:31,620 --> 00:04:39,930 So I'm just going to upload it over and make sure it is right here so that my script will be able to 57 00:04:39,930 --> 00:04:40,290 read. 58 00:04:40,290 --> 00:04:49,200 It can sit forward slash, which means that it's in the root of the storage python device and then it 59 00:04:49,200 --> 00:04:49,840 will open it up. 60 00:04:50,580 --> 00:04:57,440 So once the file is opened, I've got a variable or an object that is the handle to this file. 61 00:04:57,870 --> 00:05:06,420 So call it credentials and this code, Jason, and then I can use this command here, credentials and 62 00:05:06,420 --> 00:05:11,310 this code, Jason, or whatever name you've given to your file, don't read. 63 00:05:11,550 --> 00:05:15,330 And they're just going to bring in the whole file, the entire file. 64 00:05:15,960 --> 00:05:23,100 Then you're going to use Jason Load's, which is going to take this text file and convert it into a 65 00:05:23,640 --> 00:05:29,700 Jason object, in which case that is called settings and inside settings. 66 00:05:29,700 --> 00:05:38,250 I'll be able to use commands such as this settings and then in square brackets, the name of the value 67 00:05:38,250 --> 00:05:40,380 pair that I want to extract like this. 68 00:05:40,740 --> 00:05:48,240 And that will give me in this case, the value, which is the name of my Wi-Fi network, and I'm doing 69 00:05:48,240 --> 00:05:50,460 the same thing for the password. 70 00:05:50,970 --> 00:05:59,190 Therefore, he can use this construct to store any sensitive information such as login credentials outside 71 00:05:59,490 --> 00:06:07,410 of the main micro python script and will be using this method in the next few lectures as well. 72 00:06:08,430 --> 00:06:11,780 Next, I've got a variable to hold the URL. 73 00:06:12,330 --> 00:06:21,150 This is a girl that points to the simple text file a text and I've got a method here called Do Connect. 74 00:06:21,290 --> 00:06:23,730 Can probably guess what it's meant to do. 75 00:06:25,860 --> 00:06:30,540 This method is called down here, so let's jump down here first. 76 00:06:30,740 --> 00:06:42,240 I create a W land object and I'm passing the network dot SDK if underscore, if constant, which means 77 00:06:42,240 --> 00:06:46,410 that what I'm trying to do is to connect to a wi fi hotspot. 78 00:06:47,370 --> 00:06:55,140 So I'll get my object for the wireless lan, then I'll call do connect program jumps up here, a 10 79 00:06:55,140 --> 00:06:56,340 on the interface. 80 00:06:56,730 --> 00:07:01,110 And if I'm not already connected, which this is the first time that I will go through this, I won't 81 00:07:01,110 --> 00:07:08,820 be connected then in a message to the shills that I know what's going on and then try to connect to 82 00:07:08,820 --> 00:07:15,170 those that don't connect method and passing the credentials as I'm grabbing them from the adjacent file 83 00:07:15,700 --> 00:07:18,540 is a name, the Wi-Fi name and the password. 84 00:07:19,020 --> 00:07:26,850 And then if I fail to connect, then I'm just going to print out this message and exit the program by 85 00:07:26,850 --> 00:07:31,420 calling exit and passing a zero ID here. 86 00:07:32,330 --> 00:07:36,450 It doesn't make any difference whether you pass anything or not here in MacRobertson. 87 00:07:38,870 --> 00:07:47,780 Otherwise, we continue in line 62, and so long as we do have a connection and still have a connection, 88 00:07:47,780 --> 00:07:56,270 hasn't dropped out for some reason are a couple of messages out, including the IP address that the 89 00:07:56,300 --> 00:08:09,230 Wi-Fi network has given to my ISP three to this if config method returns all of the network attributes 90 00:08:09,230 --> 00:08:11,660 that have been given to the ISP 32. 91 00:08:11,960 --> 00:08:20,510 And when I pass a zero index in this array, when I get back is the acquired IP address, I'm also printing 92 00:08:20,510 --> 00:08:23,880 the full array of information Isatabu up here as well. 93 00:08:23,900 --> 00:08:30,920 So you'll see that when I run the program for the first time, you'll see that the config method prints 94 00:08:30,920 --> 00:08:39,530 out the acquired IP address, the Gateway IP address, DNS, IP address and information such as that. 95 00:08:40,650 --> 00:08:49,800 Then going into line 65, where I use the get method, because I want to do a get request of the requests 96 00:08:49,800 --> 00:08:53,270 module and pass on the rail that I've set up up here. 97 00:08:54,240 --> 00:08:59,840 So that would actually do the get request to this where you are real. 98 00:09:00,630 --> 00:09:07,260 Then a few messages coming back, including line sixty eight, the response that I'm getting from the 99 00:09:07,260 --> 00:09:07,920 Web server. 100 00:09:07,930 --> 00:09:10,110 So this hopefully will give us. 101 00:09:11,200 --> 00:09:14,440 This text, this is two lines with a bit of text in it. 102 00:09:15,070 --> 00:09:16,640 All right, so as you can see, it's fairly simple. 103 00:09:16,660 --> 00:09:25,910 Let's try it out of looking at the version of the script that is stored on my local machine. 104 00:09:25,930 --> 00:09:28,930 I haven't uploaded yet to my HP with the. 105 00:09:29,190 --> 00:09:30,040 But that is OK. 106 00:09:30,040 --> 00:09:38,450 As long as the credentials file is here so that my script can get it, I can just click on the current 107 00:09:38,530 --> 00:09:42,580 script button and that will execute this script on the device. 108 00:09:43,120 --> 00:09:48,370 This is Connected Network can connect the network with giving credentials, history, making sure that 109 00:09:48,370 --> 00:09:49,420 this is correct. 110 00:09:51,260 --> 00:09:54,230 Right, I'm going to get rid of that tab. 111 00:09:54,790 --> 00:09:57,720 This is on the device, it looks OK. 112 00:09:58,490 --> 00:09:59,530 Let's try one more time. 113 00:10:01,240 --> 00:10:04,330 The second time it worked. 114 00:10:04,990 --> 00:10:11,050 All right, give so much space down here, so let's see what we have. 115 00:10:11,050 --> 00:10:13,300 First of all, we've got the netbook config. 116 00:10:13,360 --> 00:10:16,810 This is a it is printed from. 117 00:10:18,360 --> 00:10:19,710 This line right here. 118 00:10:21,150 --> 00:10:24,960 And you can see that this is the acquired IP address. 119 00:10:26,150 --> 00:10:26,990 The mosque. 120 00:10:28,120 --> 00:10:29,560 The gateway. 121 00:10:30,760 --> 00:10:33,220 And the DNS server. 122 00:10:35,710 --> 00:10:44,260 It's setting out contents from this location and this is the result, which is what I expected to make 123 00:10:44,260 --> 00:10:52,870 a little change to make that point, a few more numbers like that and then just save that right. 124 00:10:53,300 --> 00:10:56,850 If I refresh my vision document in my breath. 125 00:10:56,860 --> 00:11:02,650 So you see the additional numbers, let's do the same thing on with the script. 126 00:11:04,960 --> 00:11:05,480 All right. 127 00:11:05,500 --> 00:11:07,730 And you can see that it works. 128 00:11:07,750 --> 00:11:15,040 All right, so as you can see, this is a fairly simple way of getting data from a web resource. 129 00:11:15,070 --> 00:11:21,970 Now, imagine that this document, the FETCH data, was formatted, for example, as a comma delimited 130 00:11:21,970 --> 00:11:24,520 file or even an adjacent document. 131 00:11:24,790 --> 00:11:30,820 Then you'll be able to import the data from the document and decoded accordingly. 132 00:11:30,850 --> 00:11:39,040 So you could do a bit of text processing to extract data from your CSP file or use the Jason module 133 00:11:39,100 --> 00:11:42,950 to extract data from your adjacent file and so on. 134 00:11:44,140 --> 00:11:50,590 Anyway, I'm going to leave this example to this and move on to the next lecture where I'll show you 135 00:11:50,590 --> 00:11:56,830 how to send example a simulated sensor data to tweet DOD and.