1 00:00:01,200 --> 00:00:05,130 We've now got a pretty reasonable set up with Lerner inside of a project, so we're not going to turn 2 00:00:05,130 --> 00:00:08,810 our attention back over to actually implementing different portions of our app. 3 00:00:09,630 --> 00:00:14,850 The first portion that we're going to focus on is the so remember, our Seelie is going to be a program 4 00:00:15,120 --> 00:00:17,280 that we want a user to run from their terminal. 5 00:00:17,610 --> 00:00:22,350 So at some point in time, we're going to expect user to run a command like daybook server or something 6 00:00:22,350 --> 00:00:22,950 very similar. 7 00:00:23,340 --> 00:00:28,560 When a user runs this command, we're going to run the code inside of our CLIA package. 8 00:00:28,950 --> 00:00:32,549 And inside that package, we're going to have some amount of code that is going to start up our local 9 00:00:32,549 --> 00:00:33,330 API. 10 00:00:34,230 --> 00:00:39,870 Now, you might recall that whenever we run JDBC Reserve, we might also want to allow a couple of optional 11 00:00:39,870 --> 00:00:41,950 arguments to be passed along with his command as well. 12 00:00:42,510 --> 00:00:47,880 So, for example, remember, we have said that whenever a user starts to change some cells inside the 13 00:00:47,880 --> 00:00:52,950 browser, we want to somehow take that information, take that text, take that code and persistent 14 00:00:52,950 --> 00:00:54,590 to a file on the user's hard drive. 15 00:00:54,900 --> 00:00:59,610 And we have said specifically that we want to save it into a file so the user can very easily share 16 00:00:59,610 --> 00:01:02,700 that file with other people or committed to get or whatever else. 17 00:01:03,540 --> 00:01:08,820 So as a part of our Seelie, we might want to allow a user to specify exactly what file they want to 18 00:01:08,820 --> 00:01:12,740 open up to get a list of cells from or to save cells into. 19 00:01:13,440 --> 00:01:18,660 So we might want to allow a little variance on this command, maybe something like JDBC serve and then 20 00:01:18,660 --> 00:01:21,390 some file name like say, maybe notebook. 21 00:01:22,830 --> 00:01:27,870 So if a user ran this command, that would mean that we would want to open up the notebook as file inside 22 00:01:27,870 --> 00:01:31,230 the current directory, see if there is already a list of cells saved in there. 23 00:01:31,500 --> 00:01:36,900 And then otherwise, if a user ever changes any code or text inside the browser, we're going to save 24 00:01:36,900 --> 00:01:39,810 the list of cells back into this notebook as file. 25 00:01:40,440 --> 00:01:43,490 And remember, there's nothing special about the name notebook's. 26 00:01:43,860 --> 00:01:47,150 This can be any JavaScript file name that we can possibly imagine. 27 00:01:47,160 --> 00:01:51,060 So it can be notebook or book or my notes or whatever else. 28 00:01:53,050 --> 00:01:58,330 In addition, there's another variant to the book of command that we might want to enable whenever we 29 00:01:58,330 --> 00:01:59,150 run this command. 30 00:01:59,170 --> 00:02:03,580 We're going to start up that local API, which is going to be the server that is going to actually save 31 00:02:03,580 --> 00:02:10,479 information into this my notes file or whatever we end up calling it, that local API has to be running 32 00:02:10,479 --> 00:02:13,840 or listening for traffic on a very specific port on the user's machine. 33 00:02:14,200 --> 00:02:16,900 And maybe we want to allow a user to customize that port. 34 00:02:17,320 --> 00:02:23,910 So maybe another variant of this book server command would be something like my notes, James Dash Dash 35 00:02:23,920 --> 00:02:28,000 Port and then the port that the user wants to run the local API on. 36 00:02:28,090 --> 00:02:34,210 So in this case, we would start up the local API on 30 50 instead of whatever default we decide to 37 00:02:34,210 --> 00:02:34,600 use. 38 00:02:35,670 --> 00:02:40,380 So at this point time, I'm trying to kind of communicate here is to say there are several different 39 00:02:40,380 --> 00:02:44,250 variants of the books of command that we eventually want to implement. 40 00:02:44,620 --> 00:02:50,760 We want to allow Gebo excerpt to be ran by itself with a file name, with a file name and a port, and 41 00:02:50,760 --> 00:02:52,860 maybe also with just a port by itself. 42 00:02:53,200 --> 00:03:00,060 So something like daybook serve Port 30 50 so that we've got many different variants of this command. 43 00:03:00,720 --> 00:03:05,520 So whenever we start to run our Seelie, we need to figure out how to read in these different command 44 00:03:05,520 --> 00:03:08,970 line arguments and then customize our program in a very specific way. 45 00:03:10,100 --> 00:03:13,940 So to understand how to read in command line arguments, this might be something you are already familiar 46 00:03:13,940 --> 00:03:16,490 with, but let me just give you a very, very quick reminder. 47 00:03:16,850 --> 00:03:23,080 We're going to do a very quick little test here back inside of my coat, Ed. I'm going to find my route 48 00:03:23,090 --> 00:03:24,110 project directory. 49 00:03:24,110 --> 00:03:27,300 And inside there, I'm going to make a new file called Test. 50 00:03:29,490 --> 00:03:39,180 Inside this file, I'm going to add in one line of code UNCLOG process, dot RGV process is an array 51 00:03:39,180 --> 00:03:39,870 of strings. 52 00:03:40,170 --> 00:03:45,120 Inside of that array is a list of all the different options that are provided to our program whenever 53 00:03:45,120 --> 00:03:46,250 we run this test. 54 00:03:46,290 --> 00:03:51,600 JS file process is automatically provided to us by node itself. 55 00:03:52,430 --> 00:03:57,110 Let's save this file very quickly and then going to go back over to my terminal and try to run this 56 00:03:57,110 --> 00:03:59,000 file with a couple of come in line arguments. 57 00:04:01,090 --> 00:04:10,510 OK, so there's the test case file, I'll do a node asks and I'm going to add in my notes and dash dash 58 00:04:10,510 --> 00:04:12,730 port 30 50 like so. 59 00:04:14,460 --> 00:04:21,510 Now, when I run this, I'll see the contents of that process array, the first line right here is the 60 00:04:21,510 --> 00:04:23,760 path to the node executable on your machine. 61 00:04:24,370 --> 00:04:30,630 The second element, I should say, the first element, the element at index one is the path to the 62 00:04:30,630 --> 00:04:31,710 file that we executed. 63 00:04:32,400 --> 00:04:35,930 And then we were given a list of all the other command line arguments that are provided to us. 64 00:04:36,540 --> 00:04:41,310 So you and I could try to write out a little bit of code that takes a look at these different elements 65 00:04:41,310 --> 00:04:45,180 right here and then use these different elements to customize how our program works. 66 00:04:45,630 --> 00:04:50,930 So if we have some file mentioned right here, clearly that would mean that we want to open up the my 67 00:04:50,940 --> 00:04:54,600 notes, not just file and find a list of cells in there or something like that. 68 00:04:55,080 --> 00:04:59,790 And then if we see the dash dash port, we could try to find the number right after it and make sure 69 00:04:59,790 --> 00:05:01,750 that our API listens on that port. 70 00:05:02,550 --> 00:05:07,440 Now, we could definitely try to write out all this logic ourselves to look at this process, the array. 71 00:05:07,680 --> 00:05:10,230 But we would very quickly get into a little bit of trouble. 72 00:05:10,740 --> 00:05:16,350 Remember that in general, there are several different kind of assumed variations of many different 73 00:05:16,350 --> 00:05:19,590 commands that a lot of different engineers are going to assume just work. 74 00:05:19,950 --> 00:05:28,830 So, for example, many engineers would assume that Dashty support space 30 50 is equivalent to 40 equals 75 00:05:29,010 --> 00:05:29,760 30 50. 76 00:05:30,620 --> 00:05:35,110 But if I run that, that dramatically changes the process, aragvi array. 77 00:05:35,680 --> 00:05:40,370 So if we were going to manually process this array right here, we would have to kind of accommodate 78 00:05:40,370 --> 00:05:44,590 or write out some logic to accommodate for the two different variations of providing aiport option. 79 00:05:45,320 --> 00:05:50,300 In addition, many engineers generally assume that you might be able to provide different options in 80 00:05:50,300 --> 00:05:52,460 any order when you are running a command. 81 00:05:52,850 --> 00:05:57,920 So, for example, another engineer might assume that they could put in a dash dash port right there 82 00:05:58,370 --> 00:06:01,520 of 30 50 and then the name of the file they want to open. 83 00:06:02,710 --> 00:06:09,460 Well, if we run that once again, the order of the process RGV array has changed and again, we probably 84 00:06:09,460 --> 00:06:13,840 don't want to have to write out really exhaustive logic to figure out all these different variations 85 00:06:13,840 --> 00:06:20,650 of order rather than trying to write out our own custom man line implementation and try to read in all 86 00:06:20,650 --> 00:06:23,740 the different variations of mainline arguments. 87 00:06:23,770 --> 00:06:26,170 We're going to instead use a library to do it for us. 88 00:06:26,900 --> 00:06:31,210 The library we are going to use is called Commander and we actually already installed that into our 89 00:06:31,210 --> 00:06:33,850 Seelie project a little bit ago using llena. 90 00:06:35,510 --> 00:06:40,150 So let's go take a look at some documentation around, Commander, very quickly, back inside my browser, 91 00:06:40,580 --> 00:06:44,750 I'm going to go to NPM Jase's Dotcom and search for commander. 92 00:06:49,120 --> 00:06:54,220 This is a library that is all about helping you build out command line interfaces, so pretty much doing 93 00:06:54,220 --> 00:06:57,020 exactly what we just described, reading in different commands. 94 00:06:57,040 --> 00:07:00,010 We're trying to run and then reading in different options we might provide. 95 00:07:00,520 --> 00:07:03,340 If you want to, you can take a quick look at the documentation here. 96 00:07:03,370 --> 00:07:08,020 But I'm going to be honest with you, there is a tremendous amount of documentation and it's rather 97 00:07:08,020 --> 00:07:10,390 challenging to read through all of it in one go. 98 00:07:10,840 --> 00:07:15,370 So this is one of those scenarios inside this course where we're going to come back the next video and 99 00:07:15,370 --> 00:07:18,300 we're pretty much just going to say, hey, here's how you make use of commander. 100 00:07:18,340 --> 00:07:20,410 So we're not really going to focus too much on the documentation. 101 00:07:20,440 --> 00:07:24,130 I'm just going to give you a very direct explanation of do exactly this. 102 00:07:24,130 --> 00:07:27,670 Here's a good pattern to follow, and we're pretty much going to run with that. 103 00:07:28,600 --> 00:07:33,640 OK, so the last thing I want to do is just very quickly go back over to my editor and delete that test 104 00:07:34,240 --> 00:07:34,570 file. 105 00:07:36,200 --> 00:07:37,580 All right, so let's take a pause right here. 106 00:07:37,580 --> 00:07:41,690 When we come back in just a moment, we'll start writing out some code inside of our Seelie package.